The Role of Video-EEG Monitoring in Lesch-Nyhan Syndrome.

Lesch-Nyhan syndrome (LNS) is a rare genetic disease secondary to a HPRT1 mutation on chromosome X. It is characterized by dystonia, developmental delay, hyperuricemia and self-harming behaviours. The HPRT enzyme is implicated in the purine salvage pathway. The deficiency of HPRT results in accumulation of uric acid. There have been some cases associated with epilepsy, but it still remains a rare occurrence in LNS patients. We describe the case of a 20-month-old male patient with a heterozygous HPRT1 mutation c11_17del.p (Arg4Leufs*4) associated with LNS. The child associated epileptic seizures mistaken by his parents as non-epileptic sleep events associated with apnea. Seizures were discovered secondary to a polygraphic long-time sleep video-electroencephalography (EEG) monitoring. The dystonic movements and epileptic seizures responded to Levetiracetam, but the management of the behavioural disorder remained a challenge. Lesch-Nyhan syndrome is a rare inherited metabolic disease and its pathogenesis is not fully known, which makes the treatment management very difficult. Despite the fact that epilepsy is uncommon in LNS children, it should always be considered as part of the differential diagnosis in movement disorders. Therefore, long-term video-EEG monitoring is recommended as well as a detailed patient history to identify possible clinical/subclinical epileptic seizures that require treatment.