Authors :
Presenting Author: Shreeja Kadakia, MD – St. Luke’s University Health Network
Presenting Author: Kuei-Cheng Lim, MD, PhD – St. Luke's University Health Network
Brian Hanrahan, MD – Epileptologist, Neurology, St. Luke's University Health Network; Kuei Lim, MD, PhD – Epileptologist, Neurology, St. Luke's University Health Network
Rationale:
Tongue biting is generally recognized as a discernable marker of generalized tonic-clonic seizures. Thi single clinical symptom has a reported sensitivity of 24% and a specificity of 99% (Benbadis SR, Wolgamuth BR, Goren H, Brener S, Fouad-Tarazi F. Value of tongue biting in the diagnosis of seizures. Arch Intern Med. 1995 Nov 27;155(21):2346-9). There are few other phenomena that can cause comparable tongue injury. Tongue biting occurs due to forceful activation of masseter, orbicularis oculi, oris muscles during sleep. In this case report, we review a rare sleep disorder called sleep-related facio-mandibular myoclonus that was initially misdiagnosed as epilepsy due tongue biting being its the primary manifestation.
Methods: Case report
Results: A 69-year-old female with a remote history of febrile seizures (six months to three years of age) was admitted to our institution’s Epilepsy Monitoring Unit (EMU) for spell characterization. She had reported nightly sleep-related episodes of tongue biting. A witness of the episodes reported no confusion or unresponsiveness associated with these episodes. Levetiracetam and lacosamide were initially trailed with no improvement.
During her six day EMU admission, a total of nine typical events of tongue bite during sleep were captured during non-REM sleep. Event EEG recordings revealed normal sleep activity until a < 100 ms EMG artifact and subsequent arousal from sleep occurred. No abnormal cortical activity was seen during the events. On videography, there was an abrupt, mouth closure and audible “click” of the teeth biting down associated with the transient EMG artifact. There were no interictal findings to suggest an underlying seizure disorder despite completely weaning off of her anti-epileptic drugs (AEDs) during the admission. Figures 1 and 2 show two examples of the pattern of interest on a bipolar montage; these epochs show a drowsy or light sleep state followed by a burst of EMG artifact and arousal from sleep.
Based on videography and EEG/EMG data, these events were determined to be non-epileptic in nature and due to sleep-related facio-mandibular myoclonus. The patient was started on clonazepam 0.5 mg nightly for the parasomnia and had her AEDs discontinued. At her three month follow up visit, the patient reported that the frequency of nocturnal myoclonus was significantly reduced.
Conclusions:
Patients with sleep-related facio-mandiular myoclonus are often initially misdiagnosed with sleep-related seizures due to its prominent presenting clinical feature: sleep-related tongue bites. These patients are often started on anti-epileptic medications without significant symptomatic improvement. Video EEG monitoring with surface EMG for spell capture can be helpful in confirming the diagnosis.
Funding: None.