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This chapter is devoted to focal disorders of the peripheral nervous system, including radiculopathies, plexopathies, and mononeuropathies. These conditions span a broad range of disorders, from radiculopathy due to Lyme disease and obturator neuropathy at the extremes of rarity to very common disorders such as cervical radiculopathy and carpal tunnel syndrome. This group of disorders makes up a large portion of neuromuscular medicine practice and only on a rare day will the neuromuscular clinician fail to see a patient with one of these conditions; on most days, this specialist is likely to see several. Intimate familiarity with the pathoanatomy, pathophysiology, clinical features, diagnosis, evaluation, and treatment of these conditions is necessary. This chapter is intended to provide a solid basis for acquiring the required expertise.
The intervertebral disk is the largest avascular structure in the body, depending for sustenance on the diffusion of nutrients across the endplate. The disks begin to desiccate and lose elasticity in the fifth and sixth decades; individuals in this age group are prone to intervertebral disk rupture. In the seventh to ninth decades, the tendency is to hardening and calcification, resulting in degenerative spondylosis and spinal stenosis.
Knowledge of the anatomic details of the spine and the spinal nerves is integral to managing patients with suspected radiculopathy. The vertebrae are separated by intervertebral disks, which are composed of an outer fibrous ring, the annulus fibrosus, and an inner gelatinous core, the nucleus pulposus (NP). The lateral recess is the corner formed by the pedicle, vertebral body, and superior articular facet. Hypertrophy of the facet can cause lateral recess stenosis.
The spinal nerve passes outward from the spinal canal through the intervertebral foramen, a passageway formed by the vertebral body anteriorly, pedicles above and below, and the facet mass and its articulation, the zygapophyseal joint, posteriorly. The zygapophyseal joints are innervated by the posterior primary ramus of the exiting spinal nerve and can be a source of pain. The uncovertebral joints (of Luschka), which are not true joints, are the points where the posterolateral surface of a cervical vertebra comes into apposition with a neighboring vertebra. Degenerative osteophytes projecting into the intervertebral foramen from the uncovertebral “joints” may narrow the foramen and cause radiculopathy ( Fig. 17.1 ).
The posterior longitudinal ligament (PLL) extends along the posterior aspect of the vertebral bodies and reinforces the disks posteriorly. The PLL is weak and flimsy and narrows as it descends. Disk herniations tend to occur posterolaterally, especially in the lumbosacral region, in part because of the lateral incompleteness of the PLL ( Fig. 17.2 ). In the cervical region, the PLL may ossify and contribute to spondylotic narrowing. The ligamentum flavum extends along the posterior aspect of the spinal canal. It buckles and folds during neck extension and may also contribute to canal narrowing.
The static anatomy of the spine provides only a partial understanding of the changes that occur on motion. Direct measurements have shown that the pressure within the lumbar disk varies markedly with different postures and activities. It is lowest when lying supine, increases 400% on standing, and increases a further 50% when leaning forward. The pressure is 40% higher when sitting than standing. The higher pressure when sitting is clinically relevant, as patients with lumbosacral disk ruptures characteristically have more pain sitting than standing. Eating meals from the mantelpiece is virtually pathognomonic. The intradiscal pressure during a sit-up is astronomical.
The size of the intervertebral foramina decreases with extension and with ipsilateral bending. In extension, the facet joints draw closer together and the posterior quadrants of the spinal canal narrow. The upper cervical spine is primarily responsible for rotational movements and the lower cervical spine for flexion and extension movements. The longitudinal and flavum ligaments alternately stretch and buckle during flexion and extension. Tethering by the dentate ligaments accentuates the mechanical stresses laterally. Cervical roots stretch with flexion and may angulate at the entrance to the foramen. The intraspinal subarachnoid pressure varies with respiration and increases markedly with Valsalva or restriction of venous outflow. Like veins everywhere, the epidural and radicular veins change in size with posture and respiration. All these dynamic changes, which are especially relevant in the presence of disease, form the basis for clinical tests and historical questions useful for distinguishing the various causes for neck pain.
The annulus provides circumferential reinforcement for the disk; the spherical NP allows the vertebral bodies above and below to glide and slip across it, like a ball bearing. The NP is eccentrically placed, closer to the posterior aspect of the disk. The relative thinness of the annulus posteriorly is another factor contributing to the tendency of disk herniations to occur in that direction.
The great majority of the weight-bearing function of a normal disk is borne by the NP, which contains proteoglycans, macromolecules that heartily imbibe fluid. Early in life, the NP is 90% water, but it undergoes progressive desiccation over time. With desiccation of the NP and loss of viscoelasticity and compressibility, the annulus must assume more of the weight burden. This increased load, in the face of its own degenerative weakening, then makes the annulus prone to tears. Intradiscal proteoglycans are innocuous, but, spilled into the epidural space in the course of disk rupture, they can incite an inflammatory response. Other inflammatory mediators and signaling substances may be released by disk rupture, including nitric oxide, prostaglandin E 2 , tumor necrosis factor, and interleukins-1 beta, -6, and -8.
The posterior aspects of the disks and the PLL are innervated by the sinuvertebral nerves, which arise from the anterior ramus just distal to the DRG, then take a recurrent course and reenter the spinal canal carrying both somatosensory and sympathetic fibers. These nerves have been implicated in discogenic pain ( ). An ingrowth of blood vessels and nerve fibers into the fibers of the annulus fibrosus of degenerated disks has been observed and may play a role in the development of back pain ( ). Both peripheral sensitization and central sensitization are likely involved in pain perpetuation.
