Anatomical study of the dorsal cutaneous branch of the ulnar nerve using ultrasound.

OBJECTIVES: To determine whether ultrasound allows precise assessment of the course and relations of the dorsal cutaneous branch of the ulnar nerve (DCBUN). METHODS: This work, initially undertaken in cadavers, was followed by high-resolution ultrasound study in 20 healthy adult volunteers (40 nerves) by two musculoskeletal radiologists in consensus. Location and course of the DCBUN and its relations to adjacent anatomical structures were analysed. RESULTS: The DCBUN was consistently identified along its entire course by ultrasound. Mean cross-sectional area of the nerve was 1.6 mm(2) (range 1.1-2.2). The level at which the DCBUN branches from the ulnar nerve was located a mean of 57 mm (range 40-80) proximal to the ulnar styloid process and 11 mm (range 7-15) radial to the medial border of the ulna. The DCBUN then crossed the medial border of the ulna a mean of 14 mm (range 6-25) proximal to the ulnar styloid process. CONCLUSION: The DCBUN is clearly depicted by ultrasound. Precise mapping of its anatomical course could have significant clinical applications, such as preventing injury during surgery of the ulnar side of the wrist or helping in the diagnosis of chronic pain of the ulnar side of the hand. KEY POINTS: • The dorsal cutaneous branch of the ulnar nerve (DCBUN) is often injured. • The DCBUN originates from the ulnar nerve in the distal third of the forearm. • It can be clearly depicted by ultrasound. • The level at which the DCBUN crosses the ulna is variable. • Precise mapping of its anatomical course could have significant clinical applications.

Preoperative skin marking and perioperative checks require careful thought: a report of a near miss.

A patient marked preoperatively for ulnar nerve decompression under general anaesthesia was found to have symmetrical operative site markings. The correct skin mark was transferred to the other side by her sleeping position the night before surgery. Skin marking is an adjunct to safe surgery but is not failsafe.

Accuracy of Carpal Tunnel Injection: A Prospective Evaluation of 756 Patients.

Background: Corticosteroid injection into the carpal tunnel is both a diagnostic test and a therapeutic modality in the treatment of carpal tunnel syndrome. Many injection techniques are described in the literature. Improper placement of injection may result in damage to neurovascular structures in the carpal canal or decrease efficacy of the test and/or therapy. The purpose of this study is to determine if carpal tunnel injection using anatomic landmarks is reproducible and safe. A review of the senior author's injection technique is presented. Methods: Over 8 years, there were 756 attempted placements of a 25-gauge needle into the carpal tunnel in a simulated carpal tunnel injection prior to open carpal tunnel release. The needle was inserted at the wrist crease, just ulnar to palmaris longus. Open carpal tunnel release was subsequently performed, and position of the needle was recorded. Results: In 572 patients (75.7%), the needle was found to be in the carpal tunnel without penetration of contents. The needle was in the carpal tunnel but piercing the median nerve in 66 attempts (8.7%). The carpal tunnel was missed in 118 attempts (15.6%). Conclusions: This is the largest study looking at accuracy of carpal tunnel injection using anatomic landmarks. Our injection accuracy (75.7%) is less than reported in previous studies, which note 82% to 100% accuracy using the same injection technique. This may indicate that carpal tunnel injection is less reliable than previously thought. Safety of carpal tunnel injection remains an important concern. The median nerve was penetrated in 8.7% of attempts.

Superficial surgical landmarks for identifying the posterior interosseous nerve.

