Differential Diagnosis of Surgical Disorders of the Spine

Degenerative Disease of the Cervical Spine

Neck pain is among the top five diseases in the United States contributing to years lived with disability. Studies have estimated a mean prevalence of 48.5%, suggesting that half of all individuals will experience clinically significant neck pain throughout their lifetime. Prevalence tends to be higher amongst females, with a peak incidence in middle-aged individuals. Neck pain is often associated with comorbid health conditions such as psychological complaints, including serious mental illness and modifiable risk factors. In addition, patients may have nonmodifiable risk factors, such as a history of prior injury, occupations, or hobbies that put them at greater risk. Sports-related injuries from race car driving, wrestling, and ice hockey have the highest incidence. Patients present with a variety of complaints, and it can be difficult to differentiate among the many possible causes of neck pain ( Box 66.2 ). Patients present on a spectrum from mechanical or axial spine pain, to radiculopathy (pain or other symptoms that follow a dermatomal or myotomal distribution), to myelopathy (symptoms related to spinal cord pathology).

Neck pain may present as acute (<6 weeks), subacute (<3 months), or chronic (>3 months). History should focus on severity of symptoms, preceding injuries, associated symptoms, and qualities that may point to a specific type of neck pain. Broadly speaking, neck pain can be mechanical (originating from the spine and its supporting structures, such as vertebrae, ligaments, discs, and muscles), neuropathic (originating from the nerve root and/or spinal cord), or many times a combination of the two. Studies suggest that approximately 43% of patients present with nonneuropathic pain (7% with predominantly neuropathic, and 50% with a combination).

History should also focus on progression of symptoms and quality-of-life measures. Often, mechanical pain from degenerative disease will progress over time to neuropathic pain or neurological deficits from progressive central/foraminal stenosis, disc herniation, and so on. The rate of this progression may greatly impact your treatment algorithm and when to consider surgical management of neck pain. Impact on quality of life may also impact treatment options under consideration. Natural history suggests that most patients presenting with acute neck pain will experience symptom resolution within 2 months. However, as many as 50% of patients may continue to have ongoing discomfort or recurrence of symptoms within 1 year. This can include a recurrence of mechanical neck pain, progression to radicular symptoms, or myelopathy.

Although many studies have investigated the natural course of lumbar spinal stenosis with radiculopathy, few studies exist delineating the natural course of cervical radiculopathy. Much like those reported for lumbar disc herniations, cervical herniations can go on to exhibit significant resorption with conservative treatment, with studies reporting rates of resorption of 40% to 76%. ^, In a large retrospective epidemiological study from the Mayo Clinic, even though ongoing symptoms or recurrence of symptoms were somewhat frequent, 90.5% of patients who initially presented with cervical radiculopathy were experiencing mild or no pain at a mean follow-up of 5.9 years. A systematic review by Wong et al. found that the prognosis for cervical radiculopathy was favorable. Patients experienced significant clinical improvements in the first 4 to 6 months, with ongoing improvement at 2 to 3 years from initial presentation.

Perhaps our most important tool in identifying where people fit on the spectrum of degenerative disease of the cervical spine, from mechanical pain to radiculopathy to myelopathy, is the physical exam. The presence or absence of certain examination findings also tends to dictate next steps in the diagnostic workup. Most patients will present with some aspect of pain. This can be myofascial pain along the paraspinal region and at trigger points, axial neck pain directly along the spinal column, or radicular pain that radiates along a nerve root distribution. Paraspinal tenderness points toward myofascial pain or facet joint arthropathy. While most radicular pain is referred to the upper extremities, it is important to remember that high cervical spine nerve root compression can also present with occipital headaches or posterior auricular pain. Certain physical examination maneuvers can exacerbate radicular pain. The Spurling test reproduces radicular symptoms with lateral flexion, extension, and rotation of the cervical spine toward the affected side. Coughing and other Valsalva maneuvers can also suggest discogenic or radicular pain. ^, With cervical myelopathy, patients may report pain or an electrical sensation that radiates into the body, upper extremities, and possibly the lower extremities with cervical spine flexion. This is referred to as the Lhermitte sign. Both of these tests are highly specific for cervical spine pathology.

