AAEM minimonograph #43: Neuromuscular problems in the performing arts

Over the past 10–15 years, there has been increasing interest in the health problems of performing artists. In this review, I will discuss the major playing-related disorders seen in instrumental musicians. Among the 672 instrumentalists evaluated, the major diagnoses identified included musculoskeletal disorders in 64%, peripheral nerve problems in 22.5%. and focal dystonia in 7%. Sixty percent of instrumentalists were female although males predominate in the group with focal dystonia. The average age of those evaluated was 32 years. Among musculoskeletal disorders overuse syndrome is the most common. Frequent peripheral nerve disorders include thoracic outlet syndrome, carpal tunnel syndrome, and ulnar neuropathy. A characteristic distribution of symptoms and signs is identified for each instrument group. Electrodiagnostic studies are an important part of the evaluation of these disorders. With carefully designed treatment, the majority of instrumental musicians can be returned to full and pain-free playing activities. The success rate is highest in some entrapment neuropathies but remains low in focal dystonia. © 1994 John Wiley & Sons, Inc.     

Uveal effusion syndrome complicated by anterior ischemic optic neuropathy

We report on a case of idiopathic uveal effusion syndrome complicated by AION. To our knowledge such an association hasn't been previously described. We suggest that scleral thickening caused obstruction of vortex veins followed by uveal effusion and compression of posterior ciliary arteries within their intrascleral tract, leading to AION. Nevertheless it can't be excluded that AION was the result of mechanical compression on ciliary vessels of optic disc by choroidal detachment.     

Correlations between nerve function and tissue oxygenation in diabetic patients: further clues to the aetiology of diabetic neuropathy?

Summary Transcutaneous oxygen, laser Doppler flowmetry, peroneal nerve motor conduction velocity and skin temperature were assessed in both legs of 34 diabetic patients, who had a mean age of 41 (range 29–77) years, and diabetes duration of 21 (3–34) years. Transcutaneous oxygen significantly correlated with peroneal nerve motor conduction velocity (r=0.59 p<0.001) and laser Doppler flowmetry (r=0.7 p<0.001). Laser Doppler flowmetry correlated weakly with peroneal motor conduction velocity, (r=0.34 p<0.05). In each patient the leg with the higher transcutaneous oxygen (mean 70.2±9.3 (SD) mmHg) had a significantly higher peroneal motor conduction velocity (45.3±7.1 vs 41.5± 6.3 m/s, p<0.01), than the leg with the lower transcutaneous oxygen (61.0±11.9 mm Hg), though no difference in skin temperature was observed, 31.4±0.4 vs 31.1±0.5°C. We then assessed the potential for reversibility of conduction velocity deficits in ten non-diabetic patients, aged 59 (52–77) years, undergoing unilateral femoro-popliteal bypass, measuring transcutaneous oxygen, peroneal nerve motor conduction velocity and skin temperature pre- and 6 weeks post-surgery. In the control leg (unoperated) there was no significant change in transcutaneous oxygen (63.2±8.8 vs 63.0±4.6 mm Hg), peroneal nerve motor conduction velocity (45.1±7.8 vs 43.4±7.2 m/s) or skin temperature (30.8±1.3 vs 30.2±1.2°C) after surgery (all NS). In the operated leg, transcutaneous oxygen increased from 59.3±10.7 to 70.7±7.2 mm Hg (p<0.01), and peroneal nerve motor conduction velocity from 42.6±6.1 to 46.7±3.2 m/s (p<0.01), but skin temperature was unchanged 30.3±0.4 vs 30.4± 1.3°C (NS). These studies provide further evidence that peripheral nerve function is associated with tissue hypoxia and that improving tissue oxygenation can significantly improve nerve conduction over a short period of time.     

RESULTS OF OPEN CARPAL TUNNEL RELEASE: A COMPREHENSIVE,RETROSPECTIVE STUDY OF 188 HANDS

Background : Many recent reports of the results of decompression of the median nerve in the carpal tunnel have concentrated on only one aspect of recovery (numbness, grip etc.), and there are no reports of a comprehensive study of outcome. The aim of the present study was to review comprehensively the results of the direct visualization method of decompression of the carpal tunnel and to compare them with the published results of endoscopic release. Methods : Patients' perceptions of the severity of pain, numbness and paraesthesiae due to carpal tunnel syndrome (CTS), before and after open carpal tunnel release (CTR) in 188 hands were reviewed retrospectively at a minimum time of follow-up of 18 months. Motor and sensory testing, provocation testing and measurement of scar tenderness in 135 hands were performed at a clinical review. Results : Subjective results showed that 70% experienced a reduction in the severity of pain after CTR, 78% of hands experienced a reduction in the severity of paraesthesiae and 77% experienced a reduction in the severity of numbness. A total of 49% had improvements in all three symptoms after CTR. At the clinical review, sensory testing revealed that 59% of hands had normal or slightly diminished light touch, 35% had normal static two-point discrimination and 61% had normal dynamic two-point discrimination. Results for Tinel's test, Phalen's test and pressure provocation testing were positive in 10% of hands. There was no scar tenderness in 38%, no persisting thenar atrophy in 90%. Normal grip strength was found in 93% and 91% had normal pinch strength. Conclusions : It was concluded that open carpal tunnel release remains a safe and reliable treatment for carpal tunnel syndrome. The very low incidence of serious complications from the open technique of CTR, when compared with endoscopic CTR as published by different authors in the literature, and the comparable clinical results, appears to make the open technique a safer and preferable option. However, a properly controlled trial of both techniques is necessary to compare them.     