OBJECT: There is a paucity of information in the neurosurgical literature regarding the surgical anatomy surrounding the posterior interosseous nerve (PIN). The goal of the current study was to provide easily recognizable superficial bone landmarks for identification of the PIN. METHODS: Thirty-four cadaveric upper extremities obtained from adults were subjected to dissection of the PINs, and measurements were made between this nerve and surrounding superficial bone landmarks. In all specimens the main radial trunk was found to branch into its superficial branch and PIN at the level of the lateral epicondyle of the humerus. Proximally, the PIN was best identified following dissection between the brachioradialis and extensor carpi radialis longus and brevis muscles. At its exit site from the supinator muscle, the PIN was best identified after retraction between the extensor carpi radialis longus and brevis and extensor digitorum communis muscles. This site was a mean distance of 6 cm distal to the lateral epicondyle of the humerus. No compression of the PIN by the tendon of origin of the extensor carpi radialis brevis muscle was seen. One specimen was found to have a proximally split PIN that provided a previously undefined articular branch to the elbow joint. The mean diameter of the PIN proximal to the supinator muscle was 4.5 mm. The leash of Henry crossed the PIN in all but one specimen and was found at a mean distance of 5 cm inferior to the lateral epicondyle. The PIN exited the distal edge of the supinator muscle at a mean distance of 12 cm distal to the lateral epicondyle of the humerus. Here the mean diameter of the PIN was 4 mm. The exit site from the distal edge of the supinator was found to be at a mean distance of 18 cm proximal to the styloid process of the ulna. This exit site for the PIN was best identified following dissection between the extensor carpi radialis longus and brevis and extensor digitorum communis muscles. The distal articular branch of the PIN was found to have a mean length of 13 cm and the proximal portion of this terminal segment was located at a mean distance of 7.5 cm proximal to the Lister tubercle. CONCLUSIONS: The addition of more anatomical landmarks can help the neurosurgeon to be more precise in identifying the PIN and in avoiding complications during surgery in this region.

Variant location of the musculocutaneous nerve during axillary nerve block.

We present the case of a 56-year-old man who underwent axillary nerve block for a wrist arthroscopy procedure, with real-time ultrasound and peripheral nerve stimulator guidance. The ulnar nerve and radial nerve were located medial and posterior to the brachial artery, respectively. A large complex structure was noted in the position typically occupied by the median nerve. Contact of this structure with the stimulating needle produced strong biceps contraction, and slight adjustment of the needle resulted in forearm pronation. After injection of 10 mL of local anesthetic near this structure, it appeared to consist of two separate components on ultrasound. We believe that these components represented the median and musculocutaneous nerves lying together, lateral to the artery. Radial, median, ulnar, and musculocutaneous nerve block ensued, and wrist arthroscopy was carried out uneventfully. Knowledge of this anatomical variation may improve anesthesiologists' ability to provide effective axillary block.

Ulnar nerve lesion at the wrist and sport: A report of 8 cases compared with 45 non-sport cases.

OBJECTIVE: Reporting clinical and electrodiagnostic characteristics of sport-related ulnar neuropathies at the wrist. PATIENTS AND METHODS: Eight sport-related and 45 non-sport-related cases from 53 ulnar neuropathies at the wrist cases over 14 years. RESULTS: Sport-related ulnar neuropathies at the wrist cases were due to cycling (5 cases), kayaking (2 cases), and big-game fishing (1 case). No patient had sensory complaints in ulnar digits, and all had motor impairment. Conduction across the wrist with recording on the first dorsal interosseous muscle was impaired in all cases, with conduction block in 5. Two cyclists showed bilateral ulnar neuropathies at the wrist. All cases recovered within 2 to 6 months with sport discontinuation. Distal lesions of the deep motor branch were more frequent in sport- than non-sport-related cases. CONCLUSIONS: The 8 sport-related ulnar neuropathies at the wrist cases involved the deep motor branch. Conduction study to the first dorsal interosseous muscle across the wrist is the key to electrodiagnostics. Bilateral cases in cyclists does not require wrist imaging.

The posterior interosseous nerve and the posterolateral approach to the proximal radius.

We dissected 21 cadaver elbows to determine the relationship of the posterior interosseous nerve to the posterolateral approach to the elbow and head of the radius. At the distal end of the exposure the first branches at risk, those to extensor carpi ulnaris, were on average 6.0 +/- 1.0 cm (4.0 to 8.4) from the articular surface of the radial head. When using the posterolateral approach it is important that the interval between extensor carpi ulnaris and anconeus is clearly identified with the forearm fully pronated. The supinator should be released close to its ulnar border. It is safe to expose the proximal radius as far as the distal aspect of the bicipital tuberosity.