Most patients with degenerative cervical spine disease will also present with some amount of restriction in range of motion (ROM). This is most commonly seen as a gradual loss of extension. Patients will frequently develop a progressive loss of lordosis or eventual kyphosis of the cervical spine. In severe cases they may present with a chin-to-chest deformity.

It is important to look for neurological signs that might point toward significant spinal cord compression indicative of cervical myelopathy. The presence or absence of upper and lower motor neuron signs can help distinguish radiculopathy from myelopathy ( Table 66.2 ). Lower motor neuron signs will be present in patients with radiculopathy, as compression is occurring at the level of the spinal nerve root. These signs include hyporeflexia, dermatome paresthesias, and myotomal weakness. Often these occur unilaterally.

In contrast, myelopathic patients, who have compression at the level of the spinal cord, will present with upper motor neuron signs. Signs and symptoms are often bilateral. Although they may share symptoms such as pain and numbness and weakness in a specific distribution, they may present with hyperreflexia in contrast to lower motor neuron dysfunction. One must take into account other medical comorbidities and conditions that can impact examination of the reflexes. For instance, hyperreflexia may be masked in patients with diabetes and other diseases impacting the peripheral nervous system. In the myelopathic patient, physical examination findings such as positive Hoffmann/Tromner reflex, inverted radial reflex, multibeat or sustained ankle clonus, positive Babinski reflex, or a crossed adductor reflex suggests upper motor neuron dysfunction.

Other upper motor neuron signs include clumsiness of the hands and feet, as well as gait imbalance. Gait patterns of instability and spasticity may be present in the patient with myelopathy and can often be the first presentation. Cranial nerve examination including the jaw jerk reflex (among others) may help differentiate intracranial from cervical spine pathology.

Degenerative Disease of the Lumbar Spine

Lower back pain is the most common musculoskeletal problem globally. It is estimated that 70% to 85% of the population will experience lower back pain in their lifetime. Spine problems have been cited as one of the most common causes of disability in people under the age of 50 years. Lower back pain has contributed to approximately $300 billion in disability-related costs for medical care and lost productivity costs annually in the United States. It is the second most common cause for healthcare visits. As in patients with neck pain, back pain is associated with multiple comorbidities. Many modifiable and nonmodifiable risk factors have been identified, including a significantly higher incidence of mental illness, as well as smoking and excessive alcohol intake. The chronicity and duration is often debated, but overall a majority of patients’ lower back pain resolves by 1 year, regardless of treatment. Back pain is a common and pervasive issue. Multiple studies have shown that the majority of patients make a full recovery with no residual deficits. However, approximately 10% to 15% of those affected will go on to experience chronic back pain.

Lower back pain has many potential sources, including the intervertebral discs, facet joints, vertebrae, neural structures, muscles, ligaments, and fascia, making a thorough history and physical examination a necessary focus for each patient. The most common etiologies of back pain can be elicited from thorough history-taking. Generally, back pain can be broken into categories based on etiology, including musculogenic, radicular, discogenic, neurogenic, and mechanical pain. It is important to differentiate one from another, as etiology will dictate treatment. Back pain may present as acute (<4 weeks), subacute (4–12 weeks), or chronic (>12 weeks). The history should delineate the location and timing/onset of the pain, characteristics of the pain, presence or absence of neurological signs/symptoms, and presence of systemic signs and symptoms referred to as“red flag” symptoms (see Box 66.1 ).

A physical examination in conjunction with a thorough history in many cases is enough to delineate the etiology of the patient’s back pain. The physical examination should always include basic gait evaluation, inspection of upright posture, palpation of the paraspinal structures, motor and sensory examination of the upper and lower extremities, reflexes including assessment for pathological reflexes, as well as a physical examination of the hips, knees, and ankles. Additional spine-specific examination maneuvers include straight-leg raise, femoral nerve stretch, and standing extension test.

Musculogenic pain is paraspinal soft tissue pain associated with sprains and spasms. Pain tends to be exacerbated by activity and is typically characterized by stiffness and discomfort with bending motions. There is often palpable tenderness on examination. Discogenic pain is back pain associated with intervertebral disc degeneration without herniation or anatomical deformity, and can be somewhat controversial. Pain is typically centrally located, but may have referral patterns. Intervertebral disc pain is typically worse with sitting or other postures that increase loading of the disc, and tends to be mechanical and positional. In contrast, axial back pain associated with prolonged standing and lumbar extension may be as a result of facet arthropathy and/or spondylolisthesis (with or without pars defect), as the posterior elements are loaded in those positions.

