Congenital trigeminal anaesthesia. A review and classification.

Forty-three patients with the syndrome of congenital trigeminal anaesthesia (CTA) have been reported to date. The cases have been divided into three groups based on the presence and nature of any associated clinical problems. Three additional cases are presented as characteristic of each of the groups. A different aetiology is proposed for each group. Group I consists of patients with CTA as an isolated finding. It is almost always bilateral, and typically involves the distribution of only the first division of the fifth nerve. There is no evidence of other neurological abnormalities or associated mesoectodermal congenital anomalies. The aetiology is suspected to be a primary neural hypoplasia. Patients with associated congenital mesenchymal anomalies were placed in the second group. CTA was often a minor part of another well defined, more extensive clinical syndrome, such as Möbius or oculoauriculovertebral dysplasia (OAVD). The sensory abnormality was either unilateral or bilateral. The skin of the face was almost always involved, as well as the cornea and conjunctiva. This may be a heterogenous group with multiple aetiologies having in common an injury early in embryogenesis. The third group is defined as patients with CTA without evidence of mesenchymal dysplasia. These cases differ from the first group primarily because of the presence of associated focal brainstem signs. The aetiology is thought to be due to focal neural dysgenesis secondary to a prenatal injury, possibly vascular in nature.