The use of a volar ulnar portal in wrist arthroscopy.

PURPOSE: The purpose of this study was to quantitatively describe the neurovascular relationships of a volar ulnar (VU) wrist arthroscopy portal. A second purpose was to evaluate whether the use of a VU portal identified additional pathology of the lunotriquetral ligament and ulnar sling mechanism that was not seen through the dorsal portals. TYPE OF STUDY: This study was an anatomic study and retrospective chart review. METHODS: Cadaver dissections established the neurovascular anatomy of the VU portal. Measurements were taken from the portal to the ulnar nerve and artery, the palmar cutaneous branch of the ulnar nerve, and the pronator quadratus. A dorsal capsulotomy was performed to assess the ligamentous interval. A chart review was performed of 23 patients in whom a volar ulnar portal was used. Intraoperative pathology that was identified through the VU portal but was not visible through a dorsal portal was recorded. Postoperative neurovascular complications were noted. RESULTS: The portal was generally > 5 mm radial to the ulnar neurovascular bundle, but no true internervous plane was seen. Tears of the palmar aspect of the lunotriquetral ligament were seen in 7 patients. One patient had a triangular fibrocartilage tear that extended into the dorsal radioulnar ligament. CONCLUSIONS: This study provides a safe, standardized approach to the volar ulnar aspects of the radiocarpal joint, which is useful for evaluation of the ulnar sling mechanism and the dorsal radioulnar ligament. The VU portal aids in the diagnosis and debridement of tears involving the palmar aspect of the lunotriquetral ligament. The VU portal should be considered for inclusion in the arthroscopic examination of any patient with ulnar sided wrist pain. LEVEL OF EVIDENCE: Level IV.

Anatomic considerations in evaluation of the proximal ulnar nerve.

Knowledge of general ulnar anatomy aids in the understanding of the possible site of ulnar nerve entrapment and the rationale for differential diagnosis possibilities. Understanding of internal nerve topography sheds light on reasons for ulnar nerve susceptibility at the elbow region and offers an explanation for the sparing of forearm muscles in ulnar neuropathy at the elbow. Dynamic anatomy or biomechanics of the elbow help elucidate the pathophysiology of ulnar nerve compression at the elbow. The anatomy interface with electrodiagnosis illustrates rationale for particular methods employed and particular tests used in evaluating the ulnar nerve. Electrodiagnostic testing enhances localization of ulnar nerve lesions, excludes other causes in the differential diagnosis, and may aid with surgical selection.

The immediate effects of tension of counterforce forearm brace on neuromuscular performance of wrist extensor muscles in subjects with lateral humeral epicondylosis.

STUDY DESIGN: Within-subject repeated-measures study. OBJECTIVES: To examine the immediate effects of counterforce forearm brace on isokinetic strenght stretch reflex, passive stretching pain threshold of the wrist extensors, and proprioception of the wrist in subjects with lateral humeral epicondylosis for different strap tensions of a forearm brace. BACKGROUND: Counterforce forearm bracing has been used for treating lateral humeral epicondylosis, but the effect of brace tension has not been well reported. METHODS AND MEASURES: Fifteen subjects diagnosed with lateral humeral epicondylosis on their dominant arm were tested under 4 randomized conditions: (1) no brace, (2) brace with minimal tension, (3) brace with 25-N tension, and (4) brace with 50-N tension. The tests included isokinetic wrist extensors strength, passive stretching force in wrist flexion to elicit pain in the wrist extensors, wrist proprioception, and stretch reflex latency of the extensor carpi ulnari. A repeated-measures MANOVA was used to analyze the data and significant results were further analyzed with post hoc linear contrasts (alpha = .05). RESULTS: Among the 4 conditions, significant differences were found in wrist proprioception P = .032) and pain threshold to passive stretching of the wrist extensors (P = .05), but were not found in wrist extension isokinetic strength and stretch reflex latency of the extensor carpi ulnaris. CONCLUSION: A forearm counterforce brace, as applied in this study, affects wrist joint proprioception and increases the pain threshold to passive stretching of the wrist extensors in subjects with lateral humeral epicondylosis, but it has no effect on wrist extensor strength and stretch reflex latency of the extensor carpi ulnaris.

