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At least 19 recordsLinked to original sources

Paresthesiae or no paresthesiae? Nerve lesions after axillary blocks.

Seeking paresthesiae when performing a peripheral nerve block may increase the risk of post-anesthetic neurological sequelae. To test this hypothesis, we prospectively followed two groups of patients who underwent hand surgery with an axillary block. In one group, the axillary plexus was located by actively seeking paresthesiae; in the other, pulsations of the axillary artery indicated an adequate position of the injection needle. Mepivacaine 10 mg/ml, with or without adrenaline, was used. The study included 533 patients, 290 in the paresthesia group and 243 in the artery group. Although unintentional, paresthesiae were elicited in 40% of patients in the artery group. Postanesthetic nerve lesions were seen in ten patients, eight in the paresthesia group and two in the artery group, all of whom had been blocked by mepivacaine with adrenaline. Symptoms varied between light paresthesiae lasting a few weeks, and severe paresthesiae, ache and paresis lasting more than 1 year. The etiology suspected was needle and perhaps injection trauma to the nerves during blocking. We conclude that whenever possible nerve blocks should be performed without searching for paresthesiae.

Adult↗

Risk factors for unpleasant paresthesiae induced by paresthesiae-producing deep brain stimulation.

Paresthesiae-producing deep brain stimulation (stimulation of ventrocaudal nucleus-VC, medial lemniscus-ML or internal capsule-IC) is one of the few procedures to treat the steady element of neural injury pain (NIP) currently available. Reviewing the first 60 patients with NIP submitted to deep brain stimulation (DBS) from 1978 to 1991 at the Division of Neurosurgery, Toronto Hospital, University of Toronto, we observed that 6 patients complained of unpleasant paresthesiae with paresthesiae-producing DBS, preventing permanent electrode implantation in all of them. Such patients accounted for 15% of the failures (6 out of 40 failures) in our series. In an attempt to improve patient selection, we reviewed our patients considering a number of parameters in order to determine risk factors for unpleasant paresthesiae elicited by paresthesiae-producing DBS. The results showed that this response happened only in patients with brain central pain complaining of evoked pain, secondary to a supratentorial lesion. Age, sex, duration of pain, quality of the steady pain, size of the causative lesion and site (VC,ML,IC) and type (micro or macroelectrode) of surgical exploration were not important factors. Unpleasant parethesiae in response to dorsal column stimulation, restricted thalamic lesion on computed tomography and the occurrence of associated intermittent pain were considered major risk factors in this subset of patients and the presence of cold allodynia or hyperpathia in isolation and the absence of sensory loss were considered minor risk factors. It is our hope that the criteria here established will improve patient selection and so, the overall results of DBS.

Adult↗

Interscalene brachial plexus block for shoulder surgery: a proximal paresthesia is effective.

This study was designed to determine whether the location of paresthesias is related to the success of interscalene blocks in providing anesthesia for shoulder surgery. Interscalene blocks were performed in 45 patients presenting for elective shoulder surgery. Interscalene injections of 33-55 mL of 1.5% mepivacaine with epinephrine were performed after the first elicited paresthesia to the shoulder, arm, forearm, or hand. In 20 patients (45%), the initial elicited paresthesia was to the shoulder, whereas in 25 patients (55%), the first paresthesia was reported as distal to the shoulder. All patients developed brachial plexus anesthesia adequate for shoulder surgery. The time-course of onset of motor block as evaluated at the shoulder and elbow was not different between patients with shoulder paresthesias and those with more distal paresthesias. Handgrip strength was quantitatively evaluated with a dynamometer, and both paresthesia groups showed similar decrements in hand strength except at the end of the measurement period, when patients with distal paresthesias had a significantly weaker handgrip than patients with shoulder paresthesias. We recommend that paresthesias to the shoulder be accepted in performing interscalene blocks for patients undergoing shoulder surgery.

Adult↗

Clinical evaluation of paresthesia steering with a new system for spinal cord stimulation.

