LAUSR

Propriospinal myoclonus (PSM) at sleep onset is characterized by jerks of axial muscles, spreading caudally and rostrally, during the transition from wakefulness to sleep1. We present a rare case of a patient who suffered severe sleep-onset insomnia due to PSM after metoclopramide use during pregnancy. A 30-year-old woman with a history of well-controlled herpes simplex virus (HSV) and a resected atypical serous borderline ovarian tumor with microinvasion, presented after a 2-year bout of insomnia due to electrical, jerking sensations in her torso, spreading to the legs just before falling asleep. The symptoms began after an 18-week trial of metoclopramide 20mg, for severe reflux with esophagitis during pregnancy, and persisted after discontinuation of metoclopramide, and postpartum, periodically worsening with menses. On first presentation, the neurological exam was unremarkable; polysomnography was conducted, showing brief myoclonic jerks of the upper extremity, with increased EMG tone and muscle artifact, preventing sleep onset, allowing a total sleep time of merely 1 hour 10 minutes. Event - related recordings on simultaneous electromyogram (EMG)/electroencephalogram (EEG), showed mixed movement disorder and suggested mild CNS hyperexcitability with some volitional muscle jerks, and some myoclonic jerks. An earlier trial of clonazepam 1mg nightly partially improved her symptoms, but caused panic, suicidal ideation, and depression. Month-long, nightly Diphenhydramine 50mg and Trazodone 100mg initially helped with insomnia, while Doxepin 10mg/mL, Daridorexant 25mg, Tizanidine, Gabapentin 900mg, Zolpidem, Cyclobenzaprine, Levetiracetam 500mg, Carbidopa-Levodopa, and sleep restriction all proved ineffective. Eventually, she underwent another trial of clonazepam at 0.25mg with slow titration to 0.75mg while adding melatonin 10mg, without adverse effects noted. Our case of PSM at sleep onset was in the context of metoclopramide use during pregnancy. Uniquely, adverse effects were associated with a higher and rapid titration of Clonazepam, but later improved with a lower dose and slower titration, coupled with Melatonin. Notably, both dopamine agonists and antagonists, also cannabis, nitric oxide, interferon, ciprofloxacin, bupivacaine, spinal anesthesia, all have reportedly caused medication-induced myoclonus. Further, reports on similar cases may aid in understanding better the pathophysiology of this rare, disabling condition, and lead to more rapid, effective treatment.