Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Cervical Disc Herniation
Summary of Key Points
-
Cervical disc herniation is a common cause of neck pain, radiculopathy, and cervical myelopathy. Risk factors include male gender, increasing age, white race, cigarette smoking, heavy lifting, and occupation.
-
Disc herniations results from traumatic, overuse, or age-related weakening of the annulus fibrosus and subsequent herniation of the nucleus pulposus through the injured annulus. This can cause compression of the posteriorly based neural elements.
-
Clinical manifestations of disc herniation include cervicalgia (nonradiating neck pain), cervical radiculopathy (radiating pain, weakness, or sensory changes in a dermatomal pattern), or cervical myelopathy (constellation of symptoms resulting from cord compression).
-
Although cervical dermatomes have been well established, a high degree of variability and overlap can occur at the nerve root level. Furthermore, anomalous anatomy in the brachial plexus (e.g., prefixed and postfixed plexuses) and distal nerve anastomoses may confound the clinical picture.
-
The natural history of cervical radiculopathy alone is generally favorable. Although 26% of patients may eventually require surgery, the majority of patients will experience gradual and spontaneous resolution of symptoms with conservative management alone, with regression of the disc herniation noted on repeat imaging in many cases.
-
In general, surgery is indicated in the setting of a confirmed cervical disc herniation causing cervical nerve root compression on magnetic resonance imaging or computed tomography myelogram with associated signs and symptoms of neurological dysfunction that have failed a 6- to 12-week course of nonoperative management.
-
Progressively worsening motor deficit may warrant more urgent surgery. Furthermore, surgery is recommended in cases of imaging-confirmed cervical spinal cord compression with clinical evidence of moderate to severe cervical myelopathy, regardless of time course of symptoms.
-
The most well-recognized surgical interventions for symptomatic disc herniation include anterior cervical discectomy and fusion, posterior foraminotomy, and cervical disc arthroplasty.
-
The incidence of all-cause complications in the setting of anterior cervical spine surgery has been reported at rates of up to 19.3%. A 9.0% rate of complications in the setting of posterior cervical surgery has been cited.
Background
The cervical spine allows for multidirectional motion, including flexion, extension, side bending, and axial rotation, which can become limited with age or secondary to various cervical spine pathologies. , Motion occurs in the subaxial spine through the uncovertebral joint (joint of Luschka), which is a specialized fibrous joint composed of two vertebral bodies and an intervertebral disc, and through the posterior facets, which are specialized synovial joints.
The intervertebral disc is composed of an inner gelatinous core, known as the nucleus pulposus, and an outer fibrous ring, known as the annulus fibrosus. The nucleus pulposus is predominantly composed of type II collagen, has a low collagen to proteoglycan ratio, and is characterized by its ability to resist compression. The annulus fibrosus is composed predominantly of type I collagen, has a high collagen to proteoglycan ratio, and is characterized by high tensile strength. This motion is modulated and restrained by both static and dynamic structures. Static structures include the anterior longitudinal ligament, posterior longitudinal ligament (PLL), ligamentum flavum, and osseous architecture. Dynamic structures include the complex paraspinal and interspinous musculature.
Acute trauma or overuse injury, age-related changes in the composition of the intervertebral disc, and genetic predispositions can result in weakening of the annulus fibrosus and herniation of the nucleus pulposus through the injured annulus. This can cause compression of the neural elements centrally in the spinal canal or laterally in the neuroforamen. The resulting clinical manifestation can be categorized as cervicalgia (nonradiating neck pain), cervical radiculopathy (radiating pain, weakness, or sensory changes in a dermatomal pattern), or cervical myelopathy (constellation of symptoms resulting from cord compression). The purpose of this chapter is to review the pathophysiology of, clinical evaluation of, and surgical approaches to cervical disc herniation.
Pathophysiology and Diagnosis
Cervical disc herniation is a common cause of neck pain, radiculopathy, and cervical myelopathy. Risk factors include male gender, increasing age, white race, cigarette smoking, heavy lifting, and occupation. There is evidence to suggest that female gender may lead to a higher risk in certain populations, such as military recruits. Furthermore, high-risk occupations and activities may include those that require the operation of vibrating equipment, such as those that require a lengthy time period spent driving a vehicle, or repetitive loadbearing, which can occur in activities such as diving. The incidence of cervical disc herniation has been estimated at 18.6 per 100,000 individuals. Spondylosis at the cervical spine seems to predominate at the C4‒C5, C5‒C6, and C6‒C7 levels, , although disc herniation can occur at any level. Many disc herniations are asymptomatic.
Compression of the spinal cord can cause a constellation of symptoms known as cervical myelopathy. Cervical myelopathy is a clinical diagnosis that includes a myriad of symptoms and clinical findings, including gait imbalance, clumsiness with fine motor tasks in the upper extremities, and hyperreflexia in the upper and lower extremities. It is not unusual to elicit signs of long tract injury with positive Hoffman sign, Babinski, or even clonus in patients with significant compression of their spinal cord. , It is important, however, to understand that the absence of these signs does not preclude the diagnosis of cervical myelopathy.
