Richard H. Gelberman

The carpal tunnel syndrome. A study of carpal canal pressures.

We measured intracarpal canal pressures with the wick catheter in fifteen patients with carpal tunnel syndrome and in twelve control subjects. The mean pressure in the carpal canal was elevated significantly in the patients. When the wrist was in neutral position, the mean pressure was thirty-two millimeters of mercury. With 90 degrees of wrist flexion the pressure increased to ninety-four millimeters of mercury, while with 90 degrees of wrist extension the mean pressure was 110 millimeters of mercury. The pressure in the control subjects with the wrist in neutral position was 2.5 millimeters of mercury; with wrist flexion the pressure rose to thirty-one millimeters of mercury, and with wrist extension it increased to thirty millimeters of mercury. Carpal tunnel release brought about an immediate and sustained reduction in pressure.

The vascularity of the scaphoid bone

The extraosseous and intraosseous vascularity of the carpal scaphoid was studied in 15 fresh cadaver specimens by injection and clearing techniques. The major blood supply to the scaphoid is via the radial artery. Seventy to eighty percent of the intraosseous vascularity and the entire proximal pole is from branches of the radial artery entering through the dorsal ridge. Twenty to thirty percent of the bone, in the region of the distal tuberosity, receives its blood supply from volar radial artery branches. There is an excellent collateral circulation to the scaphoid by way of the dorsal and volar branches of the anterior interosseous artery. An explanation for the cause of scaphoid necrosis on the basis of the vascular anatomy is proposed. The volar operative approach would be least traumatic to the proximal poles blood supply.

Median nerve compression in the carpal tunnel—Functional response to experimentally induced controlled pressure

Controlled external compression was applied to the median nerve of 16 volunteer subjects. Tissue fluid pressure in the carpal canal was monitored with a wick catheter and pressures of 30, 60 and 90 mm Hg were induced for periods varying from 30 to 90 minutes. Sensory and motor conduction and two-point discrimination were continuously monitored. Tissue compression at 30 mm Hg caused mild neurophysiological changes and symptoms of hand paresthesias. Compression at both 60 and 90 mm Hg induced a rapid, complete sensory conduction block which consistently preceded a motor block by 10 to 30 minutes. Frequently, two point discrimination remained normal until the last stages of preserved sensory fiber conduction. In three cases, a modification of the model utilizing an arm tourniquet, demonstrated that ischemia rather than mechanical deformation was the primary cause of the functional deterioration. It was concluded that there is a critical pressure level between 30 and 60 mm Hg where nerve fiber viability is acutely jeopardized.

The Importance of Controlled Passive Mobilization on Flexor Tendon Healing: A Biomechanical Study

The effects of controlled passive motion on primary tendon repair were studied using the canine forepaw flexor apparatus as experimental model. The animals were divided into seven groups based on duration(3 to 12 weeks post repair) and mode of immobilization and partial mobilization. The repaired tendons were subjected to biomechanical evaluation of their gliding function and tensile strength characteristics. The results showed positive effects of controlled passive motion on tendon repair. The rate of tendon repair was significantly improved over those animals that were continuously immobilized. At 12 weeks, the repaired flexors from the motion group had regained over one-third of the ultimate tensile load as compared to their contralateral intact controls. Of equal importance is that these repaired tendons maintained good gliding function within the sheath during the repair process. The gliding function of these tendons was also significantly better than those subjected to continuous immobilization.

In vivo regeneration of cut nerves encased in silicone tubes: growth across a six-millimeter gap.

We describe an experimental in vivo system for studying peripheral nerve regeneration, in which the proximal stump of a transected nerve regrows through a transparent silicone chamber toward the distal stump. Physical separation permits examination of the effects of the humoral and/or cellular influences from the distal stump on regenerating fibers before they invade the distal segment itself. A small segment of the rat sciatic nerve was resected, leaving a 6 mm gap which was then encased by a cylindrical silicone chamber. Within the first weeks, a nerve trunk regenerated along the central axis of the chamber bridged the gap between the proximal and distal stumps. When the distal nerve stump was omitted from the distal opening of the chamber, only a thin structure with a few small-caliber fibers extended across the gap. In each instance regenerating nerve appeared as a cord-like structure completely surrounded by clear fluid, a feature which permits easy collection of the extracellular fluid for analysis of its chemical properties and biological activity. This feature also allows in vivo manipulation of the humoral environment in which nerve regeneration occurs.

