Role of degenerated neuron density of dorsal root ganglion on anterior spinal artery vasospasm in subarachnoid hemorrhage: experimental study

The spinal arteries are innervated by several systems that contribute to the control of spinal cord blood flow. The sensory fibers of upper cervical nerves have vasodilatatory effect on the anterior spinal arteries (ASA). Subarachnoid hemorrhage (SAH) causes severe vasospasm by various neurochemical mechanisms. We examined whether there is a relationship between the neuron density of the C3 dorsal root ganglion and the severity of ASA vasospasm in SAH. This study was conducted on 20 rabbits. Four of them were used as baseline group. Experimental SAH has been applied to all of 16 animals by injecting homologous blood into cisterna magna. After 20 days of injection, ASA and C3 dorsal root ganglia (C3DRG) were examined histopathologically. ASA volume values and normal and degenerated neuron densities of C3DRG were estimated stereologically and the results were analyzed statistically. The mean ASA volume was 1,010 +/- 450 mm(3), and the mean neuronal density of C3DRG was 10,500 +/- 850 in all animals. The mean volume value of ASA was 970 +/- 150 mm(3), and the normal neuron density of C3DRG fell to 8,600 +/- 400/mm(3) in slight vasospasm group. In severe vasospasm-developed animals, mean volume value of ASA was 540 +/- 90 mm(3) and the normal neuron density of C3DRG fell to 5,500 +/- 360/mm(3). An inverse relationship between the degenerated neuronal density of the C3DRG and ASA volume values may indicate the severity of ASA vasospasm. The neuron density of C3DRG may be an important factor on the regulation of ASA volume values and the continuation of spinal cord blood flow. Low neuron density of C3DRG may be considered as an important factor in the pathogenesis of severe ASA vasospasm in SAH.