The spinal roots exit more or less horizontally in the cervical spine, although there is a slight downward slant. The downward slant increases through the thoracic region. When the cord terminates at the level of L1–2, the remaining roots drop vertically downward in the cauda equina to their exit foramina (see Fig. 17.2 ). In the cervical region, there is about a one segment discrepancy between the cord level and the spinous process, in the thoracic region about two segments, and in the lumbosacral region three to four segments. Therefore, the L5 nerve root exiting at the L5–S1 interspace has arisen as a discrete structure at L1–2 and had to traverse the interspaces at L2–3, L3–4, and L4–5 before exiting at L5–S1, sliding laterally all the while. So, the L5 root could be injured by a central disk at L2–3 or L3–4, a posterolateral disk at L4–5, or a far lateral disk or lateral recess stenosis at L5–S1. A posterolateral disk at L4–5 is the most likely culprit, but not the sole suspect. The clinician must correlate the clinical or electromyographic localization of a given root with the radiographic information to deduce the vertebral level involved and the proper course of action.
Cervical roots take a shorter, more direct course and occupy most of the intravertebral foramen. The lumbosacral roots take a long, oblique course, and the lumbosacral foramina are more capacious. Symptomatic radiculopathy is more likely to arise from a smaller disk herniation or osteophytic spur in the cervical region because of these anatomical factors.
With aging and recurrent micro- and macrotrauma, degenerative spine disease develops. This involves both the disk (degenerative disk disease, or DDD) and the bony structures and joints (degenerative joint disease, or DJD). These processes are separate but related. Together, DDD and DJD are referred to as spondylosis .
Small tears in the annulus may cause nonspecific, nonradiating low back pain (LBP). More extensive tears lead to disk bulging or protrusion, in which the disk herniates but remains beneath the PLL. In a disk protrusion, the base is broader than the dome and the herniation generally does not extend above or below the disk space. An extrusion breaches the PLL and allows a full-blown herniation of the NP (HNP) into the epidural space that may extend above or below the disk space. A free fragment refers to disk material that has lost its connection with the main mass of the disk.
Most HNPs in the lumbosacral spine occur in a posterolateral direction; occasionally, they are directly lateral or central (see Fig. 17.2 ). Which nerve roots are damaged depends largely on the direction of the herniation. In the face of disk herniation, the root may be damaged not only by direct compression but also by an inflammatory process induced by discal proteoglycans, ischemia due to pressure, and adhesions and fibrosis.
The anterior elements, vertebral body and pedicles, normally bear 80% to 90% of the weight. As degenerative changes advance with desiccation and loss of disk height, the posterior elements (facets, pars, and laminae) may come to carry up to 50% of the weight-bearing function. This increases the work of the posterior elements and accelerates their degenerative changes. They react to the increased weight-bearing role by becoming hypertrophic and elaborating osteophytes.
Osteoarthritis and synovitis of the facet joints are other sources of problems. In response to the increased loading attendant on loss of disk height and shift of weight bearing posteriorly, the facet joints develop degenerative changes: laxity of the capsule, instability, subluxation, and bony hypertrophy with osteophyte formation. The friction induced by minor instability and microtrauma leads to the formation of osteophytes. In the cervical spine, there is the added element of hypertrophy of the uncinate processes and the development of uncovertebral spurs. Degenerative osteophytes arising simultaneously from the uncus and from the vertebral body end plate region may become confluent and create a spondylotic bar or ridge that stretches across the entire extent of the spinal canal. Like any arthritic joint, the facet may enlarge, impinging on the intervertebral foramen or the spinal canal, especially in the lateral recess. Loss of disk height causes the PLL and the ligamentum flavum to buckle and bulge into the canal. The degenerative changes in the disks and bony elements eventually may culminate in the syndrome of cervical spondylosis, with radiculopathy, myelopathy, or a combination of the two.
All these degenerative changes leave less room for the neural elements. In the sagittal plane, the average cervical spinal cord is about 8 mm and the average cervical spinal canal about 17–18 mm. A sagittal canal diameter less than 10 mm may put the spinal cord at risk. The epidural space is normally occupied primarily by epidural fat and veins. When disk herniations and osteophytes intrude into the space, the resultant clinical manifestations depend in large part on how much room there is to accommodate them. Patients with congenitally narrow canals and those who have undergone past spinal fusion procedures are at increased risk for developing spinal stenosis ( Figs. 17.3 and 17.4 ). Compression of vascular structures may introduce an additional complication of cord or root ischemia.
Because of the varied pathologic processes involved, different types of radiculopathy occur in disk disease and spondylosis. The process is frequently multifactorial, involving some combination of disk herniation and spondylosis. The most straightforward clinical syndrome is unilateral “soft disk” rupture. A similar clinical picture can result from a foraminal osteophyte, a “hard disk” problem. Some patients have soft disk superimposed on hard disk involvement. It is clinically, radiologically, and sometimes surgically difficult to distinguish between soft disk and hard disk involvement. Osteophytes, spurs, and foraminal stenosis are more common than simple soft disk disease in the etiology of cervical radiculopathy (CR). In the series of , soft disk disease (i.e., not present in association with significant spondylosis) was responsible in only 22%; the remainder had hard disk involvement or a combination. A central HNP may compress the spinal cord.
About 75% of flexion and extension occurs at L5–S1 and 20% at L4–L5, but the L5–S1 level has only limited rotation. Approximately 90% of compressive radiculopathies occur at L4–L5 and L5–S1, about evenly divided between the two levels. Despite its higher degree of flexion and extension, the relative lack of rotation at L5–S1 helps increase its stability.
The pathophysiology of radiculopathy is essentially the same regardless of etiology. Root compression due to HNP or spur tends to be concentrated on the distal portion of the root, proximal to the dorsal root ganglion (DRG). As with any nerve compression syndrome, the large myelinated fibers bear the brunt of the damage, and the degree of injury depends on the intensity and duration of the compressive force. Demyelination is the primary change with mild compression; more severe insults produce axon loss. Even with large lesions, the damage is usually only partial. With recovery, remyelination and axon regrowth occur.
Electrodiagnosis will remain a mainstay in the evaluation of suspected radiculopathy for the foreseeable future. The general electrodiagnostic picture in radiculopathy includes normal motor and sensory conduction studies, with the needle electrode examination (NEE) disclosing abnormalities in a myotomal distribution, including the paraspinal muscles. Motor conduction abnormalities should reflect only axon loss, and even this is usually minimal. Sensory studies should be normal except for the occasional occurrence of an abnormal superficial peroneal (SP) sensory response due to an ectopic intraspinal DRG ( ).
