Ulnar nerve

Ulnar nerve—monitor response of the adductor pollicis (thumb)... 

There is suggestive evidence indicating that the changes in NCV associated with lead exposure may be transient. Muijser et al. (1987) investigated the effects of a 5-month exposure to lead during the demolition of a steel structure coated with lead-based paints. The motor and sensory nerve conduction velocities were measured in the median and ulnar nerves of eight exposed workers and compared with unexposed referents as well as themselves at 3 and 15 months after the termination of exposure. The mean PbB levels in the exposed workers were 82.5 18.9 pg/dL at the termination of exposure,... 

One of the most sensitive systems affected by lead exposure is the nervous system. Encephalopathy is characterized by symptoms such as coma, seizures, ataxia, apathy, bizarre behavior, and incoordination (CDC 1985). Children are more sensitive to neurological changes. In children, encephalopathy has been associated with PbB levels as low as 70 pg/dL (CDC 1985). The most sensitive peripheral index of neurotoxicity of lead is reported to be slowed conduction in small motor libers of the ulnar nerve in workers with 30-40 pg/dL lead in blood (Landrigan 1989). Other potential biomarkers of lead suggested for neurotoxicity in workers are neurological and behavioral tests, as well as cognitive and visual sensory function tests (Williamson and Teo 1986). However, these tests are not specific to elevated lead exposure... 

A decrease in the amplitude of the sensory nerve action potential has also been observed in a group of 20 asymptomatic workers exposed to -hexanc (Pastore et al. 1994). The subjects of this study were selected on the basis of urinary levels of the n-hexane metabolite 2,5-hexanedione (See Sections 2.3 and 2.7) exceeding 5 mg/L and compared to a group of unexposed laboratory workers. Mean years worked was 8.13 (range, 1.5—23 years). Sensory and motor nerve conduction velocities and distal latencies were normal in all nerves tested. However, significant decreases were found in sensory nerve action potential amplitude in the median, sural, and ulnar nerves. Neither the level of 2,5-hexanedione in urine nor age correlated with the changes in amplitude however, there was a significant correlation between years worked and amplitude. 

Animals continually exposed to concentrations between 100 and 600 ppm developed signs of peripheral neuropathy after 4-8 weeks in cats, the conduction velocity of the ulnar nerve was less than one-half of normal after exposure for 7-9 weeks. In these animals, histologic examination revealed focal denudation of myelin from nerve fibers with or without axonal swelling. In rats and monkeys, adverse effects on neurophysiological indicators of nervous system integrity were found with 9-month exposures to 100 ppm, 6 hours/day, 5 days/week. MBK neuropathies, however, occurred only after 4-month exposure at 1000 ppm. Four months of intermittent respiratory exposure of rats to 13 00 ppm caused severe symmetric weakness in the hind limbs. ... 

In a 10-month study, monkeys exposed to 1,000 ppm 2-hexanone had abnormal results in electrodiagnostic tests (Johnson et al. 1977). There was a progressive and statistically significant decrease in the maximum motor conduction velocity of the sciatic-tibial nerves starting at 4 months of exposure and a decrease in the maximum conduction velocity of the ulnar nerves starting at 1 month. Decreased amplitude of evoked muscle action potential was also seen at 1,000 ppm. 

Results of 100 ppm exposure were similar to those of controls except for a statistically significant decreased response in the ulnar nerve at the 1 and 3 month measurements and in the sciatic-tibial nerve only at 9 and 10 months. Recovery to pre-exposure values for motor-conduction velocities took 2 months for the 100 ppm group and 6 months for the 1,000 ppm group. 

Efforts should be made to use these drugs sparingly, and to check that their effects have worn off before the patient leaves the operating room. In fact, electric stimulation of a peripheral nerve (e.g., ulnar nerve) can be used to objectively determine if there is residual muscle paralysis.1 The muscles supplied by the nerve must show an appropriate twitch response to a given electric stimulus to insure that the patient has recovered adequately from the neuromuscular blocking drug.20,31... 

Assessment of neuromuscular block usually is performed by stimulation of the ulnar nerve. Responses are monitored from compound action potentials or muscle tension developed in the adductor pollicis (thumb) muscle. Responses to repetitive or tetanic stimuli are most useful for evaluation of blockade of transmission. Thus, stimulus schedules such as the train of four and the double burst or responses to tetanic stimulation are preferred procedures. Rates of onset of blockade and recovery are more rapid in the airway musculature (jaw, larynx, and diaphragm) than in the thumb. Hence, tracheal intubation can be performed before onset of complete block at the adductor pollicis, whereas partial recovery of function of this muscle allows sufficient recovery of respiration for extubation. 

