Refractory and lethal status epilepticus in a patient with ring chromosome 20 syndrome

The only consistent symptom of ring chromosome 20 syndrome (r(20)) is severe, refractory epilepsy often associated with a characteristic, although not pathognomonic, EEG pattern. Patients suffer from severe seizures with accompanying cognitive decline and frequent episodes of non-convulsive status epilepticus (SE). Other features of this rare disorder, such as dysmorphic changes, mental retardation and behavioral disturbances are variable. Because of the variability of the clinical presentation, some patients with r(20) undergo invasive investigations before being diagnosed.

We present the case of a young boy with no dysmorphic traits, who was only diagnosed with r (20) syndrome at the age of 13. His first seizure occurred at the age of four. Later seizures were of various types including non-convulsive SE, with deterioration of the background EEG and severe cognitive decline. Despite multiple trials of anti-epileptic medications, his seizures remained highly refractory, and he died as the result of an uncontrollable, prolonged SE, shortly after the diagnosis was made.

Non-convulsive SE is common in patients with r(20) syndrome and may be caused by a dysfunction in dopaminergic neurotransmission. However, until now, no case of lethal status epilepticus has been reported. This case report suggests that patients with unexplained refractory seizures and episodes of non-convulsive SE should undergo genetic testing early in their disease, even in the absence of any morphologic features or dysmorphic traits suggestive of a chromosomal disease.