Lumbar radiculopathy is the term used to describe pathology associated with a lumbar spinal nerve root, typically related to compressive pathology. Radicular symptoms include pain, paresthesias, weakness, and/or reflex changes in a spinal nerve root distribution. It may be accompanied by postures and/or activities that improve or worsen symptoms. Positional improvement or worsening of radicular symptoms may help direct further workup or treatment. Myotome, dermatome, and deep tendon reflex examination can help differentiate central nervous system (CNS) lesions from lumbar nerve root and peripheral nerve pathology. While a lumbar radiculopathy can be suggested based on history and physical exam, the underlying source of degenerative radiculopathy often requires additional advanced modalities to help determine the source (intervertebral disc protrusion, facet synovial cyst, foraminal stenosis from degenerative disc space collapse, facet arthropathy, osteophyte formation).

Lumbar spinal stenosis can present with a myriad of signs and symptoms. Neurogenic claudication is a term used to describe bilateral lower extremity neurological signs and symptoms caused by lumbar spinal stenosis and compression of the cauda equina. Certainly, many pathological processes can compress the cauda equina; however, the most common cause is degenerative. This may include degenerative disc bulging, facet arthropathy, hypertrophy of the ligamentum flavum, and hypermobility/instability. Lumbar neurogenic claudication must be differentiated from lower extremity vascular claudication. One of the main differentiating factors is that neurogenic claudication symptoms change with spine posture. For example, the standing lumbar extension test may reproduce symptoms in the patient with neurogenic claudication, but not vascular claudication. Lumbar spine flexion tends to improve symptoms of neurogenic claudication as the central canal and foraminal dimensions increase and lessen compression of the neurological structures.

Trauma

In the setting of traumatic injury to the spine, injuries can range from the very minor fracture or soft-tissue injury that requires only observation for treatment to those that lead to a complete spinal cord lesion. Most of these patients are evaluated in a trauma center where injuries are diagnosed and managed. However, there are a few pathological entities that warrant discussion, as they can be seen many years after a spinal cord injury. Those include posttraumatic syringomyelia (PTS) and Charcot spine (spinal neuroarthropathy). Recognizing the history, signs, and symptoms can help lead to a timelier diagnosis and treatment.

Posttraumatic Syringomyelia

PTS is a term used to describe a condition in which a cavity or cyst forms within the spinal cord after a traumatic spinal cord injury. PTS is thought to develop within 5 years of the spinal cord injury, but onset can range from several months to years/decades after the initial injury. ^, In patients with traumatic spinal cord injury, the prevalence of symptomatic PTS is approximately 4%, whereas the prevalence of asymptomatic PTS may be as high as 28%. Although PTS is rare, it has become an increasingly recognized cause of morbidity in patients with traumatic spinal cord injury.

The more common presenting signs/symptoms of PTS include pain, numbness, and motor weakness. Typically, there is a progressive neurological deterioration related to syrinx expansion centered about the original traumatic injury. The deterioration can be in the form of an ascending sensory level and loss of motor function above the original lesion. Neurological deterioration has the potential to progress rapidly over the course of weeks or months.

Charcot Spine

Charcot spine is a degenerative spinal neuroarthropathy. A more common type of neuroarthropathy is the “Charcot” foot; for example, in a patient with diabetes. The Charcot foot is related to a peripheral neuropathy, whereas spine-related neuroarthropathy is typically caused by a spinal cord injury. The pathophysiology is thought to be the result of loss of protective proprioceptive and nociceptive afferent input. This can lead to repeated microtrauma that ultimately begins to break down the intervertebral articulations. Approximately 93% of reported cases of Charcot spine are in patients with a complete lesion, and most Charcot spine cases occur below the T10 level. It is a relatively rare condition, presenting in about one of every 220 patients with spinal cord injury. The time interval between spinal cord injury and the onset of Charcot spine can range from 2 years to greater than 30 years.

