Objective: To present a case of rapid onset Stiff Person Syndrome (SPS) in a non-classic patient and review diagnostic considerations associated with his presentation.

Background: SPS is a rare disorder, typically autoimmune or paraneoplastic in origin, characterized by fluctuating rigidity and stiffness of axial and proximal lower limb musculature with superimposed spasms and continuous motor unit activity on EMG.¹  We present a case of SPS with an atypical onset.

Method: A 24-year-old male presented with 1 week of left lower extremity pain and spasms that rapidly progressed to debilitating lumbosacral back, bilateral leg, and bilateral arm spasms. On examination, he was noted to have severe opisthotonus with dystonic posturing of his upper extremities and extensor posturing of both lower extremities. Brief periods of truncal extensor posturing lasting seconds accompanied by bilateral shoulder abduction were also observed. He was also found to have significant contraction of paraspinal muscles as well as increased tone and limited ROM at knees and elbows resulting in inability to ambulate. Symptoms had significant albeit transient improvement with valium. After diagnoses of SPS was confirmed, he received 3 days of IVIG and was started on Tizanidine. Examination after treatment was notable for resolution of opisthotonus and dystonic posturing with movement, normal tone, and normal strength. He was able to ambulate without any assistive device and was discharged home.

Results: EMG/NCS exteroceptive reflex testing revealed hyperexcitability with stimulation of the right median nerve (Figure 1B). Serum workup including CBC, CMP, peripheral smear, TSH, PTH, AST, ALT, CK, folate, Vitamin B12, MMA, ceruloplasmin, Cu, Zn, GAD 65 were within normal levels. CTA intra/extracranial and MRI brain and cervical spine did not reveal significant abnormalities. At time of abstract write up, serum anti-ampiphysin and paraneoplastic panel were pending.

Conclusion: Here we show a non-classic patient presentation of SPS. Initial diagnostic considerations at presentation included seizure, acute dystonia, and functional/psychosomatic disorder. Although a rare disorder, SPS should be a diagnostic consideration in patients presenting with rigidity (diffuse and/or lateralizing as in this patient’s case) and spasms and may sometimes begin with stiff limb syndrome (classically a leg) before progressing to SPS. Treatment with benzodiazepines and/or IVIG can result in dramatic improvement in symptoms.

References: 1. Hadavi, S., Noyce, A.J., Leslie, R.D., & Giovannoni, G. (2011). Stiff person syndrome. Practical neurology. 11, 272-282.

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