Progressive Encephalomyelitis with Rigidity and Myoclonus: A pediatric Case Report and Literature Review

Abstract Progressive Encephalomyelitis with Rigidity and Myoclonic (PERM) is a serious life-threatening autoimmune disease characterized by rigidity, muscle pain spasm, deep and shallow sensory impairment, brainstem spinal cord symptoms, autonomic dysfunction, sudden spontaneous, stimulus-induced myoclonus. PERM demonstrates varied initial symptoms and involves the extremities, brainstem, spinal cord, and autonomic nerves. Most cases show significant improvement with immunotherapy. PERM is rarely seen in children. We report an 11-year-old boy with PERM. His presentation began with abdominal pain and skin itching, followed by dysuria and urinary retention, truncal and limb rigidity, spasms of the trunk and limbs during sleeping, deep and shallow sensory disturbances, and dysphagia. Tissue-based assay (TBA) demostrated positive cell-like fluorescence in neuronal dendrites of the hippocampus and cerebellum’s Purkinje cells. He had fluctuating clinical response despite immunotherapy (immunoglobulin, dexamethasone and plasmapheresis). In the fifth month since admission, he showed gradual and persistent clinical improvement after one month of stronger immunotherapy treatment of intravenous immunoglobulin, steroids and rituximab. He was discharged with motor function gradually recovered and sensory impairment disappeared after 7 months of hospitalization. During follow-up so far, only the mobility disorder from the hip to the ankle joint remains. Our patient is hidden on the onset of the disease. At first, he appeared autonomic nervous dysfunction with abdominal pain and itchy skin, and gradually muscle tonics, which can easily lead to misdiagnosis. We summarized the diagnosis and treatment of a PERM patient, and also summarized the literature review of the report of child PERM patients to raise the awareness of pediatric neurologists. More comprehension of this disease is required to improve the early diagnosis and effects of treatment, as well as to improve the prognosis.