Atypical Presentation of Lance Adams Syndrome in the setting of Clonazepam overdose and SARS-CoV-2 pneumonia

ABSTRACT

Objective: To report an atypical presentation of Lance-Adams Syndrome presenting from severe respiratory depression rather than cardiac arrest and to highlight the importance of distinguishing it from post hypoxic myoclonic variants. Background: Clinicians often face difficulty distinguishing Lance-Adams Syndrome (LAS) from Myoclonic Status Epilepticus (MSE). Similarities between the two conditions frequently result in confusion when diagnosing, managing and prognosticating for post-hypoxic myoclonus patients. Design/Methods: A 23-year-old male with a history pertinent for Hemophilia B, depression, opiate and alcohol abuse and chronic pain was found down in his home next to an empty bottle of clonazepam. He was hypoxic with oxygen saturation in the 40s and intubated in the field. Upon arrival to the Emergency room, neurological examination revealed intact corneal reflexes but no gag reflex, cough, or purposeful movements of the extremities. The patient exhibited stimulus induced myoclonic jerking which lasted >30 minutes despite being loaded on valproic acid and levetiracetam. Jerking subsequently ceased with propofol drip. Chest X-ray confirmed interstitial opacities and tested positive for SARS-CoV-2. On attempting to wean sedation, patient exhibited full-body myoclonus including face and palate with inability to follow commands and lack of spontaneous movements. As the EEG showed BIPEDS greater than 2.5 HZ, we decided to burst suppress him and treat with targeted temperature management. After 10 days, the patient was successfully weaned from sedation and extubated, but remained on multiple anti-seizure medications. Results: Patient responded well despite his diffuse cerebral anoxic injury. He regained the ability to follow commands upon discharge but had residual moderate expressive aphasia and post-hypoxic action-induced myoclonus, consistent with LAS. Conclusions: The atypical presentation of this case emphasizes the importance of distinguishing LAS from MSE to guide neurologists to aggressively treat LAS to improve outcome, particularly since MSE historically results with a 90-100% mortality rate.