Two faces of nocturnal tongue biting.

Tongue biting associated with tonic/clonic movements of the limbs is common in epileptic patients, however nocturnal tongue biting as the only manifestation of epilepsy is rare. It can be found in frontal lobe epilepsy. Two cases with the same manifestation of nocturnal tongue biting were presented. One was the result of parasomnias-rhythmic movement disorders (RMD) and the other was a result of nocturnal frontal lobe epilepsy. The definite diagnosis of these abnormal nocturnal events was documented by prolonged EEG monitoring and polysomnography with simultaneous video studies. To our knowledge, RMD presenting with nocturnal tongue biting has never been reported in Thailand. Even in the foreign journals it has rarely been reported. It is crucial to make a definite diagnosis of RMD and nocturnal epilepsy to avoid overtreatment in the former and undertreatment in the latter. Symptomatology, diagnostic approach with therapy of these disorders were reviewed.