The diagnosis of radiculopathy is based primarily on the NEE and primarily on the presence of fibrillation potentials. Normal muscles may contain complex or polyphasic potentials, and it is hazardous to diagnose radiculopathy on motor unit action potential (MUAP) changes in isolation unless there are clear-cut abnormalities in a myotomal distribution. For confident diagnosis, the abnormalities should involve at least two muscles sharing the same myotomal but different peripheral nerve innervations. The examination must be extensive enough to exclude a diffuse process ( ).
The timing of the study in relation to the onset of symptoms is pivotal. It generally requires 7 to 10 days for fibrillation potentials to appear in the paraspinal muscles and 2 to 3 weeks in limb muscles. Reinnervation with disappearance of fibrillation potentials occurs in the same sequence after a variable delay. A study done too early may be normal, a study done too late may also be normal or show only chronic neurogenic MUAP changes but no fibrillations. A study could show fibrillations in the paraspinals only, because limb muscles have not had time for them to develop, or in the limb muscles only because the paraspinals have reinnervated. Thus, depending on the duration of the process, fibrillations could be found in any combination of limb and paraspinal muscles. The paraspinal findings are critical in the evaluation of radiculopathy patients, and it is important to specifically examine the muscles of the multifidus compartment ( ).
EMG has its greatest yield when focused on weak muscles and on the region of likely pathology, so familiarity with the typical clinical picture of cervical radiculopathy and LSR is useful in planning the examination. The clinical evaluation preceding the EMG should screen for nonradicular pathology and determine which root(s) is most likely involved. proposes a streamlined examination of five limb muscles plus paraspinals as having a high diagnostic yield while minimizing patient discomfort and examiner time. The suggested muscles for cervical and lumbosacral root screens and the underlying rationale are discussed extensively in Essentials of Electrodiagnostic Medicine ( ).
There are clear limitations of electromyography (EMG) in the diagnosis of radiculopathy, related to the multiple root innervation of most muscles, the variable relationship between the root level and the vertebral level of injury, the potential for reinnervation by collateral sprouts, the severity of the radicular lesion, and whether it involves axon loss or only demyelination. A normal study does not exclude radiculopathy.
A population-based study of CR provided a wealth of interesting information ( ). The incidence is highest at ages 50 to 54, with a mean age of 47 and a male predominance. Other series have also found a similar mean age and male predominance ( ). In the population-based study, there was a decline in incidence after age 60 (the patients are developing spondylosis and spinal stenosis). There was a history of physical injury or exertion in only 15%; the most common precipitants were shoveling snow or playing golf. The onset was acute in half, subacute in a quarter, and insidious in a quarter, with the majority of patients symptomatic for about 2 weeks prior to diagnosis. Surgery was done in 26%. The disease tends to recur: 31% of patients had a previous history of CR and 32% had a recurrence during follow-up. At last follow-up, 90% of the patients had minimal to no symptoms. Others have noted this favorable long-term prognosis.
Acute radiculopathy due to HNP, soft disk, is seen more often in younger patients. Chronic radiculopathy is seen more often in older patients and typically has components of facet arthropathy and uncovertebral spur as well as disk pathology.
Two classic articles detail the history and examination findings in CR ( ; ). evaluated 100 patients with surgically confirmed single-level cervical radiculopathies ( Table 17.1 ). reviewed 648 cases of surgically treated single-level cervical radiculopathies. Findings in terms of pain radiation and neurologic deficits were similar to those of Yoss et al. The Murphey series did emphasize the occurrence of pain in the pectoral region in 20% of their cases; they opined that neck, periscapular, and pectoral region pain was referred from the disk itself and that arm pain was the result of nerve root compression.
Clinical Finding | Highly Localizing to | Suggestively Localizing to |
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Pain only in neck and shoulder | C5 | |
Presence of scapular/interscapular pain | C7 or C8 | |
No pain below elbow | C5 | |
Pain involving the posterior upper arm | C7 | |
Pain involving the medial upper arm | C7 or C8 | |
Paresthesias limited to the thumb | C6 | |
Paresthesias limited to index and middle | C7 | |
Paresthesias limited to ring and small | C8 | |
Whole hand paresthesias | C7 | |
Depressed triceps reflex | C7 or C8 | |
Depressed biceps and brachioradialis reflexes | C5 or C6 | |
Weakness of spinatus | C5 | |
Weakness of deltoid | C5 or C6 | |
Weakness of triceps | C7 | |
Weakness of hand intrinsics | C8 | |
Sensory loss over thumb only | C6 OR C7 | |
Sensory loss involving middle finger | C7 | |
Sensory loss involving small finger | C8 |
In the Radhakrishnan population-based series, cervicobrachial pain was present at the onset in 98% and was radicular in 65% ( ). Paresthesias were reported by 90%, almost identical to the Yoss series. Pain on neck movement was present in 98%; paraspinal muscle spasm, in 88%; decreased reflexes, in 84% (triceps 50%, biceps or brachioradialis 34%); weakness, in 65%; and sensory loss, in 33% of participants. Employing their criteria, 45% of the patients were judged to have definite CR, 30% probable, and 25% possible. In a Cleveland Clinic series, 70% had motor and sensory symptoms, 12% had motor symptoms only, and 18% had sensory symptoms only ( ).
Localizing information in suspected CR is obtainable from the history, especially from patterns of pain radiation and paresthesias. Radiating pain on coughing, sneezing, or straining during a bowel movement is significant but seldom elicited. Increased pain on shoulder motion suggests nonradicular disease. Relief of pain by resting the hand atop the head is reportedly characteristic of CR (hand on head, Bakody, or shoulder abduction relief sign), but this phenomenon can occur with a Pancoast tumor.