Although traumatic spinal cord injury is the most common cause of Charcot spine, other conditions such as congenital insensitivity to pain, Friedreich ataxia, chronic inflammatory demyelinating polyneuropathy, transverse myelitis, and others have been associated. The most common presenting symptom in a patient with Charcot spine is low back pain. Other signs and symptoms include spinal deformity, sitting imbalance, and an audible and/or palpable “clunk,” especially during movement. Other findings may include those of autonomic dysreflexia, such as headache, hypertension, and sweating. Signs and symptoms of autonomic dysreflexia tend to occur in patients with a spinal cord lesion above the T6 level.

Spinal Infection

Infections of the spine are relatively rare compared with other spine pathology but have been increasing in incidence in recent decades. Spinal infections account for approximately 2% to 7% of all orthopedic infections. In developed countries, the incidence of spinal infections ranges from 1:100,000 to 1:250,000. Spinal infections can be caused by a variety of infectious organisms, including bacteria, fungi, mycobacteria, and parasites ( Table 66.3 ). In general, bacterial spine infections are the most common; however, regional variations exist. For example, in countries where tuberculosis remains endemic, tubercular spine infection will be more common. When an infection occurs, it is typically described by its anatomic location. The more common locations are the disc space (discitis), vertebral body (osteomyelitis), and epidural space (spinal epidural abscess [SEA]). When osteomyelitis and discitis are present, the term pyogenic spondylodiscitis is also used. Isolated disc space infection is more common in children because of intervertebral disc vascularity. Zygapophyseal joint, paraspinal soft tissue, subdural, and subarachnoid infections can occur but are much less common. With respect to spinal levels, lumbar is the most common, followed by thoracic, then cervical. Spinal infections are thought to occur from one of three mechanisms. The most common is hematogenous spread from an infection elsewhere in the body. The other sources include spread of an infection from an adjacent infected structure and direct inoculation during a spine-related procedure. A delay in diagnosis of a spinal infection has been shown to increase morbidity and mortality.

Spondylodiscitis

Spondylodiscitis refers to an infection in the vertebral body and disc space, and is the most common infection seen in the spine. There are risk factors and comorbidities that predispose to pyogenic spondylodiscitis. Those conditions that increase the risk include older age, diabetes, immunocompromised states, end-stage renal disease, liver disease, alcoholism, obesity, recent invasive spine procedures, and intravenous drug abuse.

The patient with pyogenic spondylodiscitis can present with a variety of symptoms and/or signs. Some 90% of patients will present with an insidious 1- to 2-month onset of neck or back pain. A low-grade fever may be present in approximately 65% of patients with a pyogenic spondylodiscitis, and only 5% to 30% will present with a neurological deficit. Sepsis may be the initial presentation of a spine infection, which makes the diagnosis more difficult. A thorough review of symptoms and risk factors can help to consider a spine infection in the differential diagnosis.

Physical examination in the patient with pyogenic spondylodiscitis may demonstrate paraspinal muscle spasm and tenderness to palpation. Neurological examination may reveal deficits in a dermatomal and/or myotomal distribution. Cord compression could present with upper motor neuron findings below the level of the lesion. Examination outside of the musculoskeletal and neurological systems is important to identify potential sources of a spinal infection. Examples include infected skin lesions in the patient with psoriasis or infected heart valves (endocartitis) in the patient with a history of intravenous drug use.

Spinal Epidural Abscess

SEA is a relatively rare occurrence, but its incidence has been increasing in recent years. The increase in incidence is thought to be related to an aging population, an increase in intravenous drug use, and a growing number of people with predisposing risk factors such as diabetes mellitus, obesity, end-stage renal disease, and other immunocompromised conditions. ^, A thorough history helps identify those at risk for a spinal infection. SEA is primarily an adult disease, but can occur in the pediatric population. The peak incidence occurs in patients aged 50 to 70 years, with the exception being intravenous drug users, who are typically younger. SEA is typically caused by a bacterial infection, with Staphylococcus aureus accounting for 60% to 70% of cases. Cases of SEA with methicillin-resistant S. aureus have been shown to have an especially poor prognosis. With respect to location, SEAs are most commonly found in the thoracic spine (50%), followed by the lumbar spine (35%) and cervical spine (15%).

