Approach to acute or subacute myelopathy

Abstract

Improved understanding of the differential diagnosis and improved investigative techniques, particularly neuroimaging and serologic testing, have facilitated the diagnosis of patients with acute and subacute myelopathy and reduced the proportion of patients who are labeled as having “idiopathic transverse myelitis.” Additionally, these advances have identified subgroups of patients in whom progression of deficit or future relapses are anticipated, allowing intervention and prophylaxis as appropriate. However, early management remains empiric and consists of high-dose corticosteroids for most patients. In the event of an inadequate response to corticosteroids or a subsequent atypical course, further investigations to detect diagnoses other than “transverse myelitis” should be considered and additional treatments, such as plasmapheresis, may be appropriate. Individualized diagnosis and treatment is more feasible now than in the past. Localizing an acute neurologic process to the spinal cord is often, but not always, straightforward (table 1). The ascending sensory symptoms of acute inflammatory demyelinating polyradiculoneuropathy (AIDP) may confuse the diagnosis, as this complaint is also highly associated with acute myelopathy. Unequivocal upper motor neuron signs exclude AIDP, but are often not apparent in the early stages of a spinal cord insult. Although not invariably present, an unequivocal sensory level on the torso, sensory loss indicating involvement of spinal tracts (e.g., spinothalamic modality impairment contralateral to motor findings), or urinary retention localize to the spinal cord. Myopathy or neuromuscular junction disorders may be mistaken for myelopathy, particularly if the lower limbs are predominantly affected, but the absence of any sensory abnormality should suggest the correct localization. Bilateral mesial frontal lobe lesions (e.g., bilateral anterior cerebral artery distribution infarcts) could mimic a myelopathy, although abulia or other signs of frontal lobe dysfunction typically coexist. Autoimmune or paraneoplastic muscle stiffness syndromes, such as stiff-person syndrome associated with glutamic acid decarboxylase or amphiphysin autoantibodies, may be confused with spasticity …