A Case of Hyperekplexia That Started From Childhood: Clinical Diagnosis With Negative Genetic Investigations

Abstract

Here, we report the case of a 63-year-old woman affected by abnormal, excessive, and involuntary reactions to harmless and unexpected sensory stimuli, compatible with the diagnosis of hyperekplexia. It is a pathology that involves the glycinergic system on a hereditary basis, and even if genetic proof compatible with the diagnosis is not present in this case, the fact that an aunt on her father's side suffered from the same disorders supports the clinical suspicion. From an early age, clinical history shows anomalous motor manifestations, initially framed as a form of focal epilepsy or ordinary disorders of the mood sphere, later excluded by the lack of effectiveness of a targeted therapy. Despite this, intellectual, psychological, and socio-emotional development was regular. The manifestations, present throughout childhood, adolescence, and early adulthood in moderate entity, worsened after the age of 50, perhaps due to hormonal changes. The presence of consequent anxiety and depression has compromised her quality of life, and in order to improve it, therapies were resorted, which, however, produced cognitive-attention deficits. No diagnostic exam has confirmed the diagnosis, although some scars in some brain areas involved in the control of reactions are elements favorable to this condition in genetically predisposed subjects. Therapies currently in use attenuate the motor symptomatology without resolving it and cause side effects in the psychological and cognitive sphere. In this case, we want to highlight the difficulty of diagnosing a very rare genetic condition, still not well-known, which presents symptoms easily mistaken for other more common diseases, because there are no specific clinical-diagnostic tools for the time being. In this particular case, we describe a female patient with an atypical onset age and negative genetic investigations compared with what is known in literature regarding this rare disorder. That is why it has been thought she was affected by epilepsy or anxiety-related disorders for several years.

Keywords: Kok disease; glycinergic system; hyperekplexia; hyperkinesis; startle disease.