Transverse Myelitis

Introduction - Acute transverse myelitis is a spinal cord disorder that may present with the rapid onset of weakness, sensory alterations, and bowel or bladder dysfunction. TM can occur as an independent entity, most often a postinfectious complication, but TM may occur along with neuro-inflammatory disorders such as acute disseminated encephalomyelitis, multiple sclerosis, and neuromyelitis optica. It is important in the evaluation of patients with acute myelopathies to exclude compressive and noninflammatory causes of myelopathy because the treatment options will vary depending on the etiology. Compressive etiology may require urgent neurosurgery!

Differentiating TM from acute inflammatory demyelinating polyneuropathy (AIDP) - Patients with acute inflammatory demyelinating polyneuropathy (AIDP, Guillain-Barre syndrome) may also present with progressive sensory and motor dysfunction. There are several features that may be used to rapidly discriminate patients with AIDP from those with acute myelopathies.

• Patients who have AIDP often have both upper and lower extremity involvement. In contrast, patients with myelopathy will have dysfunction that is specific to the level of myelopathy. 
• Patients with myelopathy are more likely to have urinary or bowel urgency or retention, while those with AIDP are more likely to have cardiovascular instability. 
• A sensory level is often definable in patients with acute myelopathy but is never present in AIDP. 
• Cerebrospinal fluid analysis in AIDP usually shows an elevated protein with few white cells (this is known as cyto-albuminologic dissociation) whereas patients with TM may have an inflammatory cerebrospinal fluid with an elevated number of white blood cells and IgG index. 
• Spinal MRI imaging often shows a discrete lesion in myelopathy, whereas spinal MRI is normal in AIDP. 
• Electrodiagnostic studies may show conduction block or slowed conduction of peripheral nerves in AIDP and are usually normal in myelopathies.

Etiology

In 30 to 60 percent of the idiopathic TM cases, there is an antecedent respiratory, gastrointestinal, or systemic illness. In parainfectious TM, the injury may be associated with direct microbial infection of the central nervous system, or with the systemic response to infection by a variety of agents such as varicella zoster virus, herpes virus, and Listeria. TM may be associated with central nervous system vasculitis or infarction/ischemia of the spinal cord.  Alternatively, TM can be directly associated with infectious, systemic inflammatory, or multifocal central nervous system disease.

Although idiopathic TM usually occurs as a postinfectious complication that appears to result from an autoimmune process, TM can be directly associated with infectious, systemic inflammatory, or multifocal central nervous system disease.
Acquired central nervous system autoimmune disorders that can cause TM include multiple sclerosis, neuromyelitis optica, and acute disseminated encephalomyelitis.

• Multiple Sclerosis - TM can occur as part of the spectrum of multiple sclerosis. 
• Neuromyelitis Optica - TM manifesting as a longitudinally extensive spinal cord lesion spanning three or more vertebral segments is one of the characteristic findings of neuromyelitis optica. NMO antibodies may be ordered if this is suspected. 
• Disseminated Encephalomyelitis - TM may be seen in patients with acute disseminated encephalomyelitis, a demyelinating disease of the central nervous system.

Other central nervous system conditions that can cause TM are as follows:
- Infections including but not limited to West Nile virus, herpes viruses, HIV, HTLV-1, Lyme, Mycoplasma, Syphilis, Paraneoplastic syndromes and Neurosarcoidosis

 Systemic inflammatory autoimmune disorders that are associated with TM include the following:
-Ankylosing spondylitis
-Antiphospholipid antibody syndrome
-Behcet disease
-Mixed connective tissue disease
-Rheumatoid arthritis
-Scleroderma
-Sjogren syndrome
-Systemic lupus erythematosus

CLINICAL FEATURES — The onset of TM is characterized by motor, sensory and/or autonomic dysfunction (bowel, bladder, and sexual dysfunction). Motor symptoms include a rapidly progressing paraparesis with initial flaccidity followed by spasticity. The patient may describe sensory symptoms such as pain, dysesthesia, and paresthesia. Autonomic symptoms include increased urinary urgency, bladder and bowel incontinence, difficulty or inability to void, constipation, and sexual dysfunction.

MRI of the spinal cord typically shows a gadolinium-enhancing signal abnormality (seen in the image below), usually extending over one or more cord segments. The cord often appears swollen at the affected levels.



-Cerebrospinal fluid (CSF) is abnormal in approximately one-half of patients, with a moderate lymphocytosis and an elevated protein level

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
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 or elevated IgG index or gadolinium enhancement



Treatment
Steroids
IVIG
Plasmapharesis