磁共振成像在诊断成人臂丛神经牵拉伤中的作用

1996～1997年间,连续对26例臂丛神经牵拉伤的患者行颈椎和臂丛神经的磁共振成像(MPI)检查,获得颈椎冠状面、矢状面、轴位及臂丛冠状面的T1和T2加权像,并将其与外科所见、术中神经电生理学表现及随后的临床进展过程进行了比较。对23例患者实施了探查及神经修复术。26例均进行了MRI扫描,其中11例表现明显的根性撕脱,具体表现为脊髓移位或水肿、椎管内出血或瘢痕形成、椎间孔内神经根消失和脑脊膜突出。所有经神经探查证实存在神经根撕脱伤的病例,磁共振扫描均显示明显的特异性异常改变,且无假阳性。但是磁共振成像诊断神经根撕脱也有一定的漏诊率,其灵敏度为81％。节后损伤在T1像显示为膨胀影且在T2像表现为加强,这样就大致可以确定神经丛损伤的水平。这项研究提示臂丛牵拉伤后早期行磁共振成像检查,对于确定损伤水平可提供有用的信息,而且对于椎管外神经丛的损伤,磁共振成像也可提供有用的信息。     

Imaging of adult brachial plexus traction injuries

Closed, high-energy transfer traction injuries of the adult brachial plexus lead to rupture or avulsion of the spinal nerves. Accurate preoperative diagnosis is crucial for surgical planning and reconstruction. Myelography, computerised tomographic myelography and magnetic resonance imaging are the main radiological methods for preoperative diagnosis of the lesion. This article reviews the current status of imaging of traction injuries of the adult brachial plexus.     

Supraclavicular traction injuries of the brachial plexus.

Thirty supraclavicular traction injuries of the brachial plexus are reported. Young motor cyclists are frequently involved. Recovery is slow and often incomplete. Myelography remains the most useful investigation for prognostic purposes. The management of intractable pain is discussed. An early assessment of prognosis is an important fact in planning and supervising the long-term management of these patients.     

Nerve transfer in brachial plexus traction injuries.

Brachial plexus palsy due to traction injury, especially spinal nerve-root avulsion, represents a severe handicap for the patient. Despite recent progress in diagnosis and microsurgical repair, the prognosis in such cases remains unfavorable. Nerve transfer is the only possibility for repair in cases of spinal nerve-root avulsion. This technique was analyzed in 37 patients with 64 reinnervation procedures of the musculocutaneous and/or axillary nerve using upper intercostal, spinal accessory, and regional nerves as donors. The most favorable results, with an 83.8% overall rate of useful functional recovery, were obtained in patients with upper brachial plexus palsy in which regional donor nerves, such as the medial pectoral, thoracodorsal, long thoracic, and subscapular nerves, had been used. The overall rates of recovery for the spinal accessory and upper intercostal nerves were 64.3% and 55.5%, respectively, which are significantly lower. The authors evaluate the results of nerve transfer and analyze different donor nerves as factors influencing the prognosis of surgical repair.     

Restoration of upper arm function in traction injuries to the brachial plexus

Summary. Summary.   Background: Restoration of upper arm function presents the main priority in nerve repair of brachial plexus traction injuries. The results are predominantly influenced by the level and extent of injury, and the type of surgical procedure. The purpose of this study is to evaluate influence of these factors on final outcome.   Methods: Study included 91 surgically treated patients, including 71 patients with avulsions of one or more spinal nerve roots and 20 with peripheral traction injuries. We performed 120 nerve transfers, 25 nerve graftings and 29 neurolyses on different nerve elements depending on the type of nerve damage. Analysis of motor recovery for elbow flexion and arm abduction, isolated or in combination, was done.   Findings: Recovery of elbow flexion was obtained in 75% nerve transfers, and in 68,7% nerve graftings in peripheral traction injuries. Recovery of arm abduction was obtained in 78,5% nerve transfers, and in 44,4% nerve graftings in peripheral traction injuries. Neurolysis was successful in all cases. Generally, the quality of recovery was better for the musculocutaneous nerve. Useful global upper arm function was obtained in 49,3% of patients with avulsion of spinal nerve roots, and in 55% of patients with peripheral traction injuries.   Interpretation: Regarding upper arm function the prognosis of surgically treated patients with traction injuries to the brachial plexus is generally similar in cases with central or peripheral level of injury. However, nerve transfers of collateral branches seem to be superior to nerve grafting and may be another possibility for repair in cases with extensive nerve gaps.     

