Anatomic conditions for bypass surgery between rostral (T7-T9) and caudal (L2, L4, S1) ventral roots to treat paralysis after spinal cord injury.

Severe spinal cord injuries cause permanent neurological deficits and are still considered as inaccessible to efficient therapy. Injured spinal cord axons are unable to spontaneously regenerate. Re-establishing functional activity especially in the lower limbs by reinnervation of the caudal infra-lesional territories might represent an effective therapeutic strategy. Numerous surgical neurotizations have been developed to bridge the spinal cord lesion site and connect the intact supra-lesional portions of the spinal cord to peripheral nerves (spinal nerves, intercostal nerves) and muscles. The major disadvantage of these techniques is the increased hypersensitivity, spasticity and pathologic pain in the spinal cord injured patients, which occur due to the vigorous sprouting of injured afferent sensory fibers after reconstructive surgery. Using micro-surgical instruments and an operation microscope we performed detailed anatomical preparation of the vertebral canal and its content in five human cadavers. Our observations allow us to put forward the possibility to develop a more precise surgical approach, the so called "ventral root bypass" that avoids lesion of the dorsal roots and eliminates sensitivity complications. The proposed kind of neurotization has been neither used, nor put forward. The general opinion is that radix ventralis and radix dorsalis unite to form the spinal nerve inside the dural sac. This assumption is not accurate, because both radices leave the dural sac separately. This neglected anatomical feature allows a reliable intravertebral exposure of the dura-mater ensheathed ventral roots and their damage-preventing end-to-side neurorrhaphy by interpositional nerve grafts.

Anastomotic patterns of the facial parotid plexus (PP): A human cadaver study.

Details of the human facial parotid plexus (PP) are not readily accessible during ordinary anatomical teaching because of insufficient time and difficulties encountered in the preparation. For parotid and facial nerve surgery however, precise knowledge of PP is of crucial importance. The aim of this study was therefore to provide more details of PP in anatomic specimens. Following anatomical dissection, its location, syntopy and morphology were analyzed in 158 cervico-facial halves of 95 cadavers. The facial nerve (FN) divides into a larger temporo-facial and a smaller cervico-facial trunk. Both trunks branch, form PP, and thus form connections along six distinctive anastomotic types. These anastomoses may explain why accidental or essential severance of a supposed terminal facial branch fails to result in the expected muscle weakness. However, whereas earlier anatomical and clinical studies report connections between both trunks in 67-90% of the cases, our data indicate the presence of anastomoses only in 44%. One reason for this difference may be found in our microscope-assisted dissection in infratemporal regions from which the parotid gland has been removed. Thereby we tracked both FN-trunks in both directions - distally and proximally - and determined the exact origin of all terminal FN branches. This lower rate of occurrence of connections between both trunks reduces the chances of luckily preserved muscle innervation and enhances the risk of facial palsy after transection of a terminal branch. Accordingly, precise anatomical knowledge on PP should be renewed and transection of facial nerve branches avoided.

Topography, syntopy and morphology of the human otic ganglion: a cadaver study.

The human otic ganglion (OG) is not readily accessible during ordinary anatomical teaching courses because of insufficient time and severe difficulties encountered in dissection. Accordingly, most anatomical descriptions of its location, relation to neighbouring structures, size and shape are supported only by drawings, but not by photographs. The aim of this study has been to present the OG with associated roots and branches in dissected anatomic specimens. Following cumbersome dissection and precise photo-documentation, a detailed analysis of location, syntopy and morphology was performed. We carried out this study in 21 infratemporal fossae of 18 cadavers and were able to identify the OG, the mandibular-, the inferior alveolar- and the lingual nerve in all of them. We found no significant variation regarding the location of the GO in the infratemporal fossa and its syntopy to the adjacent structures. An OG resembling the classic description was found only in 90.50% of the cases. All 3 roots (parasympathetic, sympathetic and sensory) could be identified only in 82.3% of the specimens. The established presence of ganglionic branches varied from 0% (communicating rami to the meningeal branch of the mandibular nerve, to the greater petrosal nerve and to the lingual nerve) to 90% (r. communicans to n. canalis pterygoideus). We conclude that precise knowledge of this enormous variety might be very helpful not only to students of medicine and dentistry during anatomical dissection courses, but also to head and neck surgeons, ear-nose-throat specialists and neurosurgeons when treating pathology of pre- and postganglionic fibres.