OBJECTIVE: The goal was to evaluate, in a clinical study, the predicted performance of the transverse tripolar system for spinal cord stimulation, particularly the steering of paresthesia, paresthesia coverage, and the therapeutic range of stimulation. METHODS: Six transverse tripolar electrodes were implanted in the lower thoracic region in four patients experiencing chronic neuropathic pain. Electrode positions, relative to the spinal cord, were estimated from computed tomographic scans. A dual-channel stimulator was used for initial percutaneous tests, and an implanted single-channel stimulator was used for follow-up test sessions. Nine "balance" settings and several cathode-anode combinations were used with the dual-channel and single-channel stimulator, respectively. In each test, the increase of paresthesia coverage from the perception threshold to the discomfort threshold was registered on a body map and the corresponding voltages were recorded. RESULTS: Paresthesia steering occurred in all but one patient. The normalized steering score, enabling quantitative comparisons of paresthesia steering among tests and patients, showed that maximum paresthesia steering occurred when the electrode was at least 3 mm dorsal to the spinal cord and centered <2 mm from its midline. Paresthesia coverage included 70 to 100% of the body up to the electrode level, unless the electrode migrated or had broken wires. The therapeutic range, defined as the discomfort/perception of paresthesia threshold ratio, varied from 1.6 to 4.0. CONCLUSION: The clinical performance of transverse tripolar stimulation is in accordance with the characteristics predicted by computer modeling. It enables finer control of paresthesia than that achieved by polarity changes in conventional spinal cord stimulation systems.

Adult↗

Ischemic compression paresthesias in Guillain-Barré syndrome.

An experiment in nine patients tested the similarities and interactions between the paresthesias of Guillain-Barré syndrome (GBS) and tourniquet-induced compression paresthesias. During brachial compression, GBS paresthesias diminished in five of seven patients and new paresthesias occurred in two patients with purely motor GBS. Beginning 1 to 4 minutes after release of the cuff, all patients had new paresthesias, distinguishable from GBS symptoms. The novel finding was that GBS paresthesias diminished or ceased during the postcompression period in five of seven patients. Demyelinated peripheral nerves in GBS apparently can generate and transmit the spontaneous activity associated with paresthesias in the postcompression period. Interference occurs between the two types of paresthesias, possibly because both are caused by spontaneous ectopic activity in tactile nerves.

Foot↗

Inability to consistently elicit a motor response following sensory paresthesia during interscalene block administration.

BACKGROUND: Two methods of nerve block based on eliciting neural feedback with the block needle currently exist. The paresthesia technique uses sensory feedback to ascertain that the needle tip is close to the nerve. By contrast, a peripheral nerve stimulator makes use of motor responses to electrical stimulation. The relation of motor responses to an electrical peripheral nerve stimulator and sensory nerve contact (paresthesia) had not been studied. METHODS: Thirty consecutive unpremedicated patients who presented for shoulder surgery with interscalene block anesthesia were prospectively studied. Interscalene block was performed by the single paresthesia method of Winnie, using an insulated or non-insulated needle connected to a peripheral nerve stimulator with the power off. At the precise point of paresthesia, the peripheral nerve stimulator was turned on, and the current was slowly increased to 1.0 mA with a pulse width of 0.2 ms. Presence and location of any motor responses were observed and recorded. RESULTS: All patients had easily elicited paresthesias. The site of first paresthesia was to the shoulder in 73% of patients. Only 30% of patients exhibited any motor response to electrical stimulation up to 1.0 mA. There was no relation between site of paresthesia and associated motor nerve response. CONCLUSION: Elicitation of paresthesia does not translate to an ability to elicit a motor response to a peripheral nerve stimulator in the majority of patients.

Electric Stimulation↗

Backpacking-induced paresthesias.

