200 Section - Stiff-Person Syndrome Following West Nile Virus Infection and Insights for Multimodal Rehabilitation

Stiff Person Syndrome (SPS) is a rare autoimmune neurological disorder characterized by axial rigidity, painful spasms, and impaired GABAergic inhibition, associated with anti-GAD65 antibodies. It has been hypothesized that infections may trigger SPS through molecular mimicry. We report a case of SPS developing shortly after West Nile Virus (WNV)-associated polyradiculopathy in an immunosuppressed patient with autoimmune hepatitis.

In September 2024, a 44 years-old immunosuppressed woman presented with fever, malaise and proximal lower-limb weakness with subsequent spontaneous improvement. One month later, EMG was normal except for iliopsoas nonspecific findings, complete spine MRI revealed diffuse cauda equina root enhancement, and serology confirmed WNV infection, consistent with viral polyradiculopathy.


Case Description:

In November 2024, she was re-hospitalized for recurrent weakness, new painful abdominal and paraspinal spasms with marked lower-limb hypertonia, gait impairment, and kinesiphobia, with preserved reflexes. Repeat MRI showed improved radicular enhancement. PET-scan and brain MRI were unremarkable. EMG demonstrated reduced recruitment and spontaneous activity consistent with acute/subacute polyradiculopathy, along with continuous motor activity and superimposed contraction bursts without distractibility, supportive of SPS. Serum and CSF anti-GAD65 were markedly elevated, while all other autoimmune markers were negative.

Treatment included clonazepam, plasmapheresis, IVIG, and corticosteroids, followed by intensive rehabilitation. She improved with maintenance therapy combining botulinum toxin injections, IVIG every three weeks, clonazepam, IV solumedrol, and ongoing multidisciplinary rehabilitation.


Discussions: This case highlights that SPS may emerge after WNV infection, even following post-viral polyradiculopathy and despite immunosuppression, suggesting that residual autoimmunity remains sufficient to trigger disease expression. It also supports the effectiveness of a multimodal treatment strategy combining pharmacological therapy, botulinum toxin injections despite denervation, and intensive multidisciplinary rehabilitation in improving functional outcomes in SPS.

Conclusions:

This case underscores the complex interplay between viral infections and autoimmune neurological disorders, and the effectiveness of a comprehensive multimodal treatment.