Computerised axial tomography in traction injuries of the brachial plexus

Severe traction injuries may damage the brachial plexus at any level from the spinal cord to the axillary outlet. Investigation aims to determine the level of the injury for each of the nerves, trunks or cords, with particular reference to obtaining firm evidence of any intradural (pre-ganglionic) damage. We report the results of computerised axial tomography of the cervical spine in comparison with conventional myelography and with surgical exploration of the plexus. CT scanning with contrast enhancement greatly improves diagnostic accuracy, particularly at C5 and C6 root levels.     

A magnetic resonance imaging study of modifications to the infraclavicular brachial plexus block

A previously described infraclavicular brachial plexus block may be modified by using a more lateral needle insertion point, while the patient abducts the arm 45 degrees or 90 degrees. In performing the modified block on patients abducting 45 degrees, we often had problems finding the cords of the brachial plexus. Therefore, we designed an anatomic study to describe the ability of the recommended needle direction to consistently reach the cords. Additionally, we assessed the risk of penetrating the pleura by the needle. Magnetic resonance images were obtained in 10 volunteers. From these images, a virtual reality model of each volunteer was created, allowing precise positioning of a simulated needle according to the modified block, without exposing the volunteers to actual needle placement. In both arm positions, the recommended needle angle of 45 degrees to the skin was too shallow to reach a defined target on the cords. Comparing the two arm positions, target precision and risk of contacting the pleura were more favorable with the greater arm abduction. We conclude that when the arm is abducted to 90 degrees, a 65 degrees -needle angle to the skin appears optimal for contacting the cords, still with a minimal risk of penetrating the pleura. However, this needs to be confirmed by a clinical study.     

Defining the cross-sectional anatomy important to interscalene brachial plexus block with magnetic resonance imaging

Background and Objectives. Interscalene brachial plexus block is a useful technique to provide anesthesia and analgesia for the shoulder and proximal upper extremity. The initial needle direction at the interscalene groove has been described as being “perpendicular to the skin in every plane” (1). A cross-sectional (axial) approach may offer a more easily conceptualized directed needle placement. The purpose of this study is to define the cross-sectional anatomy and idealized needle angles important to interscalene brachial plexus block. Methods. Following IRB approval, 50 patients were studied. Cross-sectional volume coil T1-weighted magnetic resonance images (MRI) were obtained from 50 patients undergoing cervical region imaging for other reasons. At the interscalene groove, a simulated needle path to contact the ventral rami or trunks of the brachial plexus was approximated at the level of C6 or C6–C7 interspace. The angle of this needle path intersecting the sagittal plane was recorded for each patient. Results. The mean angle of the simulated needle path relative to sagittal plane was determined to be 61.1 ± 6.1° (range, 50–78°). In 13 of 50 (26%) MRI scans, the cervical nerve roots were not visualized at the level of C6 and were measured at the C6–C7 level. Conclusions. These findings suggest initial needle placement at the interscalene groove should be angled less perpendicularly relative to the sagittal plane than is often observed. A cross-sectional approach enables more practical visualization of initial needle placement. A more accurate initial needle placement may minimize the number of needle passes necessary to contact the nerve roots, thereby more efficiently obtaining a successful block.     