OBJECTIVE: To evaluate the presence of numbness and paresthesias among long-distance backpackers on the Appalachian Trail. METHODS: Backpackers who hiked a minimum of 7 days were interviewed while hiking. Following their hike, a written questionnaire was mailed to the participants that explored the incidence of injuries and illnesses among hikers. Paresthesias were defined as either numbness or "phantom, burning, or shooting pains." A case-control analysis of risk factors for paresthesias was performed. RESULTS: Paresthesias were reported by 34% (96 of 280) of the backpackers completing the study. They included ulnar paresthesias (n = 4), meralgia paresthetica (n = 10), tarsal tunnel syndrome (n = 6), digitalgia paresthetica (n = 21), and nonspecific paresthesias (n = 61). The most common symptom was numbness: 81% (78 of 96). Significant risk factors included a distance of >2000 miles (relative risk [RR] = 1.3; 95% CI, 1.1-1.6; P = .01) and the duration of hiking (RR = 2.0; 95% CI, 1.2-3.2; P = .004) for the longest quartile. Nonsignificant factors included backpack weight, initial body weight, percentage of weight loss, running shoe usage, and multivitamin usage. Ninety-eight percent of the paresthesias (94 of 96) had resolved by the time of follow-up (median = 30 days). CONCLUSIONS: Paresthesias were a surprisingly common complaint among long-distance backpackers. Although they were distressing during backpacking, these neuropathies were self-limited and resolved after completion of hiking.

Adult↗

Area of paresthesia as determinant of sensory block in axillary brachial plexus block.

BACKGROUND AND OBJECTIVES: Paresthesia is widely considered a useful indicator for locating components of the brachial plexus using the axillary approach. While establishing axillary brachial plexus blocks, the authors attempted to correlate the area of paresthesia with the effectiveness of the sensory block. METHODS: Axillary brachial plexus blocks were established in 222 consecutive adult patients scheduled for elective surgery of the hand or forearm. After paresthesia was elicited in the distribution of one of the three terminal nerves of the hand (median, radial, or ulnar nerve), 30 microliters 1.5% mepivacaine without epinephrine was injected after advancing an indwelling catheter. Sensory block of each terminal nerve was assessed 20 minutes after the injection. RESULTS: The median and radial nerves were blocked with the highest reliability (87% and 93%, respectively) after paresthesia was elicited in the areas supplied by the corresponding nerves. The ulnar nerve was blocked most reliably ( > 85%) after the elicitation of paresthesia in its area of distribution as well as when no paresthesia was induced. The most reliable block of the musculocutaneous nerve (72%) was achieved after paresthesia was induced in the area supplied by the median nerve. CONCLUSION: Eliciting paresthesia at the nerve supplying the area of a planned surgical incision is a reliable determinant of successful axillary brachial plexus block.

Adult↗

Painful paresthesiae are infrequent during brachial plexus localization using low-current peripheral nerve stimulation.

BACKGROUND: Considerable controversy exists over the relationship of paresthesia to nerve stimulation. The purpose of this study was to determine the frequency with which patients report paresthesia at the point that an acceptable motor response is obtained to low-intensity current electrical stimulation. METHODS: Low-intensity current nerve stimulation (0.6 mA, 200 microseconds, 2 Hz) was used to identify the brachial plexus in 64 consecutive patients having shoulder or arm surgery with an interscalene block. During nerve localization and while maintaining a motor response (0.20 mA-0.40 mA), the patients were queried regarding any radiating sensation or pain (paresthesia) in the shoulder or extremity on the side of the blockade. Sensory distribution of the block, motor strength of the arm muscles, and adequacy of anesthesia were used to assess the extent of blockade. RESULTS: Ninety-five percent of patients had satisfactory surgical anesthesia. None of the patients spontaneously reported having a paresthesia during nerve stimulation. However, on careful questioning, half of the patients (55%) reported electrical paresthesia, defined as dull tingling sensation traveling down to their hands and coinciding with the motor response. In addition, most patients (71%) spontaneously reported having a mild, radiating paresthesia on initial injection of local anesthetic. CONCLUSIONS: Painful paresthesiae should be infrequent when a low-stimulating current is used to identify the neural components of the brachial plexus and when the block needle is advanced slowly. Low-current intensity nerve stimulation can be used to achieve successful interscalene block with minimal discomfort to the patient.

