Supraspinal anesthesia: behavioral and electroencephalographic effects of intracerebroventricularly infused pentobarbital, propofol, fentanyl, and midazolam.

BACKGROUND: Anesthetic endpoints of unconsciousness and immobility result from agent effects on both brain and spinal cord that are difficult to separate during systemic administration. To investigate cerebral mechanism of anesthetic-induced unconsciousness, the authors studied behavioral and electrophysiologic effects of four anesthetics infused intracerebroventricularly to conscious rats. The authors aimed to produce progressively increasing anesthetic depths, indicated by electro-encephalographic synchronization and behavioral change. METHODS: During anesthesia, rats were equipped with intracerebroventricular infusion catheters, hind-paw stimulation, and epidural electrodes to record the electroencephalogram from the somatosensory cortex. Silicone bolus was injected into the fourth ventricle to minimize drug distribution to the spinal cord. 60 min later, 50-min infusion of pentobarbital (6.0 mg/h), fentanyl (0.75 microg/h), propofol (3.0 mg/h), or midazolam (0.24 mg/h) was initiated. Vibrissal, olfactory, corneal, and tail-pinch responses were tested every 10 min. RESULTS: All agents depressed vibrissal, olfactory, and corneal responses; propofol and pentobarbital produced the strongest effect. All agents except propofol depressed tail-pinch response; fentanyl and pentobarbital produced the strongest effect. All agents except midazolam increased delta power. Pentobarbital enhanced theta power. All agents except fentanyl enhanced alpha and beta power. Pentobarbital and midazolam slightly increased, whereas fentanyl decreased, gamma power. Pentobarbital increased and midazolam decreased somatosensory evoked potential; these changes were small and apparently unrelated to behavior. CONCLUSIONS: Alpha and beta power increase may reflect sedative component of anesthesia. Simultaneous delta, alpha, and beta power increase may correlate with loss of consciousness. Theta and delta power increase may reflect surgical anesthesia. Opioid-induced gamma power decrease may reflect suppression of pain perception. Pentobarbital-, fentanyl-, and midazolam-induced immobility to noxious stimulation may be mediated supraspinally.

Carpal tunnel release by limited palmar incision vs traditional open technique: randomized controlled trial.

AIM: To compare a limited palmar incision for carpal tunnel release (CTR) with a traditional open technique, which is still considered the gold standard. METHODS: Seventy-two patients with a carpal tunnel syndrome were individually randomized into the trial (limited incision CTR) (n=36) and control group (traditional technique CTR) (n=36). In the trial group, skin incision parallel to the thenar crease was made up to 2.5 cm in length, under an operating microscope and endoscopic transillumination. Skin incision in the control group began at the distal border of the carpal ligament, followed the longitudinal crease of the palm, and crossed the base of the palm in a zigzag fashion. Three months after surgery, the patients were asked about symptomatic relief and intervals between the operation and return to their daily activities and work, and examined for scar tenderness and esthetic outcome. Distal motor latency, conduction velocity, scar length, scar width, and operation time were measured. RESULTS: There were no differences between the two groups in symptomatic relief and electrophysiological parameters. Intervals between the operation and return to daily activities (median 5 days, range 2-15) were shorter in the trial group than in the control group (median 10 days, range 2-21; p<0.001), as well as the intervals between the operation and return to work (median 15 days, range 5-45 vs median 30 days, range 10-60; p<0.001). Scar/pillar tenderness, scar length and width, esthetic outcome, and operation time were significantly better in the trial group. CONCLUSION: Limited palmar incision CTR is as effective and safe as traditional CTR technique, but with better postoperative recovery and cosmetic results.