A method for the determination of the length, the critical resection length and the critical gap distance of peripheral nerves from external body dimensions.

In 68 human corpses over the age of 20 years, defined external body dimensions and the total lengths of peripheral nerves were measured, taking sex and constitutional type into consideration. The particular body dimension with the closest correlation to the lengths of the most frequently injured nerves of the extremities was determined by correlation computation. Using this external body dimension in regression equations and diagrams, it is possible to determine the average length of the nerves of the extremities with considerable accuracy directly in the patient. When the length of the nerve is known, the absolute value of the critical resection length of 3 per cent and the critical gap distance of 3-7 per cent (depending on the kind of nerve and the level of the separation) can be determined individually.

What governs the size of the retraction gap in divided peripheral nerves.

The retraction gap in severed peripheral nerves form a part of the critical gap distance. It thus contributes to determining its size. The extent of retraction of severed nerves is variable and depends on joint movements. However, the individual distributions of the retraction gap are more or less constant and remain unaffected in various joint positions. The mean gap size is related to the level of nerve section and it becomes smaller as one moves distally. The degree of retraction increases in a wider, and decreases in a narrower section of the course of the nerves. In consequence of the existing attachments of each nerve to its bed there is inhibition of retraction, but much freer retraction is possible when these attachments are eliminated.

A study on the critical mobilization length of peripheral nerves.

The transverse section of the sciatic, tibial and peroneal nerves in rabbits was followed by mobilization in a proximal and distal direction and a tension-free end-to-end suture of the cut surfaces. The proximal mobilization was performed up to eight different levels between 60 mm and 200 mm, i. e. 20.3% to 67.7% of the total nerve length. Histological findings and their statistical analysis indicated that the critical mobilization length, beyond which ischaemic parenchymal damages occur, is 70 mm or 24% of the total nerve length. Up to this level, the vascular "extrinsic system" of the mobilized nerve segments is completely compensated for by the "intrinsic system". When the mobilization length is increased, the degeneration distances were more pronounced than those of the ischaemic nerve distances. Some nerves showed no effects from the ischaemia.

Facilitation of removal of a hypervascularized cervical vertebral body tumour by intraoperative temporary occlusion of the tumour-feeding vertebral artery, using intraarterial catheterization.

The surgical treatment of a highly vascularized tumour that destroyed the fourth cervical vertebral body in a young patient, without neurological deficits, is reported. After posterior stabilization an anterior approach was used in order to replace the affected vertebral body with an acrylic prosthesis. The tumour-feeding vessels originated largely from the right vertebral artery. In order to maintain optimal visibility, intraoperative haemorrhage was kept at a minimum by temporarily occluding the tumour-feeding vertebral artery with an intraarterial catheter.

Mechanical loading of peripheral nerves during remobilisation of the affected member after end-to-end anastomosis.

Our study involved simulating end-to-end neurorrhaphy of the sciatic nerve in a number of rabbits and analysing in vivo the mechanical loads acting on the nerve while the affected member was being remobilised. We found both the suture and mobilisation loads to be related to the size of the nerve defect. In each case, traction force, strain, and stress were proportional. The effect which these experimental findings may have on the future use of flexing neighbouring joints as a "manipulative" measure to achieve a tension-free nerve suture will be discussed.