The strain index has not been developed to predict increased risk for distal upper-extremity disorders to uncertain etiology or relationship to work. Examples include ganglion cysts, osteoarthritis, avascular necrosis of carpal bones, and ulnar nerve entrapment at the elbow. 

An example method of recording the ENG involves stimulation of the ulnar nerve on the upper forearm under the bicep. This stimulation produces a twitching of the muscles in the fingers. The ENG is detected as the efferent action potential passes two biopotential electrodes straddling the nerve at the wrist. Figure 17.46 shows the placement of electrodes and an illustration of the propagation delay in the ENG waveform. 

Flexor pronator (medial) group Supplied by the median and ulnar nerves, this group comprises of the pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, and the flexor digito-rum superficialis. 

Occasionally, the ulnar nerve maybe drawn from its normal position in the ulnar groove and become entrapped in the joint. 

With Rang types III and IV, open reduction is required when the apophysis has become entrapped in the elbow joint following a dislocation (Fig. 18.16). Intra-articular fragments may be washed out and the ulnar nerve explored. In the case of elbow dislocation, if following reduction, the epicondyle is... 

The surgical incision is made along the medial supracondylar ridge. The ulnar nerve is located and protected. Care is taken to limit excessive soft tissue stripping to avoid vascular injury to the trochlea ossific nucleus. The elbow is immobilised at 90° of flexion with the forearm in neutral. 

Leet AI, Young C, Hoffer MM (2002) Medial condyle fractures of the humerus in children. J Pediatr Orthop 22 2-7 Lyons JP, Edwin A, Hoffer MM (1998) Ulnar nerve palsies after percutaneous cross-pinning of supracondylar fractures in children s elbows. J Pediatr Orthop 18 43-45 Lyons ST, Quinn M, Stanitski CL (2000) Neurovascular injuries in type III humeral supracondylar fractures in children. Clin Orthop 376 62-67... 

Millesi, H. Meissl, G. Berger, A The interfascicular nerve-grafting of the median and ulnar nerves. J. Bone and Joint Surgery 1972,54A, 727. 

Cubital Tunnel Syndrome is compression of the ulnar nerve in the elbow, thought to be caused by resting the elbow on a hard surface or sharp edge. Symptoms include tingling in the ring finger and little finger. 

Meperidine reversibly blocks voltage-gated Na currents with a half-maximum inhibiting concentration (ICjg) of 112 pM. Clinically, meperidine shows a dose-dependent blockade of both the sensory and motor fibers of the ulnar nerve after infiltration. Two percent meperidine blocks both sensory and motor activity at the hypothenar muscle. Intrathecal doses of meperidine 50 mg can provide short-duration spinal anesthesia. 

Leprosy A 58-year-old man with ankylosing spondylitis, receiving infliximab, developed multiple plaques on the face, chest, and limbs, a thickened, tender ulnar nerve, and severe neuritis of the feet biopsy showed lepromatous Hansen s disease [133 ]. In this case the use of infliximab may have resulted in either a new infection or reactivation of a latent infection with Mycobacterium leprae. 

The Musculoskeletal disorders more commonly seen in dental surgeons are Carpal Tunnel Syndrome Ulnar Nerve Entrapment Pronator Syndrome Tendinitis Tenosynovitis Extensor Wad Strain Thoracic Outlet Syndrome Rotator Cuff Tendonitis (Nield-Gehrig, 2008). 

Somatic dysfunctions can involve contraction of the related muscles, compression of the neural elements, strain of the ligamentous aspects, and restriction primarily of the secondary motions of the joint components. The radial head typically entails posterior or anterior dysfunctions and may involve the muscles, the annular ligament, and the lateral collateral ligament. The humero-olecranon dysfunctions can involve the muscles, the medial collateral ligament, and can be related to symptoms involving the ulnar nerve. Restriction of elbow... 

The ulnar nerve may be palpated in the groove between the medial epicondyle and the... 

Tinel test This is performed by tapping over the ulnar nerve as it passes between the olecranon and medial epicondyl. Marked sensitivity may be indicative of a neuroma or inflammation of the ulnar nerve. 

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