Heterotopic neurons in human spinal nerve roots: what is their clinical significance?

The significance of heterotopic nerve cells in human spinal nerve roots was studied. Heterotopia was a consistent finding in 230 routine necropsy series (neuropathologically normal) and 16 spinal cord malformation cases, the incidence ranging between 2.1% and 10.9%. It was more frequently found in the cervical posterior roots than in the anterior roots or in other segmental levels. The heterotopia was not increased in dysraphic anomalies. Aberrant sensory nerve cells in the posterior roots and aberrant motor cells in the anterior roots were morphologically ascertained. The clinical significance of the sensory function of the heterotopia in the anterior roots is discussed and compared with previous experimental data.