Recurrent Nocturnal Tongue Biting in a Case of Hereditary Geniospasm

Hereditary geniospasm, also known as hereditary chin trembling, is a rare condition in which intermittent, repetitive contractions of the bilateral mentalis occur resulting in a quivering or trembling appearance to the chin and lower lip. ¹ Generally, its course is believed to be benign, and treatment is often sought due to social embarrassment. ¹ , ²

Rarely, significant complications may occur. Specifically, recurrent nocturnal tongue biting (RNTB), can be associated with geniospasm and is often the presenting complaint in children seeking treatment. ¹ , ² , ³ , ⁴ , ⁵ , ⁶ The association of RNTB and hereditary geniospasm as well as urgency of treatment is often underrecognized.

Case Report

An 11‐month‐old, previously healthy male presented to our movement disorders center with tongue biting during sleep. He was born full term after an uncomplicated pregnancy and since the first day of life was noted to have paroxysmal trembling of his chin “as if he were about to cry” and occurred sporadically lasting seconds to minutes. Family history was significant for father, paternal aunt, and paternal grandmother all with similar chin trembling. At 9 months of age, he would awaken from sleep crying, and was noted to have blood covering his pillow and within his mouth. This worsened over the following weeks with increased amounts of blood and awakenings occurring every 20 min, and a portion of his tongue appeared amputated (Fig. 1). Within a month, he developed decreased appetite with weight loss. His development had been typical until the tongue biting was noted after which he had decreased speech and was increasingly irritable. His parents began holding his jaw while he slept in 4 hour shifts to prevent his biting. Tongue biting always occurred with the chin trembling in sleep. Family sought care at several institutions prior to presentation during which an electroencephalogram and brain MRI were performed and found to be normal. Geniospasm was captured on EEG without electrographic correlate. His physical examination was normal apart from geniospasm and tongue amputation with scarring (Video 1).

Figure 1.

Tongue amputation and injury with scarring present in the patient seen in (A) and (B).

Video 1.

Patient at initial evaluation with geniospasm seen lasting seconds. Also seen is scarring of the patient's tongue due to recurrent nocturnal tongue biting.

He was admitted and treated with clonazepam (gradually titrated to 0.05 mg/kg/day divided three times daily over the course of one week) given his sleep was not regulated and injury occurred during naps with unpredictable timing. Botulinum neurotoxin (BoNT) injections were also initiated to the bilateral masseter and mentalis muscles. Initially, BoNT was dosed at 50 units each masseter and 15 units each mentalis and subsequently increased to 80 units and 20 units respectively of OnabotulinumtoxinA due to early wearing off with recurrence of RNTB. Within 2 weeks of treatment, he had complete resolution of biting. While clonazepam lessened the severity of biting, resolution was achieved following BoNT injections. Furthermore, the irritability resolved, he had improved oral intake with weight gain, and speech returned to baseline. He has tolerated treatment well without adverse effects and has continued treatment for almost a year thus far. There was no change in geniospasm with initiation of clonazepam, however, 2 weeks after BoNT, geniospasm resolved (similarly there was early wearing off after initial injections which resolved with increased dosing).

Discussion

Here a case is presented in which the presenting symptom was severe RNTB with associated geniospasm. Hereditary geniospasm is a rare condition with less than 500 reported cases in the literature. ² Although geniospasm is hereditary with an autosomal dominant inheritance pattern, no causative gene has yet to be identified. ¹ Within these cases of geniospasm, 9–12% also have associated RNTB ¹ , ² which range from mild, with small lacerations of the tongue, to severe, as in this case, with amputation of a portion of the tongue with loss of speech, weight loss, sleep fragmentation, and persistent irritability. ¹ , ³ , ⁴ , ⁵ , ⁶

Onset of RNTB in geniospasm often occurs between 9 and 18 months of age and decreases during early childhood. Some may have persistence into adulthood; however, the frequency and severity are often improved. ¹ The underlying mechanism of RNTB is poorly understood, however is theorized to be related to sleep‐related faciomandibular myoclonus which is a focal hypnic jerk involving muscles of mastication (vs. mentalis in geniospasm) resulting in similar tongue injury and similarly responsive to benzodiazepines. ¹ , ⁶ , ⁷ Treatment of geniospasm is often pursued as its spontaneous or stress related chin quivering can lead to social anxiety and embarrassment. BoNT is the preferred treatment with doses ranging from 5 to 60 units to each mentalis. ² In the case of RNTB, treatment can involve benzodiazepines, BoNT to the masseters (and potentially temporalis muscles), and in severe cases such as this, a combination. ¹ , ² , ³ , ⁴ , ⁵ , ⁶

This patient experienced several complications due to the severity of his RNTB to include decreased speech with failure to progress in language development, weight loss, irritability, and sleep fragmentation. Complications were alleviated with prompt and aggressive treatment leading to resolution of symptoms and illustrates the urgency of recognition and treatment in these cases.

Author Roles

(1) Research project: A. Conception, B. Organization, C. Execution; (2) Manuscript Preparation: A. Writing of the first draft, B. Review and Critique.

M.H.: 1A, 1B, 1C, 2A, 2B.

Disclosures

Ethical Compliance Statement: No IRB was required for preparation of this case report, ethical guidelines were followed to assure patient privacy was maintained. Written consent from patient guardians was obtained prior to obtaining photo/video for purposes of education within a medical peer reviewed journal. I confirm that I have read the journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines.

Funding Sources and Conflicts of Interest: The author declares that there are no conflicts of interest relevant to this work.

Financial Disclosures for the Previous 12 Months: Dr. Hull received honoraria from MedLink Neurology for article contributions unrelated to this case. The institution of Dr. Hull has received research support from the NIH and PTC Therapeutics unrelated to this case.