Physical examination in patients with suspected CR should include an assessment of the range of motion (ROM) of the neck and arm, a search for root compression signs, detailed examination of strength and reflexes, a screening sensory examination, and probing for areas of muscle spasm or trigger points ( ). The cervical spine ROM is highly informative. Patients should be asked to put their chin to chest and to either shoulder, each ear to shoulder, and to hold the head in full extension; these maneuvers all affect the size of the intervertebral foramen. Pain produced by movements that close the foramen suggest CR. Pain on the symptomatic side on putting the ipsilateral ear to the shoulder suggests radiculopathy, but increased pain on leaning or turning away from the symptomatic side suggests a myofascial origin. Radiating pain with the head in extension and tilted slightly to the symptomatic side is highly suggestive of CR (Spurling maneuver, foraminal compression test); brief breath holding in this position will sometimes elicit the pain. The addition of axial compression does not seem to add much. Light digital compression of the jugular veins until the face is flushed and the patient is uncomfortable will sometimes elicit radicular symptoms: unilateral shoulder, arm, pectoral, or scapular pain or radiating paresthesias into the arm or hand (Viets or Naffziger sign). This is a highly specific but insensitive finding. An occasional patient has relief of pain with manual upward neck traction. Patients with a globally restricted cervical spine ROM often have extensive degenerative disease. Patients with large disk ruptures or cervical spinal stenosis may have a positive Lhermitte sign on neck flexion.
See Clinical Signs in Neurology: A Compendium for an extensive discussion and video of physical examination signs in CR ( ).
Pain or limitation of motion of any upper extremity joint should signal the possibility of nonradicular disease. The patient should be asked to put the shoulder through a full active ROM, touching the hand to the opposite shoulder and the opposite ear, then reaching behind as high between the scapulae as possible. Any pain or limitation of motion on the symptomatic side suggests bursitis, capsulitis, tendonitis, or impingement syndrome rather than CR as the cause of the patient’s pain.
A focused but detailed strength examination should at least assess the power in the deltoids, spinatus, biceps, triceps, pronators, wrist extensors, abductor pollicis brevis, and interossei. The sensory examination should concentrate on the hand, and particularly assess touch, since the large, myelinated fibers conveying light touch are more vulnerable to pressure injury than the smaller fibers carrying pain and temperature. Because of the extensive overlap of dermatomes, sensory loss in CR is seldom conspicuous. The reflex examination should include not only the standard upper extremity reflexes but the knee and ankle jerks and plantar reflexes as well. Increased lower extremity reflexes and extensor plantar responses suggest myelopathy complicating the radiculopathy.
Based on the foregoing, Box 17.1 outlines the clinical data that favor the diagnosis of CR.
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Several different clinical syndromes may ensue from degenerative spine disease, including simple, single-level radiculopathy; multilevel radiculopathy; cervical myelopathy; cervical radiculomyelopathy; and occasionally a central cord or Brown-Séquard syndrome. Rarely, radiculopathy results from other processes, such as tumor (e.g., neurofibroma, meningioma, metastasis), infection (e.g., Lyme disease, zoster, cytomegalovirus, syphilis, epidural abscess), infiltration (e.g., meningeal neoplasia, sarcoidosis), or ischemia ( ). Diabetes commonly causes a lumbosacral radiculoplexopathy syndrome but can also frequently produce a painful thoracic radiculopathy often confused with herpes zoster and rarely a cervicobrachial radiculopathy ( ). With acute trauma, roots are sometimes injured along with the cervical spine or the BP and in fact may be completely avulsed from the spinal cord in a severe BP injury. Acute and chronic inflammatory radiculoneuropathies commonly involve the roots. Other rare causes include arachnoiditis, root sleeve cyst, epidural lipomatosis, and spinal arteriovenous malformation.
A number of clinical conditions may be confused with CR, primarily brachial plexopathies, entrapment neuropathies, and non-neuropathic mimickers. The more common musculoskeletal conditions causing confusion include shoulder pathology (bursitis, tendinitis, impingement syndrome), lateral epicondylitis, and DeQuervain tenosynovitis. Cervical myofascial pain, facet joint disease, and cervical vertebral body disease can cause neck pain with referred pain to the arm. Patients with cervical strain due to whiplash rarely have radiculopathy. Lyme disease can cause meningitis and radiculitis, producing neck and arm pain. A rare patient with subarachnoid hemorrhage may present with neck pain without headache. Cervical epidural abscess or hematoma may present with neck pain and various neurologic signs. Pain can be referred to the neck, arm, or shoulder from the heart, lungs, esophagus, or upper abdomen.
Clues to the potential presence of an unusual cause of radiculopathy include a history of systemic symptoms such as fever, chills or weight loss, or a history of cancer, immunosuppression or intravenous drug use.
The Quality Assurance committee of the American Association of Electrodiagnostic Medicine has recently reviewed the utility of EMG in the evaluation of patients with CR and formulated a practice parameter addressing this problem ( ). The sensitivity of EMG for detecting abnormalities was in the range of 60% to 70%. The sensitivity is significantly higher in patients with motor involvement than in those with only pain or sensory abnormalities, and the yield increases with increasing severity of disease. Because EMG findings are rarely abnormal in normal subjects, the test is highly specific. There is generally a 65% to 85% correlation of EMG abnormalities with imaging and surgical findings. There is unanimity that C7 root lesions are the most common (±60%), C6 as the next most common (±20%), with C5 and C8 lesions making up about equal proportions of the remainder ( ; ; ; ; ).
The examiner should tailor EMG to probe the muscles most likely to be involved. In the absence of clear clinical direction, one must resort to a generic root screen. Choosing which muscles to study, and how many, has heretofore been a matter of personal opinion and preference. Recent investigations have provided some guidance. concluded that a screen of six limb muscles plus the paraspinals had a yield of 93% to 98%, and that examining more muscles made no significant additional contribution. studied 50 patients with surgically proven single-level cervical radiculopathies. They found stereotyped patterns with C5, C7, and C8 lesions, but a variable pattern with C6 lesions, which could resemble C5 or C7. Patients with a clinical and electrodiagnostic picture of C8 radiculopathy are particularly challenging, as more rostral pathology can mimic C8 radiculopathy and many do not actually have lesions involving the C8 root. In one study of 31 patients, only 16% had C8 root compression ( ).
