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Neck pain disguised as spondyloarthrosis
Q1: What is the differential diagnosis?
Spondyloarthrosis is the most common condition presenting as neck pain, although it usually appears as an incidental finding in older asymptomatic subjects in cervical radiographs. In fact, myelopathy develops in only 5%–10% of the symptomatic patients,1 although spondylosis is the most frequent cause of medullary disease in subjects older than 50 years.2 Osteophyte formation enhances stability between adjacent vertebral bodies in the elderly. The greater mobility of intervertebral junctions due to aged discs and the decreased ability of vertebral body endplates to bear weight trigger spur formation. If osteophytes progress posteriorly or posterolaterally, the patient might eventually develop compression of the neural foramen and the spinal canal.
In our case, the initial suspicion of spondyloarthrosis was confirmed by regular radiography. The patient was on no medication other than non-steroidal anti-inflammatories, and there was no medullary exposure to radiation. No previous trauma was reported, and radiography ruled out the possibility of fractures or subluxation. Nevertheless, over a one year period new clinical data pointed towards other entities as potential diagnostic options.
Chronic epidural abscess may progress insidiously, mimicking an extrinsic spinal cord neoplasm. This entity could not be ruled out by a normal erythrocyte sedimentation rate (ESR) and the absence of fever, because both might be missing in chronic processes or immunosuppressed subjects. Therefore neuroimaging is indicated to discount epidural collections, particularly if there is a history of diabetes, back trauma, or immunosuppression.
Spinal tuberculosis could also progress slowly and the patient have a normal ESR; MRI ruled out this diagnosis in our case.
Metabolic diseases, such as diabetes mellitus or Paget’s disease, were ruled out by the normal results reported for blood tests and radiography.
Demyelinating diseases like multiple sclerosis would not explain the exploratory findings. There were no symptoms such as concomitant focal deficits, transverse myelitis, or optic nerve disease that could suggest demyelination. Neither amyotrophy nor fasciculations were observed, thus a diagnosis of lateral amyotrophic sclerosis could be reasonably discarded.
The appearance of left C5 irradiated pain, and the association of increasing weakness of the ipsilateral upper limb, suggested root compression. The addition of spasticity, urge mictional incontinence, and ultimately tetraparesis indicated spinal compression. The rapid worsening of the former symptoms (months instead of years) suggested a non-spondylotic cause, and thus raised the possibility of neoplastic involvement.
Neuroimaging should be used if there are congenital problems and any conditions involving degenerative skeletal or spinal structures, besides those entities that can be dismissed by regular neck radiography. MRI allows the examination of spinal cord, nerve roots, subarachnoid space, soft tissue anomalies, and is also preferred for the study of intradural or extradural neoplastic growths.
Medullary vascular malformations such as strawberry angiomas or arteriovenous fistulas are other rare known causes of medullary compression. Chronic manifestations producing a mass effect may also be considered in differential diagnosis.
Box 1 shows the different entities responsible for cervical myelopathy and radiculopathy.
Box 1: Differential diagnosis of cervical myelopathy and radiculopathy
Spinal or skeletal: discogenic disease, spondylosis or soft disc, ligamentum flavum hypertrophy, ossification of the posterior longitudinal ligament, frozen shoulder, facet arthropathy, shoulder impingement syndrome.
Neurological: amyotrophic lateral sclerosis.
Intramedullary: glioma, haemangioblastoma, metastatic.
Extramedullary: schwannoma, neurofibroma, meningioma.
Extradural: schwannoma, neurofibroma, meningioma, metastatic.
Brachial plexus: Pancoast’s tumour, schwannoma, neurofibroma.
Fractures, subluxation, root avulsion, stretch injury.
Vasculitis, ankylosing spondylitis, polymyositis, polymyalgia rheumatica, rheumatoid arthritis.
Epidural abscess, vertebral osteomyelitis, Pott’s disease, discitis, vertebral osteomyelitis, herpes zoster.
Diabetes, Paget’s disease, porphyria, pernicious anaemia.
Arteriovenous malformations, dural arteriovenous fistulas, carvernous angiomas, capillary telangiectasias.
Syringomyelia, os odontoideum, Arnold-Chiari malformation, platybasia, tethered cord syndrome.
Q2: What is the diagnosis?
Extramedullary schwannoma accounts for 30% of primary spinal tumours,3 and also for most clinical pictures involving extramedullary compression.4 Cervical and lumbar sites have been mentioned as the most frequent locations.5 As seen in our case, root pain usually appears as the presenting symptom.
There are two pathological variants, interwoven bundles of long spindle shaped Schwann cells (Antoni A type), often intermingled with areas of more polymorphic Schwann cells embedded in a loose eosinophilic matrix (Antoni B).
Q3: If compression of medullary structures is found, would it be of intramedullary or extramedullary nature?
Clinical presentation of medullary involvement seems to correlate with an intramedullary or extramedullary component. Whereas radicular pain has mostly been associated with early extramedullary compressions, the concurrence of initial first and second motor neurone lesions evokes intramedullary involvement. Physical examination confirmed the former possibility in our patient when a decrement of the left bicipital reflex, that located the deficit at a C4–5 site, was detected. Later on, lower limb spasticity appeared as spinal compression progressed. Further development of the clinical picture showed urge mictional incontinence, and a progressive paresis, with sensitive involvement supported our initial findings.
MRI study shows an extramedullary mass with uniform signal of 2 × 0.8 × 1 cm at posterior and lateral left sites at C4 level (fig 2; see p 119). The medullar bone intensity right over the expansive process is altered, the spine duct shows deformity, and there is oedema. The tumour showed an enhanced signal intensity when endovenous gadolinium contrast was administered. Degenerative changes at C3–C5 level increase duct stenosis. Radiological differential diagnosis of extramedullary contrast enhancing lesions was made and astrocytomas, haemangioblastomas, ependimomas, metastasis, and other possibilities were discounted. The extramedullary neoplastic growth was explained by the pathological evidence of schwannoma.
Q4: What is the treatment and prognosis of this condition?
Surgery should be performed in cases of this nature. The degree of severity before removal correlates with the outcome.5 Prognosis also depends on the possibility of total resection of the mass. If the latter is possible, complete relief or at least stabilisation of symptoms will occur. However, incomplete tumourectomy might be acceptable if surgery jeopardised key neural structures.
Our patient underwent laminectomy at the C3–C4 level, and complete tumourectomy was performed. The postoperative course showed a remarkable improvement in the patient’s motor abilities and sensitivity, and he is still improving his functional performance through rehabilitation.
Schwannomas are benign neoplasms and are typically encapsulated with slow local progression and root or medullary compression. Although some patients show some degree of paresis after surgery, their life expectancy equals that of the general population.
Pain might be a misleading symptom. In fact, neck pain usually relates to cervical spondyloarthrosis in the elderly, although some ominous clinical entities might progress “in disguise” and thus, remain unrecognised. Therefore, all subjects presenting with cervical or irradiated pain (to the chest, back, or abdomen) should undergo a complete neurological examination in order to discount root or medullary compression, even if more frequent conditions (that is, spondyloarthrosis, myocardial infarction, pancreatitis) are suspected.