Sensibility testing in peripheral-nerve compression syndromes. An experimental study in humans.

Sensibility testing in peripheral-nerve compression syndromes was investigated in an experimental study in humans. Twelve volunteer subjects had controlled external compression of the median nerve at the carpal tunnel at a level of forty, fifty, sixty, and seventy millimeters of mercury. The subjects were then monitored for thirty to 240 minutes with four sensory tests: two-point discrimination, moving two-point discrimination, Semmes-Weinstein pressure monofilaments, and vibration. Sensory and motor conduction, subjective sensations, and motor strength were also continuously tested. The threshold tests (vibration and Semmes-Weinstein monofilaments testing) consistently reflected gradual decreases in nerve function in both subjective sensation and electrical testing, while the innervation density tests (two-point discrimination and moving two-point discrimination) remained normal until nearly all sensory conduction had ceased. Decreased muscle strength occurred late, and not until changes had already occurred in each of the sensory tests. Threshold tests of sensibility correlated accurately with symptoms of nerve compression and electrodiagnostic studies, and are being evaluated for clinical use in a variety of peripheral-nerve compression syndromes.

Carpal tunnel syndrome. An evaluation of the provocative diagnostic tests.

In order to evaluate the usefulness of provocative tests (wrist-flexion test, nerve-percussion test, and tourniquet test) in the diagnosis of carpal tunnel syndrome, the results of provocative testing were evaluated in a group of patients (sixty-seven hands) with electrodiagnostically proved carpal-tunnel syndrome and in a group of fifty control subjects. The sensitivity and specificity of each test were calculated. The wrist-flexion test was found to be the most sensitive while the nerve-percussion test, although least sensitive, was most specific. The tourniquet test was quite insensitive and not very specific, and should not be used as a routine screening test in the diagnosis of carpal tunnel syndrome.

The vascularity of the lunate bone and Kienbock's disease

The extraosseous and intraosseous vascularity of the lunate was studied in 35 fresh cadaver limbs. The specimens were injected with latex, debrided by a nondissection technique, and cleared by a modified Spalteholtz method. The extraosseous vascularity was profuse through two to three dorsal and three to four volar vessels feeding dorsal and volar capsular plexuses. One ot two nutrient vessels were observed entering the dorsal and volar poles of the lunate from both plexuses. The intraosseous vascularity formed one of three consistent patterns with anastomoses of dorsal and volar vessels in each specimen. The vascular patterns support a theory of compression fracture from repeated trauma as the most likely cause of Kienböcks disease.

Results of treatment of severe carpal-tunnel syndrome without internal neurolysis of the median nerve.

Thirty-three hands (twenty-nine patients) had a release of the carpal tunnel without internal neurolysis for severe carpal-tunnel syndrome. All of the hands had increased values for two-point discrimination or thenar atrophy, or both. Twenty-three (89 per cent) of the twenty-six hands that had increased values for two-point discrimination and twenty-six (87 per cent) of the thirty hands that had an elevated result on Semmes-Weinstein testing had normal values at follow-up. Nine (90 per cent) of the ten hands that had weakness of the thenar muscles (grade-3 strength or less) regained grade-4 or 5 strength. Thirteen (65 per cent) of the twenty hands that had thenar atrophy regained normal muscle bulk. Eighteen (62 per cent) of the twenty-nine patients had complete resolution of symptoms and signs of compression of the median nerve. No significant difference was found between the results in this series of patients and those in a previously reported similar group of patients who were treated by release of the carpal tunnel combined with internal neurolysis of the median nerve.

Sensibility testing in patients with carpal tunnel syndrome.

We evaluated the sensibility of the hand preoperatively and at intervals postoperatively in twenty-three hands of twenty patients with idiopathic carpal-tunnel syndrome who underwent carpal tunnel release. Tests of sensibility included the threshold tests (vibrometry, 256-cycles-per-second vibration, and Semmes-Weinstein monofilaments) and one innervation-density test (two-point discrimination). In addition the wrist-flexion test, nerve-percussion test, and tourniquet test were performed preoperatively. Only five of the twenty-three hands had abnormal two-point discrimination and each of these also had markedly abnormal threshold-test values. Nineteen of twenty-three hands preoperatively had decreased sensibility detected by both Semmes-Weinstein monofilament testing and vibrometry. Six weeks after carpal tunnel release, all of the hands demonstrated improvement on threshold testing, and 65 per cent had normal values.