Histograms. Histograms for myelinated (left) and unmyelinated (right) fibres. A: grand average for three autopsy specimens (Pennisi et al. ). B: Patient 0. C: grand average for six patients with trigeminal isolated sensory neuropathy (TISN). D: grand average for four patients with facial-onset sensory motor neuronopathy (FOSMN). Myelinated fibres in patients with trigeminal neuronopathy are unimodally distributed and the two conditions yield similar histograms.