The anterior scalene muscle in thoracic outlet compression syndrome. Histochemical and morphometric studies

Histochemical studies and morphometric fiber type analysis were done on biopsy specimens of anterior scalene muscle (ASM) from patients with thoracic outlet compression syndrome (TOS), without structural abnormality. Hypertrophy and atrophy factors were determined from muscle fiber histograms of ASM from controls, patients with TOS, and after scalene tenotomy. Scalene muscle from patients with TOS showed marked type 1 (tonic contracting) fiber predominance (85.1% +/- 5.1%) and type 1 fiber hypertrophy (55.6 +/- 2.7 microns). After tenotomy there is a reduction of type 1 fiber representation, selective atrophy in the type 1 fiber system (atrophy factor, 0.66 +/- 0.24), and increase of type 2 fibers. These distinctive changes indicate that ASM is uniquely structured in fiber composition to sustain prolonged contraction. The ASM in patients with TOS demonstrates an extraordinary adaptive transformation and recruitment response in the type 1 fiber system reflecting chronic increased tone or motor neuron stimulation. These observations form a basis for clarifying the structural and pathophysiologic changes in TOS.     

Selective Botulinum Chemodenervation of the Scalene Muscles for Treatment of Neurogenic Thoracic Outlet Syndrome

Patients with thoracic outlet syndrome (TOS) who improve temporarily after anesthetic blockade of the anterior scalene muscles have been shown to improve after ultimate surgical decompressions at the interscalene triangle. Anesthetic blockade of the scalene muscles, even with the addition of steroids, however, rarely produces any prolonged relief as patients are awaiting definitive surgery. The present study was undertaken to determine if more effective and prolonged relief might be obtained with electrophysiologically and fluoroscopically guided selective injection of the scalene muscles with botulinum toxin, which has been used in the past for treating conditions associated with spasm of cervical muscles. In 14 of 22 patients (64%) with a clinical diagnosis of TOS, there was more than a 50% reduction of symptoms measured by a 101-point scale for at least 1 month after botulinum chemodenervation of the scalene muscles. Only 4 of the 22 patients (18%) had a 50% reduction of symptoms for at least 1 month after injection with lidocaine and steroids. In no patient were the results of lidocaine and steroid injection superior to botulinum chemodenervation. Chemodenervation had a mean duration of effect of 88 days. No significant side effects were encountered with botulinum chemodenervation except for mild transient dysphagia in two cases. These results appear to demonstrate that botulinum chemodenervation of the scalene muscles may be helpful in alleviating symptoms in patients with TOS awaiting definitive surgical decompression.     

在内窥镜辅助下手术治疗胸廓出口综合征10例报告

目的 报告并探讨一个治疗胸廓出口综合征(thoracic outlet syndrome，TOS)的新方法，即在内窥镜辅助下进行手术治疗。方法 局部麻醉下在颈外侧作1．5cm长的小切口，在内窥镜的辅助观察下，切断部分前中斜角肌的腱性起始纤维。结果 2092年3月11日至2002年12月16日，共作10例。手术当天10例的症状和体征均完全消失。术后随访4个月～1年，平均6个月。5例的症状和体征完全消失。4例的肌力恢复正常，前臂和小指的刺痛觉稍减退。1例仅偶有颈部不适的症状，术侧锁骨区有麻痛，针刺有痛觉过敏。结论 在内窥镜辅助下经颈部微小切口切断部分前中斜角肌的腱性起始纤维，可解除斜角肌对臂丛神经的压迫，是一个创伤很小的治疗胸廓出口综合征的新方法。     

Surgical management of thoracic outlet syndrome: a 10-year experience

BACKGROUND: Thoracic Outlet Syndrome (TOS) refers to compression of the neurovascular structures in the region between the scalene muscles and the first rib, or by anatomical abnormalities such as cervical rib, fibrous bands and other variations in the scalene musculature. METHODS: Our experience with 63 consecutive operations for TOS, over a period of 10 years, has been reviewed. Preoperative symptoms and signs, investigations, surgery done, complications and the outcome of surgery are analysed. RESULTS: A total of 60 patients underwent 63 operations for decompression of TOS. All the 63 first ribs, were excised by the transaxillary approach. In seven patients (16%), a combined transaxillary and supraclavicular approach was used. There was no operative mortality in this series. The operative complications included pneumothorax in four patients (6.3%), which was treated by insertion of chest drain, and lower brachial plexus neuropraxia in two patients (3%), which improved with conservative management. The mean duration of postoperative hospital stay was 3.6 days. At 12 months following surgery, 56 patients (93%) had complete or partial relief of symptoms and only four patients (6.6%) had no relief of symptoms. CONCLUSION: The results of the present study confirm that transaxillary excision of the first rib is a surgical procedure associated with very low morbidity and excellent relief of symptoms. It can therefore be offered as an early option for patients with thoracic outlet syndrome. It may be combined with the supraclavicular approach if exposure of the subclavian artery is required for vascular reconstruction.     

