A relationship between bruxism and orofacial-dystonia? A trigeminal electrophysiological approach in a case report of pineal cavernoma

Abstract

BackgroundIn some clinical cases, bruxism may be correlated to central nervous system hyperexcitability, suggesting that bruxism may represent a subclinical form of dystonia. To examine this hypothesis, we performed an electrophysiological evaluation of the excitability of the trigeminal nervous system in a patient affected by pineal cavernoma with pain symptoms in the orofacial region and pronounced bruxism.MethodsElectrophysiological studies included bilateral electrical transcranial stimulation of the trigeminal roots, analysis of the jaw jerk reflex, recovery cycle of masseter inhibitory reflex, and a magnetic resonance imaging study of the brain.ResultsThe neuromuscular responses of the left- and right-side bilateral trigeminal motor potentials showed a high degree of symmetry in latency (1.92 ms and 1.96 ms, respectively) and amplitude (11 mV and 11.4 mV, respectively), whereas the jaw jerk reflex amplitude of the right and left masseters was 5.1 mV and 8.9 mV, respectively. The test stimulus for the recovery cycle of masseter inhibitory reflex evoked both silent periods at an interstimulus interval of 150 ms. The duration of the second silent period evoked by the test stimulus was 61 ms and 54 ms on the right and left masseters, respectively, which was greater than that evoked by the conditioning stimulus (39 ms and 35 ms, respectively).ConclusionsWe found evidence of activation and peripheral sensitization of the nociceptive fibers, the primary and secondary nociceptive neurons in the central nervous system, and the endogenous pain control systems (including both the inhibitory and facilitatory processes), in the tested subject. These data suggest that bruxism and central orofacial pain can coexist, but are two independent symptoms, which may explain why numerous experimental and clinical studies fail to reach unequivocal conclusions.

Decreased γ‐aminobutyric acid levels in the brainstem in patients with possible sleep bruxism: A pilot study

“…These data indicate that the inhibitory circuits that innervate trigeminal motoneurons are less excitable in SB patients . However, in a case report in which the patient was affected by pineal cavernoma and pronounced bruxism, the author indicated that bruxism and central oro‐facial pain can coexist but represent 2 independent symptoms . The interneural sensitisation observed during the recovery cycle of MIR might be linked to a combination of the excitatory effect of glutamate and the disinhibition of the inhibitory process that results from the effects of glycine and GABA .…”

“…However, in a case report in which the patient was affected by pineal cavernoma and pronounced bruxism, the author indicated that bruxism and central oro‐facial pain can coexist but represent 2 independent symptoms . The interneural sensitisation observed during the recovery cycle of MIR might be linked to a combination of the excitatory effect of glutamate and the disinhibition of the inhibitory process that results from the effects of glycine and GABA . Finally, the observed alterations could increase the firing probability of trigeminal motoneurons during sleep, resulting in RMMA.…”

What should a dentist be aware of concerning symptoms of sleep disorders in the oral cavity?

“…Dystonia is a movement disorder leading to similar damage in tooth hard tissues as that caused by bruxism. Dystonia is a disorder of involuntary, repetitive, predominantly sustained (tonic), or spasmodic (rapid or clonic resembling myoclonus) muscle contractions [17]. Dystonia may affect almost all striated muscle groups in different body regions.…”

The Reliability of the Bilateral Trigeminal Roots-motor Evoked Potentials as an Organic Normalization Factor: Symmetry or Not Symmetry?

“…It should also be noted that in a very small proportion of OP patients visited by dental specialists, some neurological diseases as intracranial cancers, multiple sclerosis and so on are the underlying symptomatological cause of TMD or OP. These patients, who actually suffer from misunderstood neurological symptoms, may undergo unnecessary dental interventions before the correct diagnosis is made, often too late [7,8].…”