Plain cervical spine radiographs may show degenerative changes but are of little use in the diagnosis of a specific radiculopathy. Many asymptomatic patients have degenerative changes. Plain films, especially with flexion and extension views, may be useful in patients with more advanced disease to rule out any instability. Computed tomography (CT) is much more useful for visualizing bony detail but does not visualize neural structures unless contrast agent has been instilled (CT myelography). Plain myelography is rarely used. Magnetic resonance imaging (MRI) is the mainstay of diagnosis, although disk herniations are commonly observed on MRI in patients who have no symptoms, particularly in older patients. Several MRI studies have documented that asymptomatic DDD is common. In a study of 1211 healthy volunteers, disk bulging on cervical spine MRI was frequently observed in asymptomatic subjects, including patients in their 20s ( ). Even spinal cord compression and intraparenchymal signal changes were seen in older subjects. Careful clinical and electrodiagnostic correlation therefore remains essential ( ).
Treatment relies on three approaches: mechanical, medicinal, and surgical ( Box 17.2 ). Nerve roots lying in the foramen normally enjoy freedom of movement through a small range. The size of the intervertebral foramen and the lateral recess changes dynamically with neck movement. The mainstay of conservative treatment is to reduce neck movement and increase the size of the foramen.
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A soft cervical collar is usually helpful. For compressive CR, the collar should be worn “backward,” with the high side posterior to maintain the neck in slight flexion and open the foramina. Hard collars cannot be turned around in this fashion and are not as useful for a radiculopathy syndrome as for myelopathy. The soft collar should be worn at night if tolerated; otherwise, the patient should use a cervical pillow. Prolonged use of a cervical collar may weaken neck muscles, so this method of treatment should be limited to a few weeks at most.
Cervical traction for 15 to 30 minutes three times a day is often very helpful; it distracts the spine, opens the foramina, and gives the involved root respite. An over-the-door home traction unit is adequate; referral to a physical therapist is unnecessary. The patient should start with a low weight (5–8 lb) and advance as tolerated to 12 to 15 lb. Too rapid a weight increase may cause neck or jaw soreness and limit compliance. It is theoretically best for the patient to face the door with the neck slightly flexed; the combination of flexion and distraction is more effective in opening the foramen. However, it is difficult to do anything but stare at the door during such treatment; if facing away from the door appears equally efficacious for the individual patient, it is permissible and may improve compliance. Neuroimaging should be done before traction is employed.
Modality physical therapy, or local heat or ice, may provide some relief of the axial pain component, but the effects seldom persist much beyond the individual treatment session. Cervical ROM exercises are of no proven benefit. Nonsteroidal anti-inflammatory drugs (NSAIDs) may decrease the radicular inflammatory component and relieve pain. Other analgesics are often necessary in addition, including occasional narcotics. When the neurologic deficit is moderate (Medical Research Council [MRC] grade 4+/5 in the most involved muscles), a course of oral steroids is reasonable (e.g., prednisone 60–100 mg/day for 7–10 days, tapering over the next 7–10 days) ( ; ). Gabapentinoids are sometimes used in both cervical radiculopathy and LSR, but there is very little evidence to support their effectiveness. Intensive conservative therapy is usually continued for 3 to 6 weeks, and if the patient is no better after that interval, surgical referral should be considered. Muscle relaxants add little and cause side effects of sedation and depression.
Epidural steroid injections have been used for the treatment of radiculopathy, first lumbosacral and later cervical, since the 1950s. Despite this long history, there is a paucity of quality clinical evidence supporting their efficacy. Cervical injections are done via either an interlaminar or transforaminal route. One prospective, randomized trail using transforaminal injections found no difference in outcome between treatment with steroids/local anesthetic or saline/local anesthetic at 3 weeks ( ). A 2015 systematic review of the literature between 1966 and 2014 found only a single high-quality study regarding epidural steroids in cervical disk herniations. A total of 120 subjects received interlaminar injections of either local anesthetic (group I) or local anesthetic and steroid (group II). Significant improvement was seen in 77% in Group I and 80% in Group II ( ).
In a 2007 review of the risks of cervical transforaminal epidural steroids, the authors pointed out the lack of randomized controlled studies supporting their efficacy; that is still the case. They surveyed physician members of the American Pain Society and collected reports of 78 complications, including 16 vertebrobasilar brain infarcts, 12 cervical spinal cord infarcts, and 2 combined brain/spinal cord infarcts, including 13 fatalities. Evidence suggests an embolic mechanism due to inadvertent intra-arterial injection of particulate corticosteroid as the primary mechanism. This risk could potentially be minimized by using the nonparticulate glucocorticoid dexamethasone. Other potential mechanisms include vertebral artery perforation causing dissection/thrombosis and needle-induced vasospasm. The authors conclude that there is a significant risk of serious neurologic injury after cervical transforaminal steroid injections ( ).
Consider surgical referral in patients with an MRC strength of grade 4/5 or worse in any muscle or evidence of myelopathy or excruciating pain unresponsive to conservative treatment. In a population-based study, 26% required surgery. As with epidural steroids, there is scant support in the literature for the efficacy of surgery for CR. Prospective, randomized trials have either not shown a difference in outcome between anterior cervical discectomy and fusion (ACDF) and physical therapy or showed a slight difference favoring surgery early, with no difference at 12–24 months ( ; ; ). A prospective, randomized study with 5- to 8-year follow-up showed that ACDF combined with physiotherapy reduced neck disability and neck pain more effectively than physiotherapy alone ( ).
Some surgeons now prefer anterior cervical disk replacement/arthroplasty (ACDA; artificial cervical disk replacement) over ACDF. Theoretically, ACDA more closely simulates physiologic motion, preserves segmental mobility, and reduces adjacent segment degeneration ( ).