Upper plexus thoracic outlet syndrome--case report

A 47-year-old right-handed female became aware of proximal ache and muscle weakness in the right shoulder and elbow in 1997. Atrophy of the right biceps muscle was recognized and the right deltoid, triceps, supraspinatus, and infraspinatus muscles were weak. The Morley test and elevated arm stress test were positive. Neurolysis of the brachial plexus and anterior scalenectomy were performed via a right supraclavicular approach. An abnormal fibromuscular band was identified passing between the upper and middle trunks and constricting the middle trunk. Another scalene muscle anomaly was found passing between the C-5 and C-6 nerve roots and connecting the anterior and middle scalene muscles. These muscles were resected, and thorough neurolysis was performed around all nerves and the trunks. Postoperatively, all symptoms completely resolved and the patient was discharged 5 days after surgery. Thoracic outlet syndrome (TOS) manifests as symptoms of lower cervical nerve involvements with hypesthesia and paresthesia. However, upper plexus TOS manifests as symptoms due to the involvement of the C-5 to C-7 nerve roots, and is relatively rare. Transaxillary first rib resection is performed as the primary operation for TOS, but supraclavicular scalenectomy is effective for upper plexus TOS.     

切断前中小斜角肌治疗胸廓出口综合征的远期疗效

目的 远期随访切断前中斜角肌治疗胸廓出口综合征（thoracic outlet syndrome，TOS）的疗效。方法对31例32侧胸廓出口综合征患者术后的疗效作远期随访。其中上干型4例，下干型26例27侧，全臂丛型1例。X线片示颈肋1例。第七颈椎横突过长2例。均行手术治疗。术中发现31例均有纤维束带压迫臂丛神经，作前、中、小前斜角肌切断术；3例骨异常者同时切除增长的骨组织和颈肋。术后随访4年8个月-8年3个月．平均为5年4个月。以症状、体征有无复发以及是否恢复原工作为随访主要观察项目。疗效按胸廓出口综合征评定标准评定。结果 术后症状明显改善15例16侧，部分改善6例，无效10例。优良率为68．7％。结论 该组病例远期疗效的优良率为68．7％，因此，胸廓出口综合征的治疗方法仍是个有待于进一步研究的临床课题。     

Diagnosis of patients with thoracic outlet syndrome (TOS) using physiological measures of the medial antebrachial cutaneous nerve

The diagnosis of thoracic outlet syndrome (TOS) remains difficult; therefore, reliable and objective tests are required. We examined the process to diagnose TOS, and assessed the validity of measuring the medial antebrachial cutaneous nerve (MAC), also the ulnar nerve (UN) as a diagnostic tool. Between 2008 and 2011, 86 sides in 73 patients admitted to our hospital for the treatment of TOS were analyzed. In the process for the diagnosis as TOS, the narrow parts of the subclavian artery that was compressed by the anterior scalene muscle were confirmed with a three-dimensional CT angiography. All patients were taken a brachial plexus anesthesiological block to aim at both for diagnosis and treatment of TOS. For the diagnosis of TOS, measurements of latency (LT) and sensory nerve action potential (SNAP) of MAC and UN were analyzed between the TOS side and the non-TOS side and separated into traumatic type or disputed type. In our research, the LT of MAC and UN did not differ much between the TOS side and the non-TOS side; however, the amplitude of SNAP of MAC and UN were lower on the TOS side, especially in traumatic TOS. We concluded that comparison of the amplitude of SNAP of MAC on the injured or non-injured side was comparatively helpful for the diagnosis of TOS.     

