The dorsal column system. 1. Existence of long ascending postsynaptic fibres in the cat's fasciculus gracilis

333 NEUROLOGY The dorsd column system. II. Functional properties postsynaptic fibres of the cat’s fasciculus gracilis D. Angaut-Petit,

and bulbar relay of the

Exp. Brain Res., 22 (1975) 471-493

The postsynaptic posterior column fibers described in the previous abstract were examined for their stimulus sensitivities to natural stimuli. 16% were activated by intermittent mechanical stimuli and not by a constant pressure, 77% were activated by gentle and noxious mechanical and thermal stimuli, both warm and cold, and a few responded only to mechanical noxious stimuli, such as pinching the skin with a clip. The primary afferent fibers of the posterior columns are not activated by noxious or thermal stimulation. The author conjectures that these postsynaptic fibers might not contribute to the feeling of pain, but that they could influence the pain experienced by reducing the input of a major cutaneous somatosensory pathway to higher centers during noxious stimulation.

Stereotactic

extralemniscal

myelotomy

J.R. Schvarcz, J. Neurol. Neurosurg,

Psychiat.,

39 (1976) 53-57

For the treatment of causalgia, post-herpetic neuralgia, painful dysesthesiae, tearing of the brachial plexus and pain in cancer, the author makes a lesion, under local anesthesia, through the midline at the ce~ico-rned~la~ junction. This lesion causes “subjective analgesia”, there being no objective sensory loss in most cases; but occasionally there was loss of objective pain sensibility “in the lower half of the body”. The relief of the patient’s pain was totally unrelated to the occurrence of objective loss of pain sensibility, The operation caused no unwanted side-effects. Disturbances of walking did not last more than 48 h.

The dorsal column system. 1. Existence in the cat’s fasciculus gracilis D. Angaut-Petit,

of Iong ascending postsynaptic

fibres

Exp. Brain Res., 22 (1975) 457-470

Microelectrode recordings were made from posterior column fibers while the sciatic nerve was stimulate electrically. Posterior column fibers were also stimulated antidromic~ly, and the collision technique between anti- and orthodromic conduction was used. Activity in two kinds of fibers was encountered: primary afferent fibers and postsynaptic fibers. The importance

334 of this study is its demonstration that long ascending fibers are not exclusively primary afferent fibers. There are also fibers ascending in the posterior columns with their cell bodies in posterior horns. About 800 of these postsynaptic fibers were fired from the skin and about 500 from deep structures. Their conduction rates were between 16 and 55 m/set. -. .GENERAL Postprandial

SURGERY rest pain and claudication

D. H. Brooks and K.M. Bron, Surgery,

of the lower extremity 78 (1975) 677-681

A clinical case of the Leriche syndrome is reported. The patient complained of postpr~dial rest pain and severe postpr~dial in~rmittent claudication in left calf. The arteriogram revealed that the abdominal aorta was occluded just below the origin of the renal arteries. Lumbar collateral vessels were poor, and left-sided deep circumflex iliac collateral was not found. It was concluded that perfusion of the left lower extremity was dependent upon collateral arterial pathways from the superior mesenteric arterial circulation. Eating led to increase in mesenteric blood flow and to decrease in collateral circulation to lower extremities. The inadequacy of the collaterals was thought to be the cause of symptoms. Endarterectomy of the aorta and aortofemoral reconstruction was performed, and resulted in total relief of all symptoms. Unmyelinated axons in human ventral roots, a possible failure of dorsal rhizotomy to relieve pain R.E. Coggesh~l, M.L. Applebaum, Sykes, Brain, 98 (1975) 157-166

M. Fazen,

explanation

T.B. Stubbs,

for the

III and M.T.

There are large numbers of unmyelinated sensory fibers in cat ventral roots, It is important to determine by electron microscopy whether significant numbers of unmyelinated fibers can be found in human ventral roots. The present study demonstrates that large numbers of unmyelinated axons were found in 3 human ventral roots aged 17,21 and 24. To estimate the number of unmyehnated fibers in a fascicle or root, the follow~g equation can be used: Total number of myelinated fibers in the fascicle (.LM) Sample of myelinated fibers in a thin section of the same fascicle (EM)

Sample of unmyelinated fibers in the same thin X section of the fascicle (EM)

Estimated total number of un= myelinated fibers in a fascicle.