Denervation injury of scalp hair due to trigeminal ganglion ischemia: the first experimental study

Abstract

Aim: Scalp hairs are mainly innervated by sensitive fibers of trigeminal nerves. Ischemic neurodegeneration of trigeminal ganglion can cause denervation injury of scalp hairs. We investigated if there is a relationship between the degenerated neuron densities of trigeminal ganglion neuron densities and the numbers of degenerated hair follicles numbers following subarachnoid hemorrhage (SAH). 
 Material and Method: Five normal (n=5), five SHAM (n=5), and ten (n=10) male rabbits were chosen from formerly experimental SAH created by cisternal homologous blood injection (0.75cc) group, which followed for three weeks. Degenerated neuron numbers of trigeminal ganglion and atrophic hair follicles numbers in the frontal areas of the scalp were examined by stereological methods. Degenerated neuron densities of trigeminal ganglions and atrophic hair follicles numbers were analyzed by the Mann-Whitney U test.
 Results: The mean degenerated neuron densities trigeminal ganglions (n/mm3) and atrophic hair follicles (n/mm2) were determined as 5±2/m3 and12±4/mm2 in control; 12±3/m3 and 41±8/mm2 in Sham and, 168±23/m3 and 79±14/mm2 in the study group (p>0.001). In the post-hoc analysis, all groups differed significantly from each other. A linear association was observed between the degenerated neuron densities of trigeminal ganglions and atrophic hair follicles (r: 0.343, p: 0.007). 
 Conclusion: Trigeminal ganglion neurodegeneration may be an essential factor in hair follicles atrophy after SAH, which has not been mentioned in the literature so far.