Subacute encephalomyelitis presenting as stiff‐person syndrome: Clinical, polygraphic, and pathologic correlations

Abstract

A 60-year-old woman presented with stiff-person syndrome (SPS). Treatment with diazepam controlled her painful spasms initially. Two and one-half years after the onset of SPS, new spells of paroxysmal leg jerking and apnea developed. A spell was recorded with simultaneous video and polygraphic techniques that revealed simultaneous firing of motor unit potentials in several muscles (paraspinal, internal hamstring, and abdominal muscles). Apnea was associated with arterial oxygen desaturation. An increase in the dose of diazepam decreased the number and severity of these episodes. Seventeen months later, the patient began to taper the diazepam dose. Shortly thereafter, she had a cardiorespiratory arrest and subsequently died. Autopsy showed small chronic inflammatory foci in the pancreas (some associated with islets) and findings of diffuse encephalomyelitis characterized by perivascular cuffing in the spinal cord, brainstem, thalamus, hippocampus, and amygdala and a dense mononuclear infiltrate in the anterior horns of the lumbar and cervical cord, with relative preservation of axons and myelin. Cell typing showed this infiltrate was polyclonal and reactive. There have been rare cases of SPS associated with encephalomyelitis reported previously. Although the prolonged course in our patient suggested that SPS may have preceded encephalomyelitis, the more likely explanation is that the patient had an unusually long course of encephalomyelitis alone.

Stiff leg syndrome: Case report

“…A significant overlap exists between SPS and SLS, but recognition of SLS as a subtype may have important therapeutic and prognostic significance. To date, histological characteristics have been reported in only one patient with a clinical history consistent with SLS 12. The clinical and electrophysiological findings of our patient were similar to previous reports of SLS 10, 11.…”

Review of 23 patients affected by the stiff man syndrome: clinical subdivision into stiff trunk (man) syndrome, stiff limb syndrome, and progressive encephalomyelitis with rigidity

“…This has led to the suggestion that the rigidity and the spasms evoked by peripheral somaesthetic stimuli, voluntary action, or startle are due to a localised spinal interneuronitis 4. To date, histology has been reported in only one patient with a clinical history consistent with the stiff limb syndrome, and showed an encephalomyelitis predominantly affecting the lumbar cord 22. Indeed patients with the idiopathic stiff limb syndrome are very similar to other patients with known focal pathology preferentially involving the grey matter of the spinal cord.…”

“…Although, with one exception,22 pathological reports are lacking in the stiff limb syndrome, the condition has many clinical similarities with the jerking stiff man syndrome, in which there is increasing evidence for a polioencephalomyelitis largely indistinguishable from that found in progressive encephalomyelitis with rigidity 328 Patients with the jerking stiff man syndrome can survive more than 10 years,21 and may have evidence of an autoimmune diathesis 29.…”

Stiff Person Syndrome

“…An autopsy on 1 patient, who died of chronic obstructive pulmonary disease, showed evidence of Purkinje cell loss within the cerebellum and neuronal loss within the lateral nuclei of the ventral horn of the spinal cord, thalamus and lateral substantia nigra [115]. In a second patient who died of central apnoea, there was widespread perivascular lymphocytic infiltration in the spinal cord, brainstem, thalamus, hippocampus and amygdala, with a dense polyclonal mononuclear infiltrate within the ventral horns of the cervical and lumbar cord with preservation of axons and myelin [47].…”

“…However, more recent reports have described selective loss of GABAergic neurons within the cerebellum and spinal cord [44], or a more aggressive inflammatory picture of perivascular lymphocytic infiltration and gliosis within the spinal cord, brainstem, basal ganglia and cerebral cortex [45,46]. An autopsy on one patient, who presented initially with SPS, but died years later of PERM, showed both GABAergic neuronal attrition and evidence of perivascular lymphocytic infiltration and gliosis [47]. These recent reports suggest that, at least in the later stages of the disease, the functional GABAergic deficit results from frank neuronal loss.…”