Differential Diagnosis for Cervical Spondylotic Myelopathy

Cervical spondylotic myelopathy (CSM) is diagnosed clinically, taking into account the patient’s medical history, the presence of abnormal findings during a physical examination, and imaging studies that provide confirmation.

In some cases, the diagnosis of cervical spondylotic myelopathy (CSM) can be unequivocally confirmed through the patient’s medical history, physical examination, and imaging studies, while in other instances, the presentation may be less straightforward. CSM can be mimicked by various neurological disorders that present with similar symptoms.

Intracranial, demyelinating, motor neuron, infectious, inflammatory, and metabolic abnormalities are some of the underlying causes of neurological conditions that can resemble CSM.

Identifying CSM is crucial to minimize the risk of delayed diagnosis and permanent disability resulting from progressive neurological decline. CSM typically has an insidious onset and tends to advance gradually in a stepwise pattern.

Primary Diagnostic Features of CSM

While the diagnosis of GSM relies on medical history, physical examination, and imaging results, some patients may not exhibit any symptoms, while others may only have mild neck or arm pain.

Numbness or clumsiness in the hands, difficulties with walking, stiffness in the neck and legs, and sensory disturbances in the arms or legs are among the most frequent symptoms of GSM. Additional indications of GSM encompass muscle atrophy in the hands, a positive Hoffman or Babinski reflex, motor impairments, hyper-reflexia, an unsteady gait with a wide base, as well as issues with bowel and bladder control.

Diagnostic imaging plays a crucial role in identifying and verifying GSM, and in providing a visualization of the degree of compression on the spinal cord. Following plain radiographs, Magnetic Resonance Imaging (MRI) is usually employed as the initial imaging modality as it can assess the dimensions of the spinal canal and vertebrae, the severity of degenerative changes such as spondylosis, the degree of compression on the spinal cord, and any structural abnormalities.

The diverse range of signs and symptoms associated with GSM and their varying degrees of severity can make it challenging to differentiate from other conditions.

Hence, it is critical to recognize the distinctive features of GSM by considering factors such as patient demographics, findings from physical examination, MRI and other imaging tests, as well as relevant medical history.

Congenital or Anatomic Conditions

Hypoplasia of the atlas and congenital cervical stenosis are among the congenital anomalies that have been identified as potential causes of myelopathy. When lateral radiographs suggest the possibility of congenital anomalies, MRI or computed tomography must be utilized to verify the diagnosis and gain a more precise understanding of the anatomical structures involved.

Myelomalacia in patients can be visualized through MRI images, which may show areas of hyperintensity on T2-weighted and hypointensity on T1-weighted images of the spinal cord.

Degenerative

The literature has reported atypical degenerative conditions as a potential cause of progressive cervical myelopathic symptoms. The diagnosis of retro-odontoid disc herniation can be established through MRI, which shows a soft-tissue mass compressing the medulla and upper cervical cord from the posterior aspect.

Contrast-enhanced MRI can be an effective method for identifying the location of synovial cysts. Specifically, an enhanced extradural lesion can be observed located posteriorly to the cord and in close proximity to a facet joint, resulting in anterior displacement of the cord. These diagnoses can be confirmed through tissue examination.

Neoplastic Diagnoses

Even though some MRI results may be uncommon for CSM, a histological assessment is necessary to confirm the diagnosis. Multilevel degeneration leading to severe compression of the spinal cord can result in an initial diagnosis of CSM, which may prompt bilateral laminectomy.

Subsequent MRI follow-ups may reveal T2 hyperintensities and persistent contrast enhancement at the C3-C4 level, which are believed to be associated with the progression of myelopathy at the gliosis stage. Insight into the differential diagnosis relative to CSM can be obtained by considering the patient’s age and prior medical history.

A case study in the literature described a patient who was 23 years old and had a medical history of quadriparesis caused by infectious myelitis at age 13 and left greater trochanter osteochondroma surgery at age 15. The patient experienced severe neurological decline, and a cervical MRI showed a 22 mm mass that narrowed the spinal canal to 3 mm, compressed the cord, and had an associated 10 mm syrinx.

The mass was excised and biopsied, revealing osteochondroma without abnormalities but suggesting malignant transformation. Based on this patient’s age and medical history, a diagnosis of CSM may not be appropriate.

Inflammatory or Autoimmune Diagnoses

Pseudogout in the odontoid region can be detected using MRI, where it may appear as non enhanced and isointense to neural tissue on T1-weighted images, and as heterogeneous and hyperintense on T2-weighted images. Furthermore, the use of gadolinium may reveal peripheral enhancement.

The literature has documented cases of spinal sarcoidosis that imitates cervical spondylotic myelopathy (CSM), where a clearly defined high signal intensity region can be observed within the spinal cord on T2-weighted magnetic resonance images.

Idiopathic Diagnose

The literature has also reported on idiopathic disease processes that can imitate cervical spondylotic myelopathy (CSM). Different electrophysiological techniques have been examined to differentiate amyotrophic lateral sclerosis (ALS) from cervical spondylotic myelopathy (CSM).

One of the techniques involves measuring motor-evoked potentials (MEP) from the trapezius muscle. In all cases of amyotrophic lateral sclerosis (ALS), trapezius MEPs show abnormalities, while in patients with cervical spondylotic myelopathy (CSM), they are normal.

Electromyography (EMG) findings can also be used as a technique to distinguish between idiopathic disease processes and cervical spondylotic myelopathy (CSM). EMG findings are present in both the upper and lower limbs in cases of amyotrophic lateral sclerosis (ALS), whereas individuals with ALS-like symptoms resulting from cervical spondylotic myelopathy (CSM) exhibit EMG findings solely in the upper limbs.