Adult↗

Increased perception of post-ischemic paresthesias in depressed subjects.

A psychophysical assessment of sensory activity linked to unmyelinated and myelinated primary afferents was conducted by estimating the intensity of thermal and tactile post-ischemic paresthesias in 11 nontreated depressed subjects (Zung's index > or =50) and 19 controls. Blood flow in the dominant forearm was arrested until ischemic pain tolerance was reached. Ischemic pain and post-ischemic paresthesias were numerically rated. The duration of blood flow occlusion to the time of ischemic pain tolerance was similar in both groups. Thermal (warm/cool) and tactile (tingling) paresthesias were 96% and 57% more intense in depressed than in control subjects, respectively. Zung's depression scores were positively correlated with the tingling and thermal paresthesias. Ischemic pain intensity correlated positively with thermal paresthesias. These findings suggest that depression is associated with enhanced sensory paresthesias that are known to be predominately linked to unmyelinated afferent activity.

Adult↗

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.

Bicuspid↗

Relationship between evoked motor response and sensory paresthesia in interscalene brachial plexus block.

BACKGROUND AND OBJECTIVES: This study sought to define the relationship between a paresthesia and a motor response (MR) to electrical nerve stimulation using a peripheral nerve stimulator (PNS) during interscalene block. We sought to determine if at a low amperage (< or =1.0 mA) a MR would precede a paresthesia. METHODS: Twenty-two interscalene blocks were performed using insulated needles and a PNS. A MR was obtained at 0.5 mA and then the PNS was turned off. The needle was further advanced until a paresthesia was elicited. The PNS was again turned on, the needle held immobile, and the amperage increased in 0.1 mA increments up to 0.5 mA, or an MR obtained, whichever occurred first. If no MR was obtained, the needle was withdrawn at 0.5 mA in the same direction as it entered until MR was again observed. RESULTS: A MR was obtained at 0.5 mA in all the patients. After the PNS was turned off and the needle further advanced, a paresthesia was elicited in 21 patients. When the PNS was turned on again, a MR was produced at 0 to 0.5 mA in 13 patients. In a subset of 8 patients without a second MR to stimulation up to 0.5 mA, the needle was withdrawn at that amperage. A MR was subsequently obtained during withdrawal in each patient in this subset. CONCLUSIONS: MR preceded paresthesia in every patient. The most likely explanation for this observation is that MR can be achieved at a small distance from the nerve, whereas elicitation of mechanical paresthesia requires either nerve contact or more intimate location of the needle's tip relative to the nerve. Another possible explanation is that motor fibers are located in a more superficial position and are therefore encountered first. Motor and sensory responses are separate and discrete phenomena.

Adult↗

Subclavian perivascular block: influence of location of paresthesia.

Subclavian perivascular block of the brachial plexus was used in 156 adult patients undergoing orthopedic hand and forearm surgery. The location of the elicited paresthesia prior to deposition of 30 ml of a solution containing 1% mepivacaine, 0.2% tetracaine and 1.200,000 epinephrine was recorded. Twenty minutes later the quality of the block in the distribution of the superior, middle and inferior trunks of the brachial plexus was evaluated. Anesthesia in each of the three trunks was compared with the three sites where the paresthesia was elicited (superior, middle, or inferior trunk). A middle trunk paresthesia was the most successful in producing surgical anesthesia of all three trunks. A superior trunk paresthesia was the paresthesia most often elicited. It resulted in a significantly lower incidence of inferior trunk anesthesia than did a middle or inferior trunk paresthesia. Complications included arterial puncture (25.6%), Horner's syndrome (64.1%), and recurrent laryngeal nerve block (1.3%), with no instances of symptomatic phrenic block or symptomatic pneumothorax.

Adult↗

A 21 year retrospective study of reports of paresthesia following local anesthetic administration.

