We report a healthy teenager with involuntary nocturnal tongue biting resulting in recurrent tongue injury. Causes for tongue biting during sleep in children include seizures, bruxism, faciomandibular myoclonia, hypnic myoclonia, and rarely geniospasm, which has been described as a rare inherited movement disorder accompanied with chin quivering. In the absence of family history, we diagnosed our patient with sporadic geniospasm based on polysomnographic findings with good response to clonazepam. Geniospasm should be considered in the differential diagnosis of cases with unexplained tongue injury in sleep.
Mahmoudi M, Kothare SV. Tongue biting: a case of sporadic geniospasm during sleep. J Clin Sleep Med 2014;10(12):1339-1340.
Geniospasm is a rare movement disorder with the hallmark of paroxysmal, rhythmic up-and-down movements of the chin and the lower lip with accompanying involuntary contractions of the mentalis muscle. Geniospasm has been described as an autosomal dominant inherited condition with high penetrance, linked to chromosome 9q13-q21.1 Episodes of geniospasm last from seconds to hours and may be provoked by emotion, stress, or concentration, but can also occur without apparent precipitants.2 Symptoms typically manifest in early childhood, and tend to diminish with advancing age.1,3 As yet, few cases of inherited geniospasm with nocturnal tongue biting among other symptoms have been described, and only one case of sporadic geniospasm with typical clinical presentation has been delineated.1,3,4 To our knowledge, we report the first case of sporadic geniospasm with tongue biting solely during sleep.
REPORT OF CASE
We evaluated a 17-year-old right-handed healthy Hispanic boy with recurrent tongue biting exclusively during sleep. Events started around age 12, occurring on average twice a week and were associated with tongue laceration of varying severity. Neither the patient nor his parents were aware of precipitating factors or any other symptoms associated with these events. His physical exam was only notable for multiple tongue scars, mostly at the tip of the tongue. He did not have signs or symptoms suggestive of bruxism. His general and neurological examination was unremarkable, his development was normal, and he was an average student. He denied intake of alcohol, illicit substances, or medications. Interview of family members ascertained absence of a similar condition in relatives in at least 2 prior generations. Results of computed tomography, magnetic resonance imaging, and multiple 24-h ambulatory and routine electroencephalograms were normal. The patient did not warrant metabolic work-up given his normal cognitive function and lack of developmental regression in milestones.
Overnight polysomnography (Figure 1) revealed periods of involuntary tremor of the chin and lower lip on video monitoring, coinciding with increased EMG tone, with no electrographic seizure. Test results were suggestive of geniospasm during sleep. The patient showed excellent clinical response to clonazepam 0.5 mg at bedtime, and has not experienced further tongue biting on clonazepam for the past 12 months.
Overnight polysomnography showed increased EMG tone coinciding with chin trembling (1-Hz rhythmic activity lasting up to 10 seconds); interictal EEG was completely unremarkable throughout the night without any epileptiform discharges including sleep potentiated centro-temporal spike-wave complexes.
Overnight polysomnography.Overnight polysomnography showed increased EMG tone coinciding with chin trembling (1-Hz rhythmic activity lasting up to 10 seconds); interictal EEG was completely unremarkable throughout the night without any epileptiform discharges including sleep potentiated centro-temporal spike-wave complexes.
Various conditions can result in tongue biting during sleep in children, including seizures, bruxism, faciomandibular myoclonia, hypnic myoclonia, and rarely geniospasm. Geniospasm is a rare inherited movement disorder, with reports of 500 people in fewer than 40 families worldwide. Paroxysmal rhythmic up-and-down movements of the chin and the lower lip are characteristic for this condition, but other neurological features such as nystagmus, involuntary tongue biting, myoclonia, or REM behavior disorder have also been observed. Hereditary geniospasm exhibits almost complete penetrance2; however, this has been put into question by reports of several unaffected obligate gene carriers.1 In addition, one case of sporadic geniospasm has been described in the literature, presenting with typical clinical manifestation similar to the hereditary form.3 We present a case of involuntary nocturnal tongue biting in sleep resulting in recurrent tongue injury with excellent clinical response to low-dose clonazepam. Unlike chin quivering in geniospasm, faciomandibular myoclonia is characterized by sudden forceful vertical myoclonic jaw movements and is often associated with a tapping teeth sound.5 Tongue biting due to hypnic myoclonia, has been described at a much younger age and has been considered an age-dependent phenomenon related to brain maturation and development of oral functions.6
Geniospasm is generally described as a benign condition, but in our case, the recurrent tongue injury caused major discomfort and reduced quality of life. This atypical presentation with lack of family history could be explained by reduced penetrance or possibility of a new mutation. Geniospasm, independent of family history, should be considered in the differential diagnosis of cases with unexplained tongue injury in sleep. Sleep physicians should pay attention to significant intermittent rhythmic EMG artifacts on EEG channels (Figure 1) coinciding with jaw and tongue movements and/or chin trembling on video monitoring to diagnose these rare movement disorders. If necessary, additional EMG electrodes could be placed near the masseters to obtain additional information.
This was not an industry supported study. The authors have indicated no financial conflicts of interest.