One problem investigators face in determining the effectiveness of any treatment for CR, from cervical traction to surgery, is that the natural history of the condition is toward spontaneous resolution. The typical CR patient is significantly improved by 2 to 3 months. There is a generally favorable long-term prognosis; 90% have minimal to no symptoms on prolonged follow-up. A systematic review and evidence-based clinical guideline on CR from the North American Spine society, in regard to the natural history, offered the following consensus statement: “It is likely that for most patients with cervical radiculopathy from degenerative disorders signs and symptoms will be self-limited and will resolve spontaneously over a variable length of time without specific treatment” ( ).
Although many patients suffer with sciatica at some time, clinically significant LSR occurs in only 4% to 6% of the population. Abnormalities on imaging studies are common in asymptomatic subjects and only loosely associated with symptoms and neurologic examination ( ; ; ). Recent studies using standing MRI may shed light on the matter ( ). There are numerous potential origins for LBP. Most benign self-limited episodes of LBP arise from musculoligamentous structures, and discomfort is localized to the low back region. However, numerous pain-sensitive structures can underlie a clinical episode of LBP: the intervertebral disk, especially the outer fibers of the annulus; the facet joints; other bony structures; and spinal nerve roots. In addition, pain can be referred to the lower back from visceral structures in the abdomen and pelvis. The back may also be involved in systemic diseases, such as spondyloarthropathies.
Involvement of some of these pain-sensitive structures can produce referred pain that radiates to the extremity (buttock, hip, thigh) and can simulate the radiating pain of nerve root origin ( Table 17.2 ). A study of 1293 cases of LBP concluded that referred pain to the lower limb most often originated from sacroiliac and facet joints. Referred pain to the extremity occurred nearly twice as often as true radicular pain and frequently mimicked the clinical presentation of radiculopathies ( ). Investigations have demonstrated that considerable pain can be referred to the buttock and thigh, with disease limited to the disk, the facet joint, or the sacroiliac joint ( ; ; ). A study of 92 patients with chronic LBP concluded that 39% had annular tears or other forms of internal disk disruption as the cause of their pain. No available clinical test differentiated between patients with internal disk disruptions and those with compressive radiculopathy ( ). A similar situation seems to exist with facet joint pain ( ; ). The first suggestion that a patient may have nerve root compression usually comes because of radiating pain into one or both lower extremities. Conservative therapy still usually suffices, even in patients with HNPs, and only 5% to 10% of patients ultimately need surgery ( ). Operative intervention is generally appropriate only when there is a combination of definite disk herniation shown by imaging studies, a corresponding syndrome of radicular pain, a corresponding neurologic deficit, and a failure to respond to conservative therapy.
Disorder | Site of Involvement | Local Pain | Referred Radiating Pain | Radicular Radiating Pain | Pain Increased by | Pain Decreased by | + Straight Leg Raising | Weakest Muscles | Decreased Reflex |
---|---|---|---|---|---|---|---|---|---|
L5 radiculopathy; HNP | L5 root–posterolateral HNP at L4–5 | Back | Buttock, posterior thigh | Buttock, posterior thigh, lower leg, dorsum of foot, big toe | Sitting > standing, cough, sneeze, spinal flexion | Standing, lying | Yes | TA EHL, TP, EDL/EDB, PL, TFL, GMD | MHS |
L5 radiculopathy; lateral recess syndrome | L5 root-lateral recess stenosis | Back | Buttock, posterior thigh | Buttock, posterior thigh, lower leg, dorsum of foot, big toe | Standing, extension | Spinal flexion | No | ||
S1 radiculopathy; HNP | S1 root–posterolateral HNP at L5–S1 | Back | Buttock, posterior thigh | Buttock, posterior thigh, lower leg, dorsum of foot, big toe | Sitting > standing, cough, sneeze, spinal flexion | Standing, lying | Yes | Gastrocnemius, FDL, short toe flexors, decreased toe raises | Ankle, LHS |
S1 radiculopathy; lateral recess syndrome | S1 root-lateral recess stenosis | Back | Buttock, posterior thigh | Buttock, posterior thigh, lower leg, dorsum of foot, big toe | Standing, extension | Spinal flexion | No | ||
Diskogenic pain | Intervertebral disk–torn annulus; internal disruption | Back | Buttock, posterior thigh | None | Sitting, spinal flexion | Lying | No | No weak muscles, possible splinting due to pain | None |
Musculoligamentous pain | Musculoligamentous structures of low back | Back | Buttock, posterior thigh | None | Walking, bending, stooping, minor movements | Sitting or lying | Negative or equivocal, not radiating | No weak muscles | None |
Nonorganic | Back + any other; often back + neck | None | No consistent pattern | No consistent pattern | Variable and nonorganic | None | None |
reviewed the information that could be obtained from the history and physical examination in patients with LBP. They suggest trying to answer three basic questions: Is there a serious, underlying systemic disease present? Is there neurologic compromise that might require further evaluation? Are there psychological factors leading to pain amplification? Factors that suggest the possibility of underlying systemic disease include a history of cancer, unexplained weight loss, pain lasting longer than 1 month, pain unrelieved by bed rest, fever, focal spine tenderness, morning stiffness, improvement in pain with exercise, and failure of conservative treatment.
The utility, or lack thereof, of various physical examination findings has been studied. The straight leg raising (SLR) test remains the mainstay in detecting radicular compression. The test is performed by slowly raising the symptomatic leg with the knee extended. Tension is transmitted to the nerve roots between about 30 and 70 degrees and pain increases. Pain at less than 30 degrees raises the question of nonorganicity, and some discomfort and tightness beyond 70 degrees are routine and insignificant. There are various degrees or levels of positivity. Ipsilateral leg tightness is the lowest level, pain in the back is more significant, and radiating pain in the leg is highly significant. When raising the good leg produces pain in the symptomatic leg (crossed SLR sign), the likelihood of a root lesion is very high.