背根神经节Nav1.8磷酸化在大鼠糖尿病痛性周围神经病变中的作用

目的 本研究采用射频热凝毁损腰交感神经节,探讨背根神经节（DRG）Nav1．8磷酸化在大鼠糖尿病痛性周围神经病变中的作用。方法 采用腹腔注射链尿佐菌素诱导糖尿病痛性周围神经病变大鼠模型,取造模成功的大鼠20只,随机分为糖尿病对照组（D组）及交感神经节射频热凝组（R组）,每组10只,另取10只同月龄大鼠为正常对照组（C组）。R组大鼠在X光机介导下行右侧L3,4椎旁腰交感神经节射频热凝毁损。分别于射频热凝前、射频热凝后1、2周时,采用von Frey纤维丝测定大鼠右侧后爪对机械性刺激缩足反应的阈值（PWT）;射频热凝后2周,采用Western-blotting方法测定DRG细胞Nav1．8蛋白和苏氨酸磷酸化Nav1．8蛋白表达,并采用透射电镜观察大鼠腓肠神经超微病理结构。结果 与C组比较,射频热凝前D组和R组PWT降低（P＜0．01）。射频热凝后1～2周,R组较D组PWT升高,但仍较C组降低（P＜0．05）。C组髓鞘排列均匀,轴突内可见形态正常的线粒体;D组脱髓鞘明显,髓鞘板层排列紊乱、断裂、肿胀;R组脱髓鞘程度明显减轻,髓鞘板层局部排列紊乱、空泡形成。与C组比较,D组和R组Nav1．8蛋白表达降低（P＜0．05）,而苏氨酸磷酸化Nav1．8蛋白表达增高（P＜0．01）;R组苏氨酸磷酸化Nav1．8蛋白表达低于D组（P＜0．05）。结论 DRG细胞Nav1．8的磷酸化可能是糖尿病痛性周围神经病变大鼠痛觉过敏形成的机制之一。     

The Toxic Effects of Serum from Patients with Type 1 Diabetes Mellitus on Mouse Neuroblastoma Cells: A New Mechanism for Development of Diabetic Autonomic Neuropathy

The pathogenesis of diabetic neuropathy is incompletely understood. The possibility that humoral neurotoxic factors contribute as a cause of diabetic neuropathy was tested by application of serum from patients with Type 1 and Type 2 diabetes to mouse neuroblastoma cells, which have the characteristics of adrenergic neurons in culture. Serum from patients with Type 1 diabetes and somatic neuropathy significantly inhibited both proliferation and differentiation of neuroblastoma cells, while serum from patients with Type 1 diabetes but no symptoms of neuropathy and patients with Type 2 diabetes and neuropathy had no effect on proliferation, and serum from Type 2 patients only marginally inhibited differentiation. The effects of Type 1 diabetic serum could be reversed by pre-absorption of the serum to neuroblastoma cells, and were independent of glucose levels. Immunoglobulins precipitated from the sera mimicked the effects of whole sera. These results suggest that Type 1 diabetes mellitus causes a change in serum composition, possibly related to autoimmunity, that is capable of contributing to adrenergic autonomic neuropathy in diabetic patients.     

Abnormal Digital Pressure Measurements in Diabetic Neuropathic Foot Ulceration

The diabetic neuropathic ulcer is typically slow to heal and recurrent. Macrovascular insufficiency is usually excluded as foot pulses are present and ankle:brachial pressure ratios are not decreased. These assessments cannot however exclude more distal vascular disease. Digital pressure measurements enable a reliable assessment of the distal peripheral vascular status to be made. The aim of this study was therefore to use toe pressures to assess the contribution of distal ischaemia in the pathogenesis of the neuropathic ulcer. Sixteen diabetic patients with recurrent neuropathic foot ulceration had their toe pressures compared to 10 neuropathic patients without a history of foot ulceration, 10 diabetic control subjects, and 11 normal subjects. Four non-diabetic patients with neuropathy and foot ulceration were also assessed. All subjects had ankle:brachial pressure indices ≧ 1. Toe pressure was assessed using laser Doppler flowmetry to record the return of skin blood flow. The toe:brachial pressure index (TBI) was then calculated. The diabetic patients with a history of recurrent neuropathic ulceration, had the lowest mean TBI, 0.63 ± 0.14 (SD), compared to the non-ulcerated diabetic neuropathy patients, the diabetic control subjects, and the normal subjects. 0.84 ± 0.11, 0.82 ± 0.1, and 0.81 ± 0.07, p < 0.01, respectively. Three of the four non-diabetic patients with neuropathic foot ulceration also had an abnormally low TBI. Reduced toe pressure measurements are thus found to be associated with neuropathic foot ulceration. The contribution of distal ischaemia in the pathogenesis of the diabetic neuropathic foot ulcer needs to be evaluated. One hundred and eight non-insulin-dependent diabetic patients who had been tested for autonomic dysfunction in 1984/85 were re-evaluated 5 years later. Autonomic function was assessed by means of four cardiovascular tests (heart rate variation during deep breathing and standing, and blood pressure variation after standing and sustained handgrip). Eighteen subjects were lost to follow-up; in the 90 patients who completed the study, both the deep breathing and the handgrip test significantly worsened (respectively from 13.7 ± 7.8 to 11.6 ± 6.3 beats min^?1 p < 0.01, and from 16.9 ± 8.2 to 12.7 ± 7.1 mmHg, p < 0.001), whereas both the 30:15 ratio and the variation of blood pressure on standing did not change. The impairment of a comprehensive evaluation score (from 2.5 ± 1.7 to 3.0 ± 1.5; p < 0.05) also confirmed the gradual deterioration of autonomic function over the study period.