臂丛神经卡压综合征的诊治

目的探讨位于臂丛神经及其前中斜角肌周围的神经卡压综合征的特点及其诊治方法。方法2003年7月～2006年1月,采用门诊收集病例,根据病情轻重分组,分别采用药物、局部封闭及手术方法治疗179例确诊为臂丛神经和(或)其属支卡压综合征的患者。其中采用药物、手法治疗89例；注射治疗74例,其中需要第二次注射32例；手术治疗16例,同时或分别进行双侧手术2例,需要第二次手术者1例。结果128例患者得到1个月～2年5个月随访。其中,药物手法治疗55例,症状均有不同程度改善或能维持现状。局部注射治疗58例(其中接受第二次注射者24例),2例出现心跳减缓,其余病例无并发症发生,VAS评分情况：1分2例,2分16例,3分20例,4分12例,5分3例,6分3例,7分2例；第二次注射结果：2分5例,3分16例,4分3例。手术治疗15例,其中10例术后症状得到明显改善,恢复工作。结论臂丛神经及其属支涉及其周围众多神经,可产生众多症状；明确病因后,治疗上以保守治疗为主,效果欠佳者采用手术治疗,均可取得较好疗效。     

胸廓出口综合征的新认识——解剖学与临床观察

目的探讨胸廓出口综合征的病因。方法对３０具６０侧经福尔马林固定的成人尸体小斜角肌及前中斜角肌的起始部进行解剖研究;对５３例胸廓出口综合征手术患者（１９６６～１９９４年４５例,１９９６～１９９７年８例）随访情况进行总结分析。结果解剖研究发现小斜角肌的出现率为８８３％,Ｔ１神经根或其下干在小斜角肌近段起源的腱性组织上跨过;前中斜角肌在颈椎横突的前后结节均有起点,Ｃ５、Ｃ６神经根从前中斜角肌的交叉腱性起点中穿过。４５例１９６６～１９９６年手术者中,有颈肩痛症状者３４例,术后１７例颈肩痛症状仍存在,其中７例加重;８例１９９６～１９９７年手术者中,７例有颈肩痛,术中切断前中斜角肌在Ｃ５～６神经根旁的腱性纤维组织,术后仅有１例仍有颈肩部不适。结论小斜角肌的腱性纤维是臂丛神经下干或Ｔ１神经根受压的原因;前中斜角肌在Ｃ４～５横突前后结节的交叉腱性起点是压迫Ｃ５～６,有时包括Ｃ７神经根或臂丛神经上（中）干的原因     

Developmental anomalies at the thoracic outlet: an analysis of 200 consecutive cases.

Anatomic observations were made during 200 consecutive transaxillary surgical procedures performed in 175 patients because of unremitting signs and symptoms of nerve or vascular compression at the thoracic outlet. There were 160 cases of brachial plexus compression and 40 cases of arterial or venous occlusion. In 132 (66%) of these cases, single or multiple abnormalities were recognized that represented developmental variations previously described in anatomic dissections or in embryologic studies. There were 17 cases of cervical rib or first thoracic rib abnormalities and 20 supernumerary scalene muscles. Developmental variations were identified in 86 scalene and 39 subclavius muscles or their insertions. Comparisons revealed a higher percentage of developmental anomalies in this group of patients than in consecutive anatomic investigations reported in unselected populations. This information was interpreted in light of recent embryologic studies and histochemical and morphometric ultrastructural studies of scalene muscle. The preponderance of evidence suggests that neurovascular compression in the region of the thoracic outlet derives from a combination of these factors: predisposing morphologic variations, structural modifications conditioned by functional requirements, and changes in fiber type or myosin isoform consequent to trauma. The correlation of clinical syndrome with morphologic characteristics alone was significant only for the Paget-Schroetter syndrome.     

Diagnosis of thoracic outlet syndrome

Thoracic outlet syndrome (TOS) is a nonspecific label. When employing it, one should define the type of TOS as arterial TOS, venous TOS, or neurogenic TOS. Each type has different symptoms and physical findings by which the three types can easily be identified. Neurogenic TOS (NTOS) is by far the most common, comprising well over 90% of all TOS patients. Arterial TOS is the least common accounting for no more than 1%. Many patients are erroneously diagnosed as "vascular" TOS, a nonspecific misnomer, whereas they really have NTOS. The Adson Test of noting a radial pulse deficit in provocative positions has been shown to be of no clinical value and should not be relied upon to make the diagnosis of any of the three types. The test is normal in most patients with NTOS and at the same time can be positive in many control volunteers. Arterial TOS is caused by emboli arising from subclavian artery stenosis or aneurysms. Symptoms are those of arterial ischemia and x-rays almost always disclose a cervical rib or anomalous first rib. Venous TOS presents with arm swelling, cyanosis, and pain due to subclavian vein obstruction, with or without thrombosis. Neurogenic TOS is due to brachial plexus compression usually from scarred scalene muscles secondary to neck trauma, whiplash injuries being the most common. Symptoms include extremity paresthesia, pain, and weakness as well as neck pain and occipital headache. Physical exam is most important and includes several provocative maneuvers including neck rotation and head tilting, which elicit symptoms in the contralateral extremity; the upper limb tension test, which is comparable to straight leg raising; and abducting the arms to 90 degrees in external rotation, which usually brings on symptoms within 60 seconds.     

