An evaluation of the incisive nerve block and combination inferior alveolar and incisive nerve blocks in mandibular anesthesia

The purpose of this study was to measure the degree of anesthesia obtained with the incisive nerve block, the inferior alveolar nerve block and a combination of both injections in mandibular teeth. Using a repeated measures design, 40 subjects randomly received an incisive nerve block, a conventional inferior alveolar nerve block, or a combination inferior alveolar nerve block plus an incisive nerve block using either lidocaine or saline (control), at four successive appointments. The mandibular teeth and contralateral canine (+/- controls) were blindly tested with an Analytic Technology pulp tester at 4-min cycles for 60 min. An 80 reading indicated complete pulpal anesthesia. The incisive nerve block alone did not result in successful pulpal anesthesia in the central, lateral, first, and second molars. It was successful in the first and second premolars but the duration was approximately 30 min. The combination inferior alveolar nerve block plus incisive nerve block was successful in the first and second premolars, and enhanced anesthesia for the laterals and first molars.     

Localized hypertrophic neuropathy involving the inferior alveolar nerve

OBJECTIVE: To determine the effects of immunodeficiency, nutritional status, and concurrent systemic disease on peripheral nerve function in acquired immunodeficiency syndrome. DESIGN: Survey of subjects infected with human immunodeficiency virus (HIV), recruited as part of a prospective study of neuromuscular complications of HIV infection. SETTING: A neuro-acquired immunodeficiency syndrome outpatient clinic in a university medical center. PATIENTS: A consecutive sample of 251 HIV-infected individuals. Primary care providers referred subjects to the study for evaluation of neurologic symptoms or for prospective neurologic assessment. MAIN OUTCOME MEASURES: Standardized history and neurologic examination, laboratory tests (complete blood cell count, serum albumin level, vitamin B12 level, and T-lymphocyte subsets), and electrophysiologic testing of sural, tibial, and ulnar nerves. RESULTS: The most frequent neurologic diagnosis was distal symmetrical polyneuropathy (DSP) (38%). The most common clinical features were nonpainful paresthesias (71%), abnormalities of pain and temperature perception (71%), and reduced or absent ankle reflexes (66%). Patients with DSP were significantly older (P=.009), and had lower CD4 lymphocyte cell counts (P=.004) and lower hemoglobin levels (P=.004) than those without DSP. Deterioration of values on nerve conduction studies, irrespective of the clinical diagnosis of DSP, was significantly correlated with low CD4 counts, aging, abnormal serum albumin and hemoglobin levels, and weight loss. Most of these factors co-correlated, and, with the exception of age, no single variable significantly accounted for changes in results of nerve conduction studies when the influence of other factors was eliminated. CONCLUSION: The combination of several factors, including age, immunosuppression, nutritional status, and chronic disease, contributes to distal peripheral nerve dysfunction in HIV infection.     

Endodontic-related inferior alveolar nerve and mental foramen paresthesia

Paresthesia is a condition that involves perverted sensations of pain, touch, or temperature. It has a variety of possible causes. This article presents a literature review and case reports of endodontically related inferior alveolar nerve and mental foramen paresthesia. Nondrug prevention methods and the dental uses of dexamethasone are also discussed.     

Neuropeptide immunoreactivity in ligature-induced neuromas of the inferior alveolar nerve in the ferret

Injury to branches of the trigeminal nerve can sometimes result in persistent dysaesthesia. In an attempt to understand the aetiology of this condition we are currently investigating changes which occur at the injury site. In the present study we have examined the expression of seven neuropeptides, all of which have been implicated in nociceptive transmission, or have previously been shown to have altered expression following nerve injury. In 20 adult ferrets the inferior alveolar nerve was sectioned and ligated, and recovery permitted for 3 days, 8 days, 3 weeks, 6 weeks or 12 weeks. Longitudinal sections of the neuromas were processed using immunohistochemical techniques to quantify the expression of substance P, calcitonin gene-related peptide, vasoactive intestinal polypeptide, galanin, somatostatin, enkephalin and neuropeptide Y. After 3 days, all of the neuropeptides were expressed at the injury site. In the neuromas examined after longer recovery periods these levels of expression had declined and were similar to those found in the contralateral controls. This initial high level, followed by a decline, parallels the incidence of ectopic neural activity recorded electrophysiologically in the same model. It is, therefore, possible that the accumulation of neuropeptides at the injury site may play a role in the initiation or modulation of ectopic neural activity.     

Controlled release of lidocaine from injectable gels and efficacy in rat sciatic nerve block

PURPOSE: Methods of delaying the action of local anesthetics are important, since short duration of action limits their use in the treatment of postoperative and chronic pain. The present study evaluated the use of low-viscosity gels in prolonging the release of lidocaine. METHODS: Release of lidocaine from 2% lidocaine.HCl containing methylcellulose (MC), hydroxypropylmethylcellulose (HPMC), sodiumcarboxymethyl cellulose (CMC), and poloxamer 407 (PO) gels was studied in phosphate buffer, pH 7.4, at 37 degrees C. Commercial metylcellulose gel (MCcom) served as control. The in vivo efficacy of the respective gel formulations were evaluated in rats. The gel was injected into the vicinity of the sciatic nerve and nociception and motor function were tested. RESULTS: The cumulative amount of lidocaine released during 8 hr was slowest from the PO gel, followed by the CMC, HPMC and MC gels. The antinociceptive effect was not prevented by the motor block and lasted longest with the PO gel. Good linear and rank order correlation was obtained between in vitro and in vivo results. The microscopic examination of the tissue samples revealed only mild or no irritation of the skeletal muscle tissue by the PO, HPMC, and CMC gels. CONCLUSIONS: Based on these results poloxamer gel proved to be the most promising carrier for lidocaine.     

