George J. Hayes

Experimental Improvements in the Use of Silastic Cuff for Peripheral Nerve Repair

F OR nearly 90 years experimental and clinical evidence has favored structural support about a nerve repair 7,~7 with a material that permitted direct and reproducible maximal axonal spanning without axonal disorganization or connective tissue build-up. Only during the past year has such a material become available. 4 This material, Silastic, formed into thin, elastic tubes was tested in chimpanzees against thicker tubes of the same material, wraps of millipore, collagen, or silicone, and against standard epineural suturing without wrapping. The results have been promising? However, ill-fitting tubes, regardless of the material, can strangulate a nerve anastomosis if too tight or fail to support it if too loose. 13 Therefore, establishing the best cuff dimensions, including such specifications as the proper ratio between the cross-section area of the nerve and the tube, became an important prerequisite to clinical trials. This report describes refinements in the technical details of nerve repair utilizing a Silastic cuff.

ACUTE HAEMORRHAGIC LEUCOENCEPHALITIS (HURST) WITH A CONCURRENT PRIMARY HERPES SIMPLEX INFECTION.

In 1941 Hurst described a rapidly progressive acute disease of the central nervous system which he named acute haemorrhagic leucoencephalitis. It is a rare disorder; less than 40 cases have been reported, and its aetiology is still unknown. Before 1963, the reported cases of acute haemorrhagic leucoencephalitis had been diagnosed after death. We have had the opportunity, however, to treat a patient who developed the disease and recovered. The diagnosis was established upon microscopic examination of an amputated temporal lobe. During the early stages of the illness his serum showed a significant rise of the complement-fixing antibody titre to herpes simplex. We have a two-fold purpose in presenting this case report. First, the opportunity for follow-up evaluation of patients with proven acute haemorrhagic leucoencephalitis is rarely encountered; consequently, we are prompted to make the data which we collected generally available. Secondly, we wish to consider the significance of the unprecedented association which was established between acute haemorrhagic leucoencephalitis and a primary herpes simplex infection.

The value of an A‐mode echoencephalogram display

THE TERM A-mode ultrasonics signifies that returning ultrasonic energy is represented by height of deflections on the ordinate of the oscilloscope screen. This is the display used by most commercially available equipment. The term B-mode signifies that returning energy is represented by brightness of light at a point on the abscissa and that the ordinate is free to represent either passage of time (time modulation) or movement of the probe in space (Bmode scanning). The potential value of B-mode scanning appears to fully warrant the evaluation it is receiving, despite its greater cost of purchase and upkeep and limitations to clinical use. However, B-mode scanning has one inherent limitation that will be most difficult to overcome: it is not a dynamic study. A-mode and time-modulated B-mode ultrasonics are the oiily studies in routine use that show the rhythmic changes of intracerebral anatomical relations that result from the pulsatile influx of blood and give perspective lacking in more detailed, but static, procedures. No unphysioIogica1 change is produced, and data are continuous rather than taken in limited number at arbitrary intervals. Ultrasonics thus offers a unique opportunity to study intracerebra1 hemodynamics. For example, the width of the third ventricle shown by an echoencephalogram may vary synchronously with the pulse, a finding shown cinemagraphically by Dr. hlcKinney.1 This implies that in borderline cases, the diagnosis of third ventricular enlargement by pneumoencephalography may depend on the chance pulse phase occurring when the radiograph was taken, and it appears possible that, on occasion, the ventricular width may fluctuate just above and below an arbitrary chosen limit of normal. It is possible to modify echoencephalography for cerebral scanning and obtain a two-dimensional picture of cerebral structures.394 This may scmetimes be desirable, but the second