The evaluation of sternocleidomastoid muscle EMG (SCM-EMG) and dermatomal somatosensory-evoked potentials has shown that SCM-EMGs are abnormal in individuals with amyotrophic lateral sclerosis (ALS) and normal in those with cervical spondylotic myelopathy (CSM), while dermatomal somatosensory-evoked potentials display the opposite pattern.

Vascular Pathologies

MRI observations of modified vascular anatomy may aid in distinguishing arteriovenous malformations (AVM), arteriovenous fistulas (AV), and other anomalous vasculature from cervical spondylotic myelopathy (CSM). The diagnosis can be confirmed through angiography findings. In cases where necessary, MR angiography can be utilized to confirm the existence of an intradural arteriovenous malformation (AVM).

Metabolic Analyses

To distinguish between intraspinal tumoral calcinosis of the cervical spine and progressive myelopathy, an MRI evaluation is necessary. The MRI may show a posterior extradural mass leading to spinal cord compression, appearing as isointense and heterogeneous on both T1- and T2-weighted images, and exhibiting significant enhancement following the administration of gadolinium.

Tissue analysis may reveal calcium deposits and foreign body giant cells encased in a fibrous capsule, which are indicative features of tumoral calcinosis. When assessing a patient with cervical spondylotic myelopathy (CSM), a comprehensive neurological examination should encompass motor and sensory examinations, reflex evaluations, and the assessment of provocative signs.

The existence of hyper-reflexia and/or provocative signs may suggest the presence of cervical spondylotic myelopathy (CSM). In patients with cervical spondylotic myelopathy (CSM), radiographic assessment typically reveals spinal cord compression with or without signal alterations within the spinal cord.

Cerebrospinal Fluid

Cerebrospinal fluid (CSF) profiles play a crucial role in distinguishing between various neurological conditions. Even though multiple biomarkers and substances have been recognized, the clinical decisions regarding neurological diagnoses are predominantly based on general observations such as pigmentation, leukocyte count, protein concentration, and glucose levels.

When considering conditions affecting the spine and spinal cord, CSF profiles can aid in differentiating neoplastic, vascular, infectious, inflammatory, or degenerative disorders. In the event of the absence of an infection, an increased white blood cell (WBC) count is indicative of an inflammatory or demyelinating disorder. These conditions may comprise systemic lupus erythematosus, Sjogren syndrome, sarcoidosis, neuromyelitis optica, or multiple sclerosis (MS).

Electrodiagnosis

Electrodiagnostic tests such as EMG, electroneurography or NCS, and evoked potentials can assist in distinguishing patients with spondylotic neural compression from those with similar conditions.

Abnormal EMG findings may include absence of insertion activity in various neuromuscular disorders, reduced activity in metabolic disorders, or prolonged activity in denervated muscle. Fasciculation potentials, while sometimes present in normal muscle, can also aid in the diagnosis of patients with chronic partial denervation such as ALS.

Changes in motor unit potentials may also assist in the diagnosis of various diseases. Double discharges at the onset of voluntary contractions may indicate disorders of the anterior horn cells, roots, and peripheral nerves.

Myokymic discharges can reflect radiation myelopathy, MS, chronic radiculopathy, entrapment neuropathy, or syringomyelia. Neuromyotonic discharges may be present in patients with peripheral axonal or demyelinated neuropathy.

NCS provides valuable measurements of motor and sensory conduction velocities in peripheral nerves. Motor and sensory conduction velocities of peripheral nerves can be quantified through NCS, which involves the placement of two electrodes at different points along a peripheral nerve.

The time interval between the stimulus and recorded response is measured, and the result is divided by the distance between the two electrodes. If a patient presents with bilateral sensory complaints in the hands, it is important to consider cervical cord pathology as a potential cause. In such cases, cervical MRI should be performed even if the EMG/NCS indicates bilateral carpal tunnel syndrome.

ALS is a condition that usually manifests in middle age and affects both upper and lower motor neurons. Patients with ALS commonly experience muscular weakness, atrophy, and fasciculations in their limbs, along with muscular spasticity.

ALS can be distinguished from CSM by the lack of sensory changes or pain, the existence of tongue fasciculations, and typical bladder and bowel function. CSF biomarkers, including cystatin C, VGF, and neuroendocrine protein 7B2, have been identified as useful in distinguishing ALS from other neurodegenerative diseases and healthy individuals.

Other biomarkers that may distinguish ALS from other neurodegenerative diseases and healthy individuals include erythropoietin, hepatocyte growth factor, and neurofilament subunits.

Abnormal fluid-filled cavities or cysts that form in the spinal cord are known as syringomyelia.Syringomyelia has an earlier onset of symptoms compared to CSM, but similar to CSM, it develops gradually and advances in an unpredictable manner.

Symptoms of syringomyelia include sensory loss, weakness and atrophy in the upper limb, spasticity in the legs, bladder and bowel dysfunction, and Horner syndrome. Based on the presence of similar symptoms, it is advisable to consider syringomyelia as a potential diagnosis when evaluating for CSM.

One may experience symptoms similar to CSM, such as sensory and motor deficiencies, gait ataxia, absence or severe diminishment of deep tendon reflexes, and presence of pathological reflexes (Babinski sign), due to Vitamin B12 deficiency.

Typically, these symptoms are accompanied by dementia and/or psychiatric symptoms. Patients who present with symptoms of gait ataxia, motor or sensory deficits along with a history of pernicious anemia or GI abnormalities should be suspected of having Vitamin B12 deficiency.

Spinal tumors that compress the cord can cause symptoms similar to CSM. Other diagnoses that should be considered include any condition that can lead to cord compression, such as compressive, non-compressive, and chronic myelopathies.