Infection-related mental and inferior alveolar nerve paresthesia: literature review and presentation of two cases

A review of the literature on infection-related mental and inferior alveolar nerve paresthesia is given. This is followed by 2 case reports. The first case is of a mandibular left second molar in which a chloropercha overfill puff occurred in the vicinity of the inferior alveolar canal. The tooth remained asymptomatic until 2 and 1/2 yr later, when the periapical lesion enlarged and swelling, pain, and paresthesia developed. The paresthesia resolved 2 weeks following periapical surgery. The second case is of a mandibular right first premolar in which paresthesia began 1 day after the initial endodontic treatment. The intracanal medication was formocresol on a cotton pellet that was squeezed dry. The paresthesia was treated by irrigation, antibiotics, and dexamethasone. The paresthesia lasted 7 weeks, and when it resolved the root canal was filled with gutta-percha/eucapercha. Almost 9 months later, the tooth remained asymptomatic.     

Mandibular fracture after endosseous implant placement in conjunction with inferior alveolar nerve transposition: a patient treatment report

A patient with a severely atrophic right posterior mandible had three endosseous implants placed in conjunction with transposition of the inferior alveolar nerve. Three weeks following implant placement surgery, the patient experienced a spontaneous fracture of the mandible involving the two anterior implants. The two implants were removed, and the fracture was treated with open reduction and fixation with titanium mesh. The fracture healed, and the posterior implant integrated. This report suggests that the buccolingual and superior-inferior position of the mandibular canal can increase the possibility of mandibular fracture by increasing the size of the buccal cortical plate that is removed to expose the nerve during surgery.     

NGF depletion reduces ipsilateral and contralateral trigeminal satellite cell reactions after inferior alveolar nerve injury in adult rats

The degradation of poly(propylene fumarate-co-ethylene glycol) hydrogels was examined in vitro in phosphate-buffered saline at pH 7.4 and in vivo in a subcutaneous rat model. These hydrogels have potential application as biodegradable, injectable cardiovascular stents, and, as such, their mass loss, dimensional changes, mechanical properties, morphology, and biocompatibility over a 12-week time course were evaluated. Three formulations were fabricated: one base formulation consisting of 25% (w/w) PEG, molecular weight 4,600; one high weight percent PEG formulation with 50% (w/w) PEG; and one high molecular weight PEG formulation, molecular weight 10,500. All three formulations showed significant weight loss (between 40 and 60%) on the first day due to leaching of the uncrosslinked fraction. Further weight loss was observed only for the low weight percent PEG copolymers in the in vivo case, and a slight increase in volume was observed due to degradative swelling. The mechanical properties of the P(PF-co-EG) hydrogels decreased significantly in the first 3 weeks, showing the biphasic pattern typical of bulk degradation. In vitro, the hydrogels showed at least a 20% retention of their initial ultimate tensile stress after 3 weeks. The dynamic mechanical properties showed similar retention, with the in vivo mechanical properties differing from the in vitro properties only after 6 weeks of degradation. Differences in PEG molecular weight appeared to have little effect, but increasing the weight percent PEG decreased the rate of degradation both in vitro and in vivo. The morphology of the copolymer films, based on scanning electron microscopy observation, was not significantly different either among the three formulations or over the time course of the study, suggesting there were no macroscopic structural changes during this time period. The P(PF-co-EG) hydrogels demonstrated good initial biocompatibility, showing responses characteristic of biomaterial implants.     

Effect of intravenous lidocaine on halothane minimum alveolar concentration in ponies

This study investigated the effect of lidocaine i.v. on halothane minimum alveolar concentration (MAC) in ponies. Six ponies were anaesthetised with thiopentone and succinylcholine, intubated and anaesthesia maintained with halothane. Ventilation was controlled and blood pressure maintained within clinically acceptable limits. Following a 2 h equilibration period, baseline halothane MAC was determined. The ponies were then given a loading dose of lidocaine (2.5 or 5 mg/kg bwt) or saline over 5 min, followed by a constant infusion of lidocaine (50 or 100 microg/kg/min, or saline, respectively). The halothane MAC was redetermined after a 60 min infusion of lidocaine or saline. The baseline halothane MAC for the control group was mean +/- s.d. 0.94 +/- 0.03%, and no significant decrease occurred following saline infusion. Lidocaine decreased halothane MAC in a dose-dependent fashion (r = 0.86; P < 0.0003). The results indicate that i.v. lidocaine may have a role in equine anaesthesia.     