The most common presenting symptom in the patient with an SEA is back pain. In fact, 85% of patients with an SEA have back/neck pain upon presentation, followed by fever in about 65% and parasthesias in 40%. The classic triad of back pain, fever, and progressive neurologic deficits occurs in only 10% to 15% of patients with an SEA. Patients with an SEA may describe this episode as the worst back pain they have ever had. The spectrum of physical examination findings may range from paraspinal muscle spasms and tenderness to quadriplegia/paraplegia. For the spine practitioner, a thorough musculoskeletal and neurological examination is essential. Additional physical examination is based on patient history, risk factors, and the urgency of the situation. An SEA has the potential to progress rapidly and cause significant morbidity and mortality. Early diagnosis and treatment has been shown to lead to improved outcomes.

Neoplastic Disease

Spinal neoplastic disease is always in the differential diagnosis when a patient presents with neck or back pain and/or neurological symptoms of myelopathy or radiculopathy. The worldwide incidence of cancer is increasing, in part because of an aging population and advanced imaging technology. Nearly 95% of cancer in the spine is metastatic, whereas only approximately 5% of spine tumors are primary spinal column/spinal cord tumors ( Table 66.4 ). Metastatic disease to the bone is common and ranks third behind metastases to the lung and liver. Approximately 40% of patients with cancer will develop spinal metastases, and about 14% will develop symptomatic spinal metastatic disease. With the increase in early detection of cancer, as well as improved medical oncology and radiation oncology treatment options, patient survival continues to improve. This will likely lead to an increase in patients presenting with spinal metastatic disease, and therefore a need for spine specialists to consider neoplastic disease in the differential diagnosis during their evaluation of any patient.

As with evaluation of any spine patient, the history and review of symptoms is important. A past medical history of cancer in the patient, no matter how remote, is important to know, as some patients thought to be in remission or “cured” of their cancer can have recurrence years later. The patient’s first recurrence may be in the form of spinal metastatic disease. Seventy-five percent of cases of metastatic spine disease comes from cancer of the breast, lung, prostate, thyroid, or kidney, or from multiple myeloma. Intramedullary spinal cord tumors present with a higher incidence of neurological symptoms/signs than the other spine tumors. The highest incidence of spinal metastatic disease is in those 40 to 65 years of age. Also, a family history of cancer is critical, as there are inherited traits predisposing to certain types of cancer. Asking about family members’ history of cancer, including siblings, parents, aunts/uncles, and grandparents, is useful. Obtaining a history of any patient exposure to known carcinogens may help in developing a differential diagnosis.

Patients with primary spinal tumors or spine metastases may initially be asymptomatic. As symptoms develop, they can be quite varied and can mimic more common degenerative conditions. Symptoms may include axial spine pain and can be slowly progressive and diffuse over months or even years, or can be abrupt and severe as in the case of a pathological spinal fracture. The patient with metastatic spine disease may also present with symptoms associated with spinal cord or nerve root compression. Pain is the initial complaint in 85% of patients with a spinal tumor. There may also be symptoms related to the primary organ that is the source of the metastases. Constitutional symptoms may be present, including fever, malaise, and unintended weight loss. Nocturnal spine pain or pain that wakes the patient from sleep, and increased pain with a recumbent position are concerning for destructive lesions of the spine, such as neoplastic disease and infection.

Patients with spinal tumors may, however, have a normal examination. As with any spine patient, the examination includes a neurological and musculoskeletal examination. Additional physical examination maneuvers may be helpful, including palpation of the thyroid gland, abdomen and neck, axilla, and groin for adenopathy. Patients with neck or back pain from a tumor may have focal tenderness to palpation, local muscle spasm, or pain with percussion over the involved area. In the case of spinal cord or nerve root compression, the examination may demonstrate associated upper motor neuron or lower motor neuron findings. When the craniocervical junction is involved, additional findings may include neck and face dysesthesias and weakness of the hands, more so than the lower extremities. Signs and symptoms may also include dysphagia, nausea, vomiting, lower cranial nerve deficits, and respiratory difficulty because of the proximity of the upper cervical cord and the brainstem. These patients may describe numbness in a “cape” distribution. Because of the course of the sympathetic chain, lesions at the craniocervical and cervicothoracic junctions can produce an ipsilateral Horner syndrome. When a thoracic cord lesion is present, one can expect paraparesis, spastic gait, hyperactive lower extremity reflexes (normal upper extremity reflexes), sustained or multibeat clonus, and possible bowel/bladder dysfunction. If the lumbar spine is involved, findings may include weakness, radiculopathy, bladder retention, bowel incontinence, and saddle anesthesia.