A retrospective study of paresthesia following the injection of local anesthetic in dentistry was conducted by examining every report of paresthesia recorded by Ontario's Professional Liability Program from 1973 to 1993, inclusive. Only those cases where surgery was not conducted were considered in this study. The parameters examined included patient age and gender, needle gauge, site of injection, area affected, report of pain or any additional symptoms, and the type of local anesthetic used. From 1973 to 1993, there were 143 reports of paresthesia not associated with surgery. There were no significant differences found with respect to patient age, patient gender, or needle gauge. All reports involved anesthesia of the mandibular arch, with the tongue most frequently reported to be symptomatic, followed by the lip. Pain was reported in 22 per cent of the cases. Paresthesia was reported most often following the injection of articaine and prilocaine. In 1993 alone, there were 14 reports of paresthesia not associated with surgery. This can be projected to an incidence of 1:785,000 injections. Articaine was administered in 10 of these cases or prilocaine in the other four. The observed frequencies of paresthesia following the administration of articaine (p < 0.002) or prilocaine (p < 0.025) were significantly greater than the expected frequencies for these agents, based on the distribution of local anesthetic use in Ontario in 1993. These results are consistent with the suggestion that local anesthetic formulations may have the potential for mild neurotoxicity. Further studies are needed to investigate the mechanisms for this, and to determine whether similar findings would be found elsewhere.

Adult↗

Influence of lumbar spine pathology on the incidence of paresthesia during spinal anesthesia.

BACKGROUND AND OBJECTIVES: Paresthesia occasionally occurs during dural puncture or injection of local anesthetic for spinal anesthesia. Although the incidence of neurologic complications after spinal anesthesia is extremely low, the significance of paresthesia is unknown. The influence of known lumbar spine pathology on the incidence of paresthesia during spinal anesthesia is studied. METHODS: Incidence of paresthesia with dural puncture (PP) or injection (PI) was studied in two groups of patients. Group 1 included patients for elective total joint replacement without known spine pathology or complaints. Group 2 included patients for elective lumbar spine surgery who received spinal anesthesia. RESULTS: Significantly more PP (20% vs 9%) and PI (16% vs 6%) occurred in the spine surgery group. There were no neurologic sequelae of spinal anesthesia. CONCLUSIONS: This information suggests that the incidence of paresthesia during the conduct of spinal anesthesia is higher in patients with lumbar spine pathology. Although there were no neurologic complications, the sample size is too small to exclude an increase in the neurologic risk of spinal anesthesia in patients with known intraspinal pathology.

Adrenergic Agonists↗

Pyrethroid-induced paresthesia--a central or local toxic effect?

BACKGROUND: Pyrethroid-induced paresthesia is frequently seen after dermal exposure to pyrethroids. Affected individuals experience a sensation of burning, tingling, itching, or numbness, most commonly in the face. This occurs 1-2 hours after the beginning of exposure and resolves spontaneously. MECHANISMS: Paresthesia occurs as a result of a direct effect on intracutaneous nerve endings at very low pyrethroid doses. It is related to potency of the pyrethroid with pyrethroids without an alpha-cyano group generally showing the weakest effect. CONCLUSION: Doses sufficient to cause paresthesia are far lower than those causing central or systemic toxicity. Paresthesia is therefore considered to be a localized nuisance effect. The best advice to affected individuals is to prevent paresthesia from occurring through appropriate hygiene measures and personal protection.

Administration, Topical↗

Paresthesia associated with endodontic treatment of mandibular premolars.

The objective of this retrospective study was to determine how often paresthesia occurs and to examine the role of the anatomy of the inferior alveolar nerve (IAN). The study took the form of a review of the records of the endodontic department at the Creighton University School of Dentistry, a literature review, and cadaver dissections. The result showed that of 6313 teeth treated during a 7-yr period, 832 were mandibular premolar teeth. The eight reported cases of paresthesia in that group reflected an incidence of 0.96%. Observations of dissected human-cadaver mandibles indicated that the paresthesias of the mandible could be related to the confinement of the IAN within the limits of the mandible. It was concluded that these paresthesias were related to the intrabony course of the IAN through the mandible, which contributed to the paresthesia symptoms.

Adult↗