Fibrous structures in the subarachnoid space: a study with spinaloscopy in autopsy subjects

The lumbar and lower thoracic subarachnoid space of 26 human autopsy subjects was studied using rigid endoscopy, spinaloscopy. Fibrous attachments were found between nerve roots and/or nerve roots and the arachnoid membrane at least at one spinal level in 16 subjects. The appearance and density of the structures varied, and caused restriction of nerve root mobility in nine subjects. In three of them, the impeded mobility prevented the nerve root from yielding to the contact and pressure exerted either by the tip of the endoscope or by a spinal needle introduced into the subarachnoid space. In another three subjects, a distinct membranous structure was identified in the posterior midline of the subarachnoid space in the lower thoracic and upper lumbar regions. These findings may possibly be associated with the variation in the extent of subarachnoid block and to the development of isolated nerve root trauma in connection with this procedure.