Transverse myelitis is an inflammatory disorder that presents with acute or subacute spinal cord dysfunction resulting in weakness, sensory alterations, and autonomic impairment (eg, bowel, bladder, and sexual dysfunction) below the level of the lesion. Idiopathic TM is defined by its occurrence without a definitive etiology despite a thorough work-up. Secondary (disease-associated) TM is most often related to a systemic inflammatory autoimmune condition.
Subtypes of TM are differentiated on the basis of the clinical severity and radiologic extent of the spinal cord lesion. These include acute partial TM, acute complete TM and longitudinally extensive TM (LETM).
●Acute partial TM refers to spinal cord dysfunction that is mild or grossly asymmetric with an MRI lesion extending one to two vertebral segments.
●Acute complete TM refers to spinal cord dysfunction that causes symmetric, complete or near complete neurologic deficits (paresis, sensory loss, and autonomic dysfunction) below the level of the lesion with an MRI lesion extending one to two vertebral segments.
●Longitudinally extensive transverse myelitis (LETM) refers to complete or incomplete spinal cord dysfunction with a lesion on MRI that extends three or more vertebral segments.
These subtypes of TM, while imperfect, imply distinct differential diagnoses and prognoses.
The diagnosis of TM is suspected when there are acute or subacute signs and symptoms of motor, sensory, and/or autonomic dysfunction that localize to one or more contiguous spinal cord segments in patients with no evidence of a compressive cord lesion. Thus, the diagnosis of TM requires exclusion of a compressive cord lesion, usually by MRI, and confirmation of inflammation by either gadolinium-enhanced MRI or lumbar puncture.
Diagnostic criteria — Diagnostic criteria for TM include the following requirement
●Sensory, motor, or autonomic dysfunction attributable to the spinal cord
●Bilateral signs and/or symptoms
●Clearly defined sensory level
●No evidence of compressive cord lesion
●Inflammation defined by cerebrospinal fluid pleocytosis, elevated IgG index, or gadolinium enhancement on MRI
●Progression to nadir between 4 hours and 21 days
These criteria are useful for defining populations for clinical trials, but some patients presenting with TM may not fulfill all of the above criteria. As an example, a significant percentage of individuals with a clinical pattern that otherwise resembles TM do not meet the inflammatory features; therefore, the absence of inflammatory markers does not rule out TM .
Investigations — The following investigations are recommended for the evaluation of all patients with suspected TM .
●MRI of the entire spine, with and without gadolinium, to evaluate for compressive versus noncompressive cord lesion(s)
●Brain MRI with and without gadolinium to evaluate for the presence of brain lesions suggestive of multiple sclerosis
●Cerebrospinal fluid analysis including cell count and differential, protein, glucose, VDRL, oligoclonal bands, immunoglobulin G index, and cytology
●Serum NMO-IgG antibodies (anti-aquaporin-4 IgG), serum B12, methylmalonic acid, human immunodeficiency antibodies, syphilis serologies, serum ANA, Ro/SSA, and La/SSB antibodies, and thyroid stimulating hormone
For patients with longitudinally extensive spinal cord lesions, the following tests are additionally recommended .
●Serum erythrocyte sedimentation rate, C reactive protein, antinuclear antibodies, antibodies to extractable nuclear antigen, rheumatoid factor, antiphospholipid antibodies, and antineutrophil cytoplasmic antibodies
●Chest CT to evaluate for evidence of sarcoidosis
Select patients may need additional testing .
●Infectious serologies and cerebrospinal fluid studies
●Serum copper and ceruloplasmin
●Serum vitamin E level
●Electrodiagnostic evaluation (somatosensory evoked potentials, nerve conduction studies, electromyography)
●Salivary gland biopsy
Intravenous glucocorticoids have long been considered the standard of care and first-line therapy in acute idiopathic TM. Even without placebo-controlled trials evaluating glucocorticoids specifically in TM is good evidence that intravenous glucocorticoids are effective in acute inflammatory central nervous system diseases like TM, such as multiple sclerosis.
Preferred regimens are **methylprednisolone (1000 mg daily) or dexamethasone (200 mg daily) for three to five days. **Continued treatment with glucocorticoids or more aggressive regimens is based upon the clinical course and radiologic parameters.
Plasma exchange may be effective for acute central nervous system demyelinating diseases that fail to respond to high-dose glucocorticoid treatment . Thus, in addition to high-dose glucocorticoid therapy, we suggest treatment with plasma exchange for patients who have acute TM with motor impairment .Our preferred regimen is five treatments, each with exchanges of 1.1 to 1.5 plasma volumes, every other day for 10 days For patients with significant deficits, waiting until glucocorticoid treatments are completed is not necessary. Clinical judgment must be used and some patients may benefit from each .
Most patients with idiopathic TM have at least a partial recovery, which usually begins within one to three months and continues with exercise and rehabilitation therapy. Some degree of persistent disability is common, occurring in about 40 percent. A very rapid onset with complete paraplegia and spinal shock has been associated with poorer outcomes. Recovery can proceed over years.
●The majority of patients with TM experience monophasic disease. Recurrence has been reported in approximately 25 to 33 percent of patients with idiopathic TM. With disease-associated (secondary) TM, the recurrence rate may be as high as 70 percent.
●Patients presenting with acute complete transverse myelitis have a generally cited risk of multiple sclerosis of only 5 to 10 percent. However, patients with partial myelitis as an initial presentation and cranial MRI abnormalities showing lesions typical for multiple sclerosis have a transition rate to multiple sclerosis over three to five years of 60 to 90 percent. In contrast, patients with acute partial myelitis who have a normal brain MRI develop multiple sclerosis at a rate of only 10 to 30 percent over a similar time period
DR Atul Chowdhury
MD GENERAL MEDICINE