Modulation of plasticity in human motor cortex after forearm ischemic nerve block

Deafferentation leads to cortical reorganization that may be functionally beneficial or maladaptive. Therefore, we were interested in learning whether it is possible to purposely modulate deafferentation-induced reorganization. Transient forearm deafferentation was induced by ischemic nerve block (INB) in healthy volunteers. The following five interventions were tested: INB alone; INB plus low-frequency (0.1 Hz) repetitive transcranial magnetic stimulation of the motor cortex ipsilateral to INB (INB+rTMSi); rTMSi alone; INB plus rTMS of the motor cortex contralateral to INB (INB+rTMSc); and rTMSc alone. Plastic changes in the motor cortex contralateral to deafferentation were probed with TMS, measuring motor threshold (MT), motor evoked-potential (MEP) size, and intracortical inhibition (ICI) and facilitation (ICF) to the biceps brachii muscle proximal to the level of deafferentation. INB alone induced a moderate increase in MEP size, which was significantly enhanced by INB+rTMSc but blocked by INB+rTMSi. INB alone had no effect on ICI or ICF, whereas INB+rTMSc reduced ICI and increased ICF, and conversely, INB+rTMSi deepened ICI and suppressed ICF. rTMSi and rTMSc alone were ineffective in changing any of these parameters. These findings indicate that the deafferented motor cortex becomes modifiable by inputs that are normally subthreshold for inducing changes in excitability. The deafferentation-induced plastic changes can be up-regulated by direct stimulation of the "plastic" cortex and likely via inhibitory projections down-regulated by stimulation of the opposite cortex. This modulation of cortical plasticity by noninvasive means might be used to facilitate plasticity when it is primarily beneficial or to suppress it when it is predominately maladaptive.     

Effect of capsaicin treatment or inferior alveolar nerve resection on dentine formation and calcitonin gene-related peptide- and substance P-immunoreactive nerve fibres in rat molar pulp

The aim of this study was to investigate whether decreased sensory innervation induced by capsaicin treatment or axotomy of the inferior alveolar nerve has an effect upon dentine formation in the rat first molar. Dentine formation was visualized by intravital injection of Procion brilliant Red H8BS and denervation was verified immunohistochemically for the neuropeptides calcitonin gene-related peptide (CGRP) and substance P. The observation times were 6 weeks for the capsaicin-treated group and 11 days for the axotomized group. Capsaicin injections caused a consistent reduction in numbers of CGRP- and substance P-immunoreactive fibres in the pulps and a somewhat smaller reduction in the periodontal tissues. Unilateral axotomy of the inferior alveolar nerve induced an almost complete loss of immunoreactive fibres in the pulp and in the mesial gingiva of the first molar. Dentine formation at the mesial pulp horn and at the central pulp floor was significantly reduced in both groups compared to controls. The results suggest that sensory neuropeptides such as CGRP and substance P may play a part in dentine formation.     

Gore-Tex tubing as a conduit for repair of lingual and inferior alveolar nerve continuity defects: a preliminary report

PURPOSE: This report describes the results of using a Gore-Tex (Gore Company, Flagstaff, AZ) tube as a conduit for repair of continuity defects in the inferior alveolar or lingual nerves. PATIENTS AND METHODS: Seven nerve repairs were performed in five patients (M:F = 1:4) with an age range of 16 to 56 years. The duration from injury to repair ranged from 4 to 30 months. Two inferior alveolar and five lingual nerves were repaired. RESULTS: All seven patients had anesthesia by objective testing preoperatively and had a continuity defect at the time of operation. The size of the defects ranged from 2 to 15 mm. Two of the seven patients had some return of sensation, occurring in defects of 3 mm or smaller. CONCLUSION: The results of this pilot study indicate that Gore-Tex tubing may not be effective in the repair of continuity defects except in those defects 3 mm or smaller, in which it may act as a protective barrier membrane rather than as a conduit.     

Pain in the lower extremities after subarachnoid block with lidocaine

Subarachnoid block is a widely practiced anesthetic technique. With the availability of small-diameter needles and the rises in out-patient surgery, the number of procedures performed with subarachnoid block and short-term local anesthesia have increased. We report two cases of bilateral pain in the lower extremities appearing 20-24 h after intradural anesthesia with 2% hyperbaric lidocaine. We analyze the factors that might have triggered this complication and compare the two patients with 14 others described in the literature. Three points in common were found: the use of hyperbaric lidocaine, administration of the agent through small gauge needles and the performance of out-patient surgery.     

Sciatic nerve palsy following uneventful sciatic nerve block

We describe the loss of function in the sciatic nerve after an uneventful sciatic nerve block using 25 ml of lignocaine 1% with adrenaline 1 in 200,000 in a patient receiving beta blocker drugs. Lack of pain on injection and complete regeneration of the nerve after 12 months in a patient with severe peripheral vascular disease led us to postulate ischaemic nerve damage as a mechanism of injury. Adrenaline-induced unopposed alpha-mediated vasoconstriction in a beta-blocked patient is suggested as a possible mechanism of peripheral nerve injury worthy of further investigation.