Mycoplasma pneumoniaeassociated transverse myelitis presenting as asymmetric flaccid paralysis

Salloum, Shafee; Goenka, Ajay; Ey, Elizabeth

Acute transverse myelitis (ATM) is an immune-mediated spinal cord disorder which presents with acute onset of motor, sensory, and autonomic dysfunction. About 20% of ATM cases occur in children with an annual incidence of two cases per million. 1,2 A bimodal age distribution is noticed in children younger than 5 years and children older than 10 years. 2 Compared to adults, pediatric ATM is more frequently postinfectious, thoracic, longitudinally extensive, and has a better outcome. 3 The most common causes of ATM are presented in Table 1 . 3 It is important to recognize that the nadir of symptoms in ATM is between 4 hours and 3 weeks. Rapid progression of symptoms in less than 4 hours indicates an ischemic event while progression of symptoms beyond 3 weeks is more consistent with chronic hereditary myelopathy. 1, 3 Pain is the most common initial symptom. Other symptoms include motor deficits and weakness which occasionally can be unilateral as we noticed in this case. Patients may develop initial flaccid motor weakness and hyporeflexia similar to this case. This is usually due to initial spinal shock which results in lower motor neuron signs. 1-3 Sensory symptoms include positive symptoms such burning sensation or negative symptoms such numbness. Patients usually have sensory loss in a band-like or transverse level (and here is the name transverse myelitis). Autonomic symptoms are virtually seen in all patients with ATM. These might include urinary retention and constipation. 1-3 MRI spine is an essential tool in the diagnosis. It helps exclude extrinsic compression lesions like tumors or arteriovenous malformation. MRI spine in ATM shows centrally located lesions with high T2 signal intensity involving grey matter and neighboring white matter. Longitudinally extensive transverse Case Report myelitis (LETM), which is defined as involvement of ≥3 vertebral segments, occurs in 66-85% of ATM in children. 2 Brain MRI is expected to be normal in ATM. However; asymptomatic lesions are seen in more than 40% of children with ATM indicating the need to include brain MRI in evaluation for ATM. 2 Neurological complications occur in 0.1% of patients with M. pneumoniae infections, and among these, encephalitis is the most commonly encountered one. It is estimated that 5-10% of childhood encephalitis cases are attributed to M. pneumoniae infection. 3, 4 M. pneumoniae-associated ATM usually involves the thoracic spinal cord and arises 2-4 weeks after antecedent respiratory infection. 3, 5 This is in contrast to our patient who developed neurological symptoms within one week of his respiratory illness and his MRI showed mainly cervical spinal cord involvement.