Dynamic neuromusculoskeletal ultrasound documentation of brachial plexus/thoracic outlet compression during elevated arm stress testing

Background

The diagnosis and validation of thoracic outlet syndrome/brachial plexopathy (TOS) remains a difficult challenge for surgeons, neurologists, and radiologists. This is due to the fact that the responses of standard elevated arm stress tests can be considered somewhat subjective and can vary. Therefore, non-vascular TOS cases are presently diagnosed clinically, and any objective diagnosis has been controversial.

Methods

This is a technique paper describing the use of dynamic neuromusculoskeletal ultrasound to assist in the diagnosis of thoracic outlet/brachial plexus pathology. We propose a new way to observe the brachial plexus dynamically, so that physical verification of nerve compression between the anterior and middle scalene muscles can be clearly made at the onset of clinical symptoms. This gives a way to objectively identify clinically significant brachial plexus compression.

Results

Dynamic testing can add objective analysis to tests such as the elevated arm stress tests and can correlate the onset of symptoms with plexus compression between the anterior and middle scalene muscles. With this, the area of pathologic compression can be identified and viewed while performing the dynamic testing. If compression is seen and the onset of symptoms ensues, this is a positive confirmatory test for the presence of TOS and a clinically significant disease.

Conclusions

This paper offers a simple, objective, and visual diagnostic test that can validate the presence or absence of brachial plexus compression during arm elevation in patients with brachial plexus injury and thoracic outlet syndrome.     

表情肌肌纤维组织化学分裂及分类研究

目的 对活体表情肌组织化学特点进行研究,为面部表情肌动脉复活提供实验依据。方法 标本均取自头面颈部手术病人切口下和的表情肌,并在拟冷切片机中切片后进行组织化学染色,包括肌动球蛋白ＡＴＰ酶（ＭＡＴＰａｓｅ）及 的型畏酶１－四唑氮蓝（ＮＡＤＡ－ＴＲ）,结果依靠计算机辅助图像分析。结果 各表情肌肌纤维直径在２４．３～６３．９μｍ之间不等,表情肌中同一型肌纤维直径不相同,Ｐ〈０．０５,各表情肌中各型肌数量     

Spinal muscle evaluation in healthy individuals and low-back-pain patients: a literature review

This article reviews available techniques for spinal muscle investigation, as well as data on spinal muscles in healthy individuals and in patients with low back pain. In patients with chronic low back pain, medical imaging studies show paraspinal muscle wasting with reductions in cross-sectional surface area and fiber density. In healthy individuals, the paraspinal muscles contain a high proportion of slow-twitch fibers (Type I), reflecting their role in maintaining posture. The proportion of Type I fibers is higher in females, leading to better adaptation to aerobic exertion compared to males. Abnormalities seen in paraspinal muscles from patients with chronic low back pain include marked Type II fiber atrophy, conversion of Type I to Type II fibers, and an increased number of nonspecific abnormalities. Limited data are available from magnetic resonance spectroscopy used to investigate muscle metabolism and from near infrared spectroscopy used to measure oxygen uptake by the paraspinal muscles. Surface electromyography in patients with chronic low back pain shows increased paraspinal muscle fatigability, often with abolition of the flexion-relaxation phenomenon.     

胸廓出口综合征手术方法改良

目的 在解剖学研究和临床分析的基础上提出了胸廓出口综合征手术方法的改良。方法 ３０例尸体解剖,研究前、中、小斜角肌的起止点和臂丛神经的关系。随访了术后６个月￣２年的１９例颈肩痛和手部麻木,肌肉萎缩的胸廓出口综合征患者,均做前,中斜角肌起点和小斜角肌切断术。     

Histochemical and contractile properties of striated muscles of urethra and levator ani of dogs and sheep

AIMS: To understand their possible importance in long- and short-term control of continence, some properties of the striated muscles of the urethra and pelvic floor (levator ani) of dogs and sheep were investigated, especially fiber types and contractile characteristics. MATERIALS AND METHODS: Striated muscles of urethra and levator ani of 29 male and 6 female dogs and 11 male and 6 female sheep were removed and cut into strips. Some strips were frozen and stained for ATPase at pH 9.4 and 4.3 for fiber typing; others were set up in an organ bath to study contractile responses to nerve stimulation. RESULTS: All muscles contained both type I (slow) and type II fibers, ranging from 97% type II in female greyhound urethra to 60% in female sheep levator ani. For each muscle, there were fewer type II muscles in sheep than in dog. The diameters of the urethral fibers were about 60% of the levator ani in dogs and 34% in sheep. Contraction of the urethral muscle was faster than for levator ani and declined to about 80% of the peak, 500 msec after the beginning of stimulation at 20 Hz. The levator ani contraction rose to a steady level as long as stimulation continued. CONCLUSIONS: Both the levator ani and urethral striated muscles contain slow and fast fiber types. The levator ani muscles are capable of sustained contraction with rapid onset which will produce long-term closure of the urethra. The circular urethral muscle contraction was faster but less well maintained.     