Pediatric throwing injuries about the elbow.

Pediatric elbow injuries that result from repetitive throwing-type activities are common. These injuries differ from those seen in adults, because of anatomic differences. The purpose of this paper is twofold: first, to review the anatomy of the elbow and the mechanics of the throwing motion about the elbow, and second, to discuss the diagnosis, treatment, rehabilitation, and prevention of pediatric throwing injuries of the elbow.

Ulnar mononeuropathy associated with eosinophilia.

A boy aged 4.5 years presented with isolated left ulnar nerve motor neuropathy and moderate eosinophilia. There was no evidence of parasitic infection. He was commenced on empirical diethylcarbamazine citrate and albendazole. Improvement occurred 6 days later with complete recovery by 2 weeks. It is presumed that he had a parasitic infection.

Comparison of ultrasonically activated scalpel and traditional technique in radial artery harvesting: clinical research.

BACKGROUND: Use of the radial artery (RA) as a conduit in coronary artery bypass grafting (CABG) has become increasingly popular in recent years. The aim of this study was to compare the results of two different RA harvesting techniques. Use of the harmonic scalpel is suggested to be safe and additionally reduces spasm rates. MATERIAL AND METHODS: From January 2000, the first 200 consecutive patients who underwent RA harvesting for CABG were enrolled in this study. Patients were divided into two groups. RA was harvested by means of electrocautery + hemoclips in Group I and by harmonic scalpel + hemoclips in Group II. 30 patients (30 %) in Group I and 25 patients (25 %) in Group II were female. Mean age was 53.9 +/- 9.3 and 53.5 +/- 8.4 years in Group I and Group II, respectively. Hand circulation and ulnar collateral flow was assured with a modified Allen test in all patients preoperatively. During the operation perfusion of the hand was monitored by oximetric plethysmography. The distal end of RA was also explored and clamped with a soft vascular clamp to evaluate the saturation values in the groups. During the clamping period, oxygen saturation values did not decrease so we harvested RAs in all patients. RESULTS: There were no statistically significant differences between the groups with the exception of the RA harvesting times, the postoperative analgesia requirements, the rate of vasospasm and the need for hemostatic clips. CONCLUSION: Harmonic scalpel usage in RA harvesting causes less trauma to adjacent tissues; the analgesia requirements, the rate of vasospasm, the RA harvesting time and the need of hemostatic clips decreases. We conclude that the use of a harmonic scalpel for radial artery harvesting is safer and faster than the routine technique.

Anterior interosseous nerve paralysis: cubital tunnel (Kiloh-Nevin) syndrome.

Paralysis of the anterior interosseous nerve may occur for a variety of reasons. It has been suggested that such a malady presents clinically more often than is recognized. Some authors attribute this to a general misunderstanding or ignorance of the precise anatomical distribution and motor function of this branch of the median nerve. The neuropathy produces a clinical scenario with a characteristic disturbance of the "pinch grip." Spontaneous recovery has been reported, but is said to be delayed and incomplete. Surgical exploration of the nerve may reveal a biomechanical basis for irritation, and decompression maneuvers may result in rapid and complete recovery. It is important to recognize, however, the value of conservative measures, including mobilization and adjustive procedures, which may be specifically directed to the elbow joint and other regions of the upper extremity. Such techniques may assist in reducing restrictive influences comprising the nerve and associated tissues. The benefits of electrotherapy may prove invaluable and, perhaps, should be considered prior to more radical procedures. Therefore, the practitioner should be wary of the potential to approach such a condition from the chiropractic perspective of treatment and management, which may yield rewarding sequellae.