The positivity of the SLR should be the same with the patient supine or seated. If a patient with a positive supine SLR does not complain or lean backward when the extended leg is brought up while in the seated position (e.g., under the guise of doing the plantar response), it is suggestive of nonorganicity. The SLR can be enhanced by passively dorsiflexing the patient’s foot just at the elevation angle at which the increased root tension begins to produce pain. A quick snap to the sciatic nerve in the popliteal fossa just as stretch begins to cause pain (bowstring sign, or popliteal compression test) accomplishes the same end. Patients with hip disease have pain on raising the leg whether the knee is bent or straight; those with root stretch signs have pain only when the knee is extended. Pain from hip disease is maximal when the hip is flexed, abducted, and externally rotated by putting the patient’s foot on the contralateral knee and pressing down slightly on the symptomatic knee ( fabere test). There are other procedures for checking the sacroiliac joints.
See Clinical Signs in Neurology: A Compendium for an extensive discussion and video of physical examination signs in LSR ( ).
The neurologic examination should include assessment of power in the major lower extremity muscle groups, but especially the dorsiflexors of the foot and toes, and the evertors and invertors of the foot. Plantar flexion of the foot is so powerful that manual testing rarely suffices. Having the patient do 10 toe raises with either foot is a better test. Sensation should be tested in the signature zones of the major roots. The status of knee and ankle reflexes is informative about the integrity of the L3–4 and S1 roots. There is no good reflex for the L5 root, but the hamstring reflexes are occasionally useful. The medial and lateral hamstrings are both innervated by both L5 and S1, but the medial hamstring tends to be more L5 and the lateral more S1. An occasional L5 radiculopathy produces a clear selective diminution of the medial hamstring reflex. Rarely, an L5 radiculopathy will cause a deceased peroneal reflex (see http://neurosigns.org/wiki/Peroneal_reflex ). In a patient with absent ankle jerks and a question of neuropathy, loss of the lateral hamstring reflex with preservation of the medial helps confirm radicular disease. Preservation of the lateral hamstring jerk with an absent ankle jerk suggests a length-dependent process (i.e., peripheral neuropathy).
Studies have found that only 8 of 27 physical tests investigated successfully discriminated between patients with chronic LBP and normal control subjects. The eight useful tests were pelvic flexion, total spinal flexion, total extension, lateral flexion, SLR, spinal tenderness, bilateral active SLR, and sit-up ( ). Tests for nonorganicity (Waddell signs) are very useful. Pain during simulated spinal rotation, pinning the patient’s hands to the sides while passively rotating the hips back and forth (no spine rotation occurs as shoulders and hips remain in a constant relationship), suggests nonorganicity. This is also suggestive with a discrepancy between the positivity of the SLR between the supine and seated position, pain in the back on pressing down on top of the head, widespread and excessive “tenderness,” general overreaction during testing, and nondermatomal/nonmyotomal neurologic signs. The presence of three of these signs suggests, if not nonorganicity, at least embellishment ( ).
The major radicular syndromes include HNP, lateral recess stenosis, and spinal stenosis with cauda equina compression. Virtually all patients with radiculopathy have sciatica. The odds of a patient without sciatica having radiculopathy have been estimated at 1:1000 ( ). The details of the sciatica are noteworthy, including the exact pattern of radiation, influence of body position and movement, and presence or absence of neurologic symptoms.
With HNP or lateral recess stenosis, leg pain usually predominates over back pain. With HNP, the pain is typically worse when sitting, better when standing, better still when lying down, and generally worse in flexed than extended postures—all reflecting the known changes in intradiscal pressure that occur in these positions. With lateral recess stenosis, the pain is worse with standing or walking and relieved by sitting with the torso flexed or by lying down. Patients with HNP tend to have a positive SLR, but those with recess stenosis do not. The essence of the recess stenosis picture, then, is pain on standing, lack of pain on sitting, and a negative SLR. The essence of the HNP picture is pain worse on sitting, lessened with standing, and a positive SLR. Patients with HNP are usually in the 30 to 55 years age range; those with lateral recess stenosis are a bit older. As with CR, pain may exacerbate with cough, sneeze, or Valsalva maneuver.
As patients mature into the seventh decade and beyond, the liability to disk rupture decreases, but degenerative spine disease attacks in a different form. Osteophytic spurs and bars; bulging disks; thickened laminae and pedicles; arthritic, hypertrophied facets; and thickened spinal ligaments all combine to narrow the spinal canal and produce the syndrome of spinal stenosis. An extension posture contributes to spinal stenosis by causing narrowing of the foramina and dorsal quadrants and buckling of the ligamentum flavum. Narrowing of the canal compresses neural and possibly vascular structures. Flexing the spine, as by leaning forward, stooping over, or sitting down, opens the canal and decreases the symptoms.
Patients with spinal stenosis and neurogenic claudication experience pain, weakness, numbness, and paresthesias/dysesthesias when standing or walking. Symptoms decrease with sitting or bending forward. An occasional patient will have a bizarre symptom, such as spontaneous erections or fecal incontinence brought on by walking. Differentiation from vascular claudication is made by the wide distribution of symptoms, the neurologic accompaniments, and the necessity to sit down for relief. Vascular claudication tends to produce focal, intense, crampy pain in one or both calves, and the pain subsides if the patient just stops and stands. Patients with vascular claudication have even more symptoms walking uphill, because of the increased leg work. Neurogenic claudication may decrease when walking uphill because of the increased spinal flexion in forward leaning. Patients with vascular claudication have as much trouble riding a bicycle as walking because of the leg work involved, whereas forward flexion on the bicycle opens up the spinal canal, allowing patients with neurogenic claudication to ride a bike with greater ease than they can walk.
An investigation of 68 patients with lumbar spinal stenosis found that pseudoclaudication, or neurogenic claudication, was the most common symptom, producing pain, numbness, or weakness on walking, frequently bilaterally and usually relieved by flexing the spine. Mild neurologic abnormalities occurred in a minority of patients. EMG showed one or more involved roots in 90% of patients ( ).
