Partial Stiff Person Syndrome as a Stroke Mimic (5382)

To report a rare case of a patient presenting with unilateral symptoms whose work-up revealed partial stiff person syndrome (SPS).

SPS is an immune-mediated neurological disorder characterized by rigidity of muscles, superimposed upon disabling spasms and heightened sensitivity to external stimuli. SPS is subdivided into several categories, including the classical type and its variants such as partial SPS.

Our patient is a 62 year old female with no prior medical problem who presented to the hospital with right arm and leg weakness as well as a body locked sensation where she felt muscle stiffening and could not move. She also described random, large amplitude involuntary movements either in her right arm or right leg. No symptoms in her left side. She was admitted for suspected stroke in November 2018 and had extensive workup including MRI brain with contrast which did not show any area of enhancement nor acute DWI. No cause for her symptoms was found, and after discharge continued to have worsened right sided ataxia and hyperreflexia and increased muscle tone. Further work-up ensued, and it was not until April 2019 that she was found to have an elevated GAD (>250 IU/mL) and HbA1C 6.3 with positive islet cell antibody. Lumbar puncture results showed positive GAD65 Ab Assay (3.09 nmol/L) and the presence of oligoclonal bands.

The patient was diagnosed with partial SPS, and was trialed on baclofen and then diazepam but did not tolerate these. She was subsequently started on intravenous immunoglobulin treatment, almost one year after the onset of her symptoms.

Partial SPS a subtype noted in only 10 to 15 % of patients, and classification gives important diagnostic and prognostic information. Recognition of classic SPS vs variants is important because appropriate therapy like IVIg improves symptoms in most patients and should be initiated without delay.

Disclosure: Dr. Machado has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with USWorldMeds, Lundbeck, Adamas, Ipsen, Amneal, Teva, Neurocrine. Dr. Hodges has nothing to disclose.