The Initial Subjective Sensory Change in the Dermatome During Intrathecal Injection of Plain Bupivacaine Predicts the Spread of Sensory Blockade: A Prospective Multi-Level Modeling Study.

BACKGROUND: Predicting the spread of anesthesia after intrathecal injection of plain local anesthetics is challenging owing to both patient and anesthesiologist-related factors. OBJECTIVES: This study aimed to examine the initial patient-reported sensory changes during intrathecal injections and used multi-level analyses to examine the relationships between these changes and other major factors affecting the spread of anesthesia. METHODS: The participants were 120 consecutive patients with the American Society of Anesthesiologists status I and II, who were scheduled for open repair of inguinal hernias under spinal anesthesia. Lumbar puncture was performed at the midline of the L3 - L4 vertebrae and 3 mL of 0.5% isobaric bupivacaine was administered at 0.25 mL/s. The onset, dermatome, and side of the initial subjective sensory changes (ISSCs) were assessed by patient report. The extent of sensory loss to ice and pinprick stimuli, the degree of motor block in lower extremities, blood pressure, and heart rate were examined at 5-minutes intervals for 20 minutes after intrathecal injection. RESULTS: All patients reported ISSCs after 9 (4, 18) seconds [median (minimum, maximum)] of the intrathecal injection onset. In 66.7% of the patients, ISSCs occurred in the L1 - L5 dermatomes. Three patients experienced pain during the early intraoperative period, and described ISSCs in the sacral dermatome. Height, mean blood pressure, and ISSCs were significantly correlated with sensory loss. Faster onset, lower dermatome, and floor-side of ISSCs predicted a narrower area of sensory loss, with dermatome as the most important indicator. CONCLUSIONS: Our findings demonstrate that ISSC, primarily based on dermatome, is a significant predictor for spinal anesthesia spread.

Immediate analgesic effect of 8% lidocaine applied to the oral mucosa in patients with trigeminal neuralgia.

BACKGROUND: Trigeminal nerve block is widely used for trigeminal neuralgia (TN), though with much painful procedure and potential serious complications. The pain of TN occurs most frequently in the second and the third divisions of the trigeminal nerve, which are distributed in intraoral mucous membrane as well as face skin. Here, we examined the response to intraoral application of 8% lidocaine (LDC) in patients with oral TN pain in a double-blind, placebo (PBO)-controlled crossover study. METHODS: Twenty-four outpatients with oral TN pain were randomized to receive intraoral application of either 8% LDC or saline PBO to the painful area. Following 7-days period, patients were crossed over to receive the alternative treatment. The pain was assessed with a numerical rating scale (NRS) before and 15 minutes after treatment. Patients used a descriptive scale to grade pain outcome and were asked to note any recurrence and the latency for recurrence after therapy. RESULTS: Intraoral LDC, but not PBO, significantly decreased the NRS from 5 (4, 8) (median [25, 75 percentiles]) to 1 (0, 4) (P = 0.001). Of the 24 patients, 19 described marked or moderate relief of pain after LDC but only three described the same after PBO application. The effect of LDC and PBO persisted for 2.8 (0.3, 3.0) and 0 (0, 0) hours, respectively. CONCLUSIONS: Intraoral application of 8% LDC produced prompt analgesia without serious side effects in patients with TN who presented with severe intraoral pain.

Lidocaine eye drops attenuate pain associated with ophthalmic postherpetic neuralgia.

BACKGROUND: Topical lidocaine (LDC) treatment using a gel or patch preparation is effective in the treatment of postherpetic neuralgia (PHN), but neither is suited for the eye in patients with ophthalmic PHN. Herein, we examined the effect of LDC 4% eye drops on ophthalmic PHN pain. METHODS: Twenty-four patients with ophthalmic PHN were randomized to receive 0.4 mL eye drops of either LDC 4% or saline placebo (PBO) in the painful eye. After a 7-day period, the patients were crossed over to receive the alternative eye drops. The pain in the eye and the forehead was assessed with a visual analog scale (VAS) before and 15 minutes after treatment. Patients used a descriptive scale to grade pain outcome and were asked to note whether the pain returned and how long after therapy it recurred. RESULTS: LDC significantly decreased the VAS score of persistent pain in the eye (baseline: 5.9 +/- 2.2 cm; 15 minutes after eye drops: 0.9 +/- 1.8 cm, mean +/- SD [P < 0.01]) and in the forehead (baseline: 6.3 +/- 2.0 cm; 15 minutes after eye drops: 2.6 +/- 2.7 cm [P < 0.01]). The delta change in these VAS scores between LDC and PBO was significant (P < 0.01). Moreover, pain was described as moderate or better by 23 patients after they received LDC and 4 patients of the PBO group. The effect of LDC persisted for a median of 36 hours (range, 8-96 hours) after application. CONCLUSIONS: This study suggests that LDC provides a significant improvement of ophthalmic PHN because of its prompt analgesia, lack of systemic side effects, and convenience of use.

Efficacy of a metered-dose 8% lidocaine pump spray for patients with post-herpetic neuralgia.

OBJECTIVE: Topical lidocaine patch is effective in the treatment of post-herpetic neuralgia (PHN), but not suited for paroxysmal pain because of the long latency of analgesia. Here, we examined the efficacy of 8% lidocaine pump spray (Xylocaine pump spray, XPS) for PHN. DESIGN: Twenty-four patients with PHN were recruited into a randomized, double-blind, placebo-controlled, crossover study (study 1), and 100 patients with PHN were recruited into an open-labeled study (study 2). In study 1, patients were randomized to receive either XPS or saline placebo pump spray (PPS) applied to the painful skin areas. Following a 7-day period, patients were crossed over to receive the alternative treatment. In study 2, XPS was prescribed for patients who were advised to use the spray anytime, with a 2-hour gap between applications, for 2 weeks. The pain was assessed with a visual analogue scale (VAS). Details of use were noted in the diary. RESULTS: In study 1, greater decreases in VAS of persistent pain followed application of XPS (baseline: 6.1 +/- 1.7 cm, 15-minute post-spray: 2.3 +/- 2.5 cm, mean +/- SD) than with PPS (6.1 +/- 1.7 cm, 5.7 +/- 1.6 cm, [P < 0.01]). The effect persisted for a median of 4.5 hours (range, 2 to 24 hours) after application. In study 2, 13 of 100 patients discontinued the treatment because of mild local side effects or insufficient effect. In the remaining 87 patients, XPS maintained significant pain relief relative to baseline throughout the 2-week period. Satisfaction with the therapy was reported by 79% of patients. CONCLUSIONS: In both studies, XPS provided a significant improvement in PHN due to its prompt analgesia, lack of systemic side effects, and convenience of use.