Management of Neuroleptic Syndrome in the Setting of Anti-Striational Antibody Myasthenia Gravis and GAD-65 Antibodies


Clinical Management

Poster Number: M258


Ryan Skowronek, DO, Michigan State University / Sparrow Hospital, Amit Sachdev, MD, Michigan State University, Samantha Leadbetter, DO, Michigan State University, Jayne Ward, DO, Michigan State University / Sparrow Hospital, Ryan Keating, DO, Michigan State University / Sparrow Hospital, Kabelo Thusang, MD, Michigan State University / Sparrow Hospital

INTRODUCTION/BACKGROUND: Neuroleptic malignant syndrome (NMS) can occur as a complication of haloperidol use, with rigidity as a primary complaint. Anti-straitional antibodies can cause a syndrome suggestive of Myasthenia Gravis (MG). In MG exacerbation, flaccid weakness and low tone are seen. The combined presentation represents a management challenge.

CASE REPORT: A 21-year-old female presents with a history of autoimmune encephalitis four years prior. Exhaustive evaluation did not reveal a known antibody disorder. At outpatient follow-up, she presented with a clinical syndrome suggestive of anti-striational antibody-positive MG. The syndrome included bulbar and oropharyngeal weakness in the absence of an elevated CPK or myopathic units on EMG. Maintenance intravenous immunoglobulin (IVIG) was successful in managing this disorder.

Her psychiatric disease persisted and evolved overtime, including the emergence of schizophrenia. Intramuscular ultra-long-acting haloperidol decanoate was initiated. In the home environment, the patient decompensated. She presented with dysautonomia, fever, encephalopathy, lead-pipe rigidity, fine tremors, fatigable ptosis, elevated CPK, and respiratory insufficiency. This combination presentation suggested a mixed disorder: NMS and MG crisis were diagnosed clinically.

IVIG alone did not appear to mitigate the burden of illness. Her medication regimen in hospital included varying combinations of dantrolene, bromocriptine, midazolam, baclofen, pyridostigmine, glycopyrrolate, and IVIG. Concern for the use of agents that could exacerbate myasthenia prompted significant discussion and intubation. As her ptosis, respiratory distress, and bulbar weakness improved, diffuse hyperreflexia emerged on serial examinations. MRI cervical spine was negative but serum GAD-65 antibody studies were floridly positive.

SUMMARY/CONCLUSION: This novel case of mixed flaccid and rigid elements in physical exam. There are positive serologic, medication exposure, and exam features for NMS, and positive serology and exam features for MG. The significance of the positive GAD-65 antibodies is difficult to ascertain, but could contribute to the mixed peripheral presentation seen in this case. (Outpatient follow-up will occur next month.)