Fiber-type specific caffeine sensitivities in normal human skinned muscle fibers

Caffeine sensitivity was studied in chemically skinned muscle fibers from vastus lateralis muscle obtained by biopsy during reconstructive knee surgery from 15 otherwise healthy young individuals. Muscle fiber type was determined by contracture occurring in strontium (slow-oxidative, type I fiber) or calcium (both type I and type II, fast glycolytic fiber) solutions and in several fibers after contracture testing by ATPase enzyme histochemistry. Caffeine sensitivity (mean +/- SD), defined as the threshold concentration inducing more than 10% of the maximal tension obtained with a calcium 3 x 10(-5) mM solution was 2.7 +/- 1.3 mM in 37 type I fibers, whereas it was 6.9 +/- 2.4 mM in 61 type II fibers. A paired t test showed a significantly increased sensitivity to caffeine in type I fibers (P less than 0.001) in 13 individuals in whom the two fiber types were identified. The mean (+/- SD) difference between type I and type II fibers was 4.1 +/- 1.9 mM. Type I fibers contracted with greater tension in response to the increasing concentration of caffeine than did type II fibers (P less than 0.05). These skinned fiber studies showed significantly different caffeine sensitivities between human type I and type II muscle fibers, as previously shown in animal muscles. The findings that human type I muscle fibers have higher caffeine sensitivity than type II muscle fibers should be helpful for the interpretation of the in vitro contracture test done in muscle strips containing type I and type II fibers in varying proportions.     

Etiology and pathology

Until the 1920s, TOS was believed to be a vascular condition caused by compression of the subclavian artery by a congenital anomaly, either a cervical rib or tight anterior scalen muscle. Today it is regarded primarily as a neurologic condition caused by neck trauma injuring and scarring the scalene muscles.     

Pediatric thoracic outlet syndrome: a disorder with serious vascular complications

Background

Thoracic outlet syndrome (TOS), caused by compression of the neurovascular structures between the clavicle and scalene muscles, typically presents with neurologic symptoms in adults. We reviewed our experience with 25 adolescents and propose a diagnostic/treatment algorithm for pediatric TOS.

Methods

From 1993 to 2005, 25 patients were treated with TOS. A retrospective chart review was performed with institutional review board approval. Demographics, clinical presentation, diagnostic studies, and treatment were evaluated.

Results

Seven male (28%) and 18 female (72%) patients presented between the ages of 12 to 18 years. Thirteen (52%) had vascular TOS (11 venous, 2 arterial), 11 (44%) had neurologic TOS, and 1 had both. Vascular TOS included subclavian vein thrombosis (7), venous impingement (4), and arterial impingement (2). Three patients had hypercoagulable disorders, and 6 had effort thrombosis. Venography was diagnostic in 10 cases. Neurogenic TOS was diagnosed by clinical symptoms. Five patients with subclavian vein thrombosis underwent thrombolysis, with 3 maintaining long-term patency. Of 25 patients, 24 underwent transaxillary first rib resection.

Conclusion

Vascular complications are more common in adolescents with TOS than in adults. A diagnostic/treatment algorithm includes urgent venography and thrombolysis for venous TOS and a workup for hypercoagulability. Neurogenic TOS is diagnosed clinically, whereas other studies are rarely beneficial.     

Morphology of the paravertebral muscles in adolescent idiopathic scoliosis

Histochemical studies of paravertebral muscles in idiopathic scoliosis have shown a consistently higher proportion of type I fibers on the convex side. In this study of the transversospinal muscles in moderate idiopathic scoliosis, we could demonstrate a lower type II B/II A fiber ratio on the convex side, along with an increased proportion of type I fibers. The capillary count was also higher on the convex side, especially around the type I fibers. The few pathologic changes found were predominately seen in the gravest cases of scoliosis. It is concluded that the fiber type distribution, capillary count, and metabolic enzyme activity on the convex side resembles that seen after endurance training. This suggests a secondary adaptive origin of these changes.