Radiculopathy typically results from compression of the exiting nerve root and may present with arm pain, sensory deficits, neck pain, reflex deficits, or motor deficits. Coughing and sneezing can exacerbate underlying radicular symptoms and can provide helpful insight into the diagnosis. Clinical signs such as the shoulder abduction sign, which can relieve the radicular symptoms, and the Spurling test, which can elicit the radicular symptom, are also helpful in making the diagnosis.
Although cervical dermatomes have been well established, it is crucial to understand that a high degree of variability and overlap can occur at the nerve root level. Furthermore, anomalous anatomy in the brachial plexus (e.g., prefixed and postfixed plexuses) and distal nerve anastomoses may confound the clinical picture. The use of electromyelography, nerve conduction studies, selective nerve root blocks, and epidural steroid injections can aid in the clinical correlation between a patient’s symptoms and radiographic findings.
Although less frequent, high cervical radiculopathies (C2, C3, and C4) can present with suboccipital headache or pain radiating to the temporal, retroorbital, or retroauricular regions of the cranium. ,
Case Example
A 50-year-old female patient presents with pain radiating from her neck to her right middle finger with a concomitant subjective decrease in sensation in the same distribution. Physical examination demonstrates 4‒/5 motor strength in the right triceps muscle ( Fig. 136.1 ).
Management
Surgical indications for cervical disc herniations differ based on whether the patient is experiencing radiculopathy without neurological deficit or if there is a concomitant deficit secondary to nerve root or spinal cord compression. The natural history of cervical radiculopathy alone is generally favorable. In a population-based study from Rochester, Minnesota, 26% of 561 patients with cervical radiculopathy underwent surgical intervention within 3 months of diagnosis, with radicular pain, sensory deficit, and objective muscle weakness being the primary predictors for proceeding to operate. However, the majority of patients had gradual resolution of their symptoms spontaneously with conservative management alone, with regression of the disc herniation noted on repeat imaging in many cases. , Conservative treatment generally consists of a course of physical therapy, analgesic medications (i.e., nonsteroidal antiinflammatory drugs, opioids), and corticosteroid injections.
If conservative treatment is unsuccessful in relieving symptoms, surgery can be considered. In general, surgery is indicated in the setting of a confirmed cervical disc herniation causing cervical nerve root compression on magnetic resonance imaging (MRI) or computed tomography (CT) myelogram with associated signs and symptoms of neurological dysfunction after a 6- to 12-week course of nonoperative management with minimal improvement. Progressively worsening motor deficit can represent a more urgent need for surgery. Finally, surgery is recommended in cases of imaging-confirmed cervical spinal cord compression with clinical evidence of moderate to severe cervical myelopathy, regardless of time course of symptoms.
Surgical Approach
Posterior Cervical Foraminotomy
Dorsal exposure for cervical disc herniations presents a few advantages over a ventral approach. Specifically, the posterior approach can be used to access a lateral disc herniation without the need for fusion or any instrumentation. Posterior foraminotomy with partial resection of the medial facet joint, originally described by Frykholm and Scoville, has become the standard approach for these types of herniations. Central disc herniations and so-called “hard” discs should be approached ventrally. Regarding technique, the dorsal approach can be performed either open or through a minimally invasive surgery (MIS) approach via a tubular retractor. The patient can be positioned either prone or in a seated position in a Mayfield head holder. A parasagittal incision is made, and the paraspinal muscles are dissected off the lamina and medial spinous process before an open retractor is placed; in the case of an MIS approach, sequential dilators are docked onto the lamina and medial facet, and a tubular retractor is inserted. A hemilaminotomy is then performed above and below the level of the lesion, with removal of the medial facet joint with a high-speed drill. The underlying ligamentum flavum is then detached and removed using a combination of curettes and Kerrison rongeurs until the underlying lateral dural margin and nerve root origin can be visualized. Epidural venous bleeding can be extensive, and thorough hemostasis should be achieved to allow for appropriate visualization of the neural elements. Adequate exposure of the nerve root is also important, as this can often be mistaken for extruded disc material.
The disc is generally located immediately caudal to the nerve root, right at the axilla. The root itself can be gently retracted superiorly to allow for access to the disc herniation. An incision is then made in the PLL with a knife. Oftentimes, the herniated disc fragment can be extruded through the incised PLL with some downwards pressure. Removal of this disc fragment usually provides additional space so that the foramen can be further explored and decompressed as needed. Further discectomy is usually not necessary and is not recommended, as further visualization of the disc space would require significant retraction of either the nerve root or spinal cord, which increases the risk for neurological injury. Upon completion of the decompression, the retractor is then removed, and the underlying fascia and tissue are closed.
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here
