Case Presentation: A 61 year old female presented to the ED with rapidly progressing lower extremity weakness, gait abnormalities, and urinary incontinence. Her neurologic exam was pertinent for bilateral lower extremity motor deficits, diminished reflexes, and weakened rectal tone. MRI spine without contrast showed no cord compression prompting further evaluation with LP. CSF showed elevated protein of 55 with normal cell count leading to concern for an acute inflammatory demyelinating polyradiculoneuropathy (AIDP), for which IVIG was started. Further MRI spine imaging with contrast showed hyperintensity in the distal thoracic cord. The patient was started on high dose methylprednisolone with slightly improved neurological exam findings. Given some clinical improvement with pulse dose steroids and her new MRI findings, the patient was diagnosed with acute transverse myelitis (ATM). Steroids were continued with initiation of plasmapheresis, resulting in further improvement. Additional investigation for the etiology of ATM revealed an elevated SSA antibody.
Discussion: Acute transverse myelitis (ATM) is a spinal cord disorder often causing rapidly developing motor, sensory, and autonomic deficits. It is a rare disorder with annual incidence rates of 1 to 8 per 1 million people; however, this rate is likely an underestimation due to difficulties in establishing a definitive diagnosis. Common features of ATM include radiating extremity pain, paresthesias, muscle weakness, and urinary incontinence. Other diagnoses to consider due to overlapping clinical features are AIDP, multiple sclerosis, neuromyelitis optica spectrum disorders, cord compression, and cord ischemia. Typical diagnostic findings include signal enhancement at the affected cord level on MRI and CSF analysis significant for lymphocytosis or elevated protein. If ATM is suspected, high-dose IV steroids should be initiated urgently. Further maintenance treatment options include plasmapheresis and even immunosuppressive agents in severe cases. Etiologies of ATM include a precipitating infectious insult, a predisposing autoimmune/inflammatory condition, or idiopathic by nature. To determine the true etiology an extensive laboratory workup must be performed. Our patient had an elevated SSA antibody despite having no systemic features of a connective tissue disorder. There are case reports that describe an association between elevated SSA levels and the development of ATM. This association is important in regards to the disease pattern of ATM, as elevated SSA levels were found to correlate with higher rates of recurrence of ATM after initial treatment with pulse dose steroids. It has been postulated that a subclinical presentation of mixed connective tissue disorders may be a trigger for ATM due to the autoimmune nature of the disease. Several sources even recommend considering long term immunosuppressive therapy in these cases to prevent recurrence.
Conclusions: Hospitalists should have a high index of suspicion and low threshold for aggressive treatment of ATM due to its rapidly progressive features. This case serves to raise awareness to the possible autoimmune nature of ATM, as findings such as elevated SSA levels may have prognostic and treatment implications. Due to these implications it is imperative to perform a thorough autoimmune workup on initial presentation.