Inflammatory Disease of the Spine

Inflammatory spondyloarthropathy is a term used to describe several inflammatory conditions that can have clinical manifestations that involve the spine. These conditions include rheumatoid arthritis (RA) and the seronegative spondyloarthropathies ( Box 66.3 ). The spine-related presenting signs and symptoms in a patient with an inflammatory spondyloarthropathy can be quite varied. This section will review the more common conditions of RA and ankylosing spondylitis (AS).

Rheumatoid Arthritis

RA is a chronic, systemic, inflammatory autoimmune joint disease that affects about 0.5% to 1% of the population. Females are approximately two to three times more affected than males. The incidence of clinically significant RA peaks in the sixth decade. It affects the synovial-lined diarthrodial joints of the spine and limbs, particularly the craniocervical spine and the hands and feet (which typically exhibit symmetric involvement). The pathophysiology of RA is related to an autoimmune, chronic inflammatory process of the synovium and neighboring structures.

With respect to the spine, the upper cervical spine is primarily involved. This is partly related to the abundant amount of synovial tissue in the occiput-C1 and C1‒C2 articulations. The subaxial spine can also be involved, including degenerative facet arthropathy and subsequent spondylolisthesis. In patients with RA, involvement of the cervical spine can be asymptomatic or present with severe neck pain, deformity, and neurological signs and symptoms. Neck pain is the most common presenting symptom and may be accompanied by occipital headaches and face, ear, and upper neck pain because of either local referred pain and/or irritation/compression of the C2 nerve root. In addition, the patient may present with a multitude of neurological signs and symptoms. The destructive changes that accompany RA can result in cranial settling and atlantoaxial and subaxial subluxation. This results in craniocervical instability and associated neurological signs and symptoms. These destructive changes at the craniocervical junction can lead to vertebrobasilar insufficiency and associated symptoms such as vertigo, dysphagia, and nausea/vomiting. Brainstem and upper cord compression may also present with lower cranial nerve dysfunction and upper motor neuron signs/symptoms. Presentation may also include cervical spine deformity and painful cervical spine ROM.

Ankylosing Spondylitis

AS is a chronic inflammatory condition that primarily affects the axial skeleton, but large peripheral joints may also become involved. AS occurs in approximately 0.2% of the Caucasian population. There is a strong relationship between human leukocyte antigen B27 positivity and AS; however, other genetic and environmental factors play a role in the development and progression of this disease. Males are more frequently affected than females (3:1), and the average age of onset is 26 years. AS typically begins with a sacroiliitis, followed by progressive ossification of the annulus, anterior longitudinal ligament, zygapophyseal joints, ligamentum flavum, and interspinal ligaments. Ossification tends to progress from caudal to cranial, eventually resulting in ankylosis of nearly the entire spinal column. Unfortunately, a delay in diagnosis for many years is not uncommon owing to the insidious nature of symptom progression.

Clinical presentation typically begins with an insidious onset of low back pain, likely related to the early hallmark sign of sacroiliitis. Chronic low back pain without other signs or symptoms often leads to a delay in diagnosis. As the disease process advances, it includes decreasing spine ROM, morning stiffness, and progressive flexion deformity. Extraarticular manifestations in the patient with AS include ophthalmological, pulmonary, neurological, and cardiac conditions. In fact, pulmonary function declines, and chest expansion becomes limited because of rigidity/ankylosis of the thoracic cage. Additionally, cardiac conduction abnormalities can occur in patients with spondyloarthropathies such as AS. In the patient with known AS, an onset of new back pain, even with relatively minor trauma such as a ground level fall, may indicate the presence of a fracture, and the spine should be considered potentially unstable until proven otherwise. Plain radiographs are not adequate in this patient population if performed in the recumbent position, as the spinal column may appear well-aligned. Computed tomography (CT) and/or magnetic resonance imaging (MRI) are often required to make the diagnosis.

Vascular Lesions Affecting the Spinal Cord