The vast majority of LSRs are due to degenerative spine disease. Other disease processes can occur and may require exclusion. As with CR, patients may develop back pain and radiculopathy with epidural abscess or hematoma, diffuse meningeal neoplasia, diabetes, and other conditions ( ).
Plain lumbosacral spine films are rarely helpful except in the setting of acute trauma or suspected infection or malignancy. Plain CT may be useful in patients who are unable to undergo MRI; when combined with intrathecal contrast, CT is highly accurate for detecting nerve root compression (CT myelography). Plain myelography is sometimes useful, particularly in patients unable to undergo MRI because of metallic fixation and in those too obese to fit in an MRI scanner. MRI is the imaging procedure of choice in LSR, again with the caveat that many asymptomatic patients have disk disease on MRI that is not clinically relevant ( ).
Investigators face the same problems in determining the effectiveness of treatment for LSR as for CR, since symptoms of LSR due to disk herniation are typically self-limited. In patients with underlying spondylosis due to degenerative arthritis, radicular symptomatology may wax and wane, making the long-term prognosis less favorable than with disk herniation.
Studies have clearly shown that bed rest is not efficacious in patients with nonspecific or mechanical LBP ( ). There is less information about the role of bed rest in acute LSR, and brief, judicious bed rest may still be useful for short-term symptom control in patients who are in acute, severe pain. At the very least, if the patient remains up and active, he or she should avoid activities such as bending or lifting, which are known to increase intradiscal pressure. Patients often find particular positions that are comfortable and particular activities to avoid.
Any benefit from agents such as benzodiazepines and cyclobenzaprine are probably due more to the drowsiness induced, helping to keep the patient inactive, than to any muscle relaxant effects. NSAIDs may be useful both for pain control and to help reduce acute radicular inflammation, although trials have not substantiated their usefulness compared to placebo ( ). Opioids may be needed for pain relief in the acute situation. A short course of oral steroids is sometimes useful. Supportive evidence is marginal ( ; ). Drugs used to treat neuropathic pain, such as tricyclic antidepressants, gabapentin, and similar agents, may be useful for the management of chronic radiculopathy, but there is little evidence that they are helpful in the acute situation.
Many studies have been done regarding epidural steroids for LSR and spinal stenosis, leading in turn to a number of meta-analyses ( ; ; ; ). The conclusion in general is that any effect of epidural steroids is short lived and the treatment effect is small. The systematic review and meta-analysis by concluded that there was effectiveness for radiculopathy but the benefits were small and not sustained, and that there was no effectiveness for spinal stenosis. The 2016 systematic review and meta-analysis by concluded that lidocaine alone and lidocaine in conjunction with steroids were equally effective. In six studies with 649 patients, there was no difference in improvement comparing lidocaine alone to lidocaine with steroids at 3 or 12 months. Epidural steroids administered with sodium chloride solution were ineffective. This raises the possibility that any benefit from steroids may arise through some mechanism other than an anti-inflammatory one and that perhaps epidural injections should use local anesthetics alone, as was routinely the practice between 1901 and the early 1950s.
Physical therapy such as back exercises should probably be avoided with an acute painful radiculopathy. After the acute stage has subsided, physical therapy may certainly be useful. However, if back exercises reproduce radicular pain, they should be stopped immediately. Numerous other nonoperative treatments are occasionally used, although demonstration of effectiveness in randomized trials is generally lacking. These treatments include transcutaneous electrical nerve stimulation, acupuncture, massage, and spinal manipulation.
The vast majority of patients with acute LSR improve with time and conservative management, even when the disk herniation remains visible on MRI. Surgical referral should be prompt if the patient develops any evidence of cauda equina syndrome. Whether patients with more routine LSR benefit from surgery remains controversial. There is no evidence that early surgery, in the absence of a severe or progressive neurologic deficit, improves the outcome for radiculopathy due to lumbar disk herniation with or without spinal stenosis. Many patients with a minor motor deficit, such as a mild foot drop, recover with nonsurgical treatment.
If surgery is required, a number of techniques are currently employed, including traditional open laminectomy and discectomy, microdiscectomy with hemilaminectomy, and minimally invasive techniques such as percutaneous discectomy, laser discectomy, percutaneous endoscopic discectomy, microendoscopic discectomy, and radiofrequency nucleoplasty ( ). Studies comparing surgery to nonsurgical management for radiculopathy generally show that operated patients improve more quickly but that outcomes are similar within 2 years ( ; ). Nonspecific LBP with DDD associated with subacute or chronic LBP without radicular symptoms is another topic altogether.
Numerous pathologic processes may affect either the BP or the LSP ( Box 17.3 ). Whereas the vast majority of radiculopathies are due to compression, the plexopathies may be caused by a number of different pathologic processes. The complex anatomy makes evaluation challenging ( Fig. 17.5 ). The most common and clinically important of the BP disorders include neuralgic amyotrophy (NA) (acute brachial plexopathy or brachial plexitis); trauma, such as with missile and stab wounds or motor vehicle (especially motorcycle) accidents; neoplasms; postradiation plexopathy; obstetric palsies; postsurgical plexopathy; the “stinger” or “burner” phenomenon that frequently affects football players, which is likely a mild form of plexus injury; and TOS. Other causes include external compression (e.g., backpack or rucksack palsy), compression from an internal process (e.g., encroachment on the lower BP from a Pancoast tumor), or involvement in systemic processes such as systemic lupus erythematosus (SLE) or sarcoid, or iatrogenic plexopathy during cardiac surgery. The BP may rarely be involved in a number of other conditions, including lupus, lymphoma, Ehlers-Danlos syndrome, and infectious or parainfectious disorders. Some of these processes are by nature progressive.
Immunizations
Serum sickness
Botulinum toxin
Interleukin 2
Interferon
Heroin
Lyme disease
Erlichiosis
Herpes zoster
HIV infection
Epstein-Barr virus infection
Cytomegalovirus infection
Parvovirus infection
Yersiniosis
Hereditary neuralgic amyotrophy
Hereditary neuropathy with liability to pressure palsies (HNPP)
Ehlers-Danlos syndrome
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