Magnetic resonance imaging in brachial plexus injury

Brachial plexus injury represents the most severe nerve injury of the extremities. While obstetric brachial plexus injury has showed a reduction in the number of cases due to the improvements in obstetric care, brachial plexus injury in the adult is an increasingly common clinical problem. The therapeutic measures depend on the pathologic condition and the location of the injury: Preganglionic avulsions are usually not amenable to surgical repair; function of some denervated muscles can be restored with nerve transfers from intercostals or accessory nerves and contralateral C7 transfer. Postganglionic avulsions are repaired with excision of the damaged segment and nerve autograft between nerve ends or followed up conservatively. Magnetic resonance imaging is the modality of choice for depicting the anatomy and pathology of the brachial plexus: It demonstrates the location of the nerve damage (crucial for optimal treatment planning), depicts the nerve continuity (with or without neuroma formation), or may show a completely disrupted/avulsed nerve, thereby aiding in nerve-injury grading for preoperative planning. Computed tomography myelography has the advantage of a higher spatial resolution in demonstration of nerve roots compared with MR myelography; however, it is invasive and shows some difficulties in the depiction of some pseudomeningoceles with little or no communication with the dural sac.     

Strategies in the microsurgical management of brachial plexus injuries

The authors' experience in the management of brachial plexus injuries over three periods of evolution is presented. Developments in microsurgery have expanded the strategies in brachial plexus management, and these are discussed in full.     

Surgical management of brachial plexus injuries.

Exploration of the brachial plexus was done as an elective procedure in 56 patients with complete or partial lesions. The indications were based on clinical findings, a Tinel-Hoffman sign indicating that at least one root was available for direct repair, or a cessation of signs of progressive recovery. In young patients with supraganglionic lesions and evidence of root avulsion, nerve grafts from intercostals to various portions of the plexus were done. Evaluation of the results of motor functions showed that 38 of 54 (70 percent) recovered a useful motor function in at least one important area. There were two postoperative hematomas leading to delayed healing and failure of nerve recovery. Two patients had temporary loss of power in uninvolved muscles but both recovered satisfactory function. Only one patient had a persistent pain syndrome. Two failures were due to the late operation (19 months after injury) and one because of a 15 cm. which was grafted.     

Recent advances in the management of brachial plexus injuries

Management of brachial plexus injury is a demanding field of hand and upper extremity surgery. With currently available microsurgical techniques, functional gains are rewarding in upper plexus injuries. However, treatment options in the management of flail and anaesthetic limb are still evolving. Last three decades have witnessed significant developments in the management of these injuries, which include a better understanding of the anatomy, advances in the diagnostic modalities, incorporation of intra-operative nerve stimulation techniques, more liberal use of nerve grafts in bridging nerve gaps, and the addition of new nerve transfers, which selectively neurotise the target muscles close to the motor end plates. Newer research works on the use of nerve allografts and immune modulators (FK 506) are under evaluation in further improving the results in nerve reconstruction. Direct reimplantation of avulsed spinal nerve roots into the spinal cord is another area of research in brachial plexus reconstruction.KEY WORDS: Brachial plexus injuries, nerve grafts, recent advances, reimplantation of avulsed spinal nerve roots, selective nerve transfers     

Treatment of adult and obstetrical brachial plexus injuries

Twenty-five percent of patients with injuries to the plexus require surgical intervention for optimal results. Patients with loss of serratus and rhomboids, Horner's syndrome, positive myelogram, or negative evoked potentials have a high incidence of lower root avulsions and a probability of upper root ruptures. These should be explored early. Results depend on the amount of remaining axonal input available for grafting. Using intraoperative electrical studies, elements which will recover spontaneously may be saved and improved function obtained by grafting only damaged elements. Obstetrical palsy patients should be immobilized for several weeks; passive stretching should then be done. Recovery within 2 months yields a normal arm; if recovery of the biceps or arm occurs within 3 months, the arm will be good. If biceps recovery has not begun by the third month, surgical intervention with appropriate repair will yield at least one grade higher function than in conservatively treated patients.     

The vertical infraclavicular brachial plexus block: a simulation study using magnetic resonance imaging

The recommended needle trajectory for the vertical infraclavicular brachial plexus block is anteroposterior, caudad to the middle of the clavicle. We studied the risk of pneumothorax and subclavian vessel puncture and the precision of this method by using magnetic resonance imaging in 20 adult volunteers. The trajectory aimed at the lung in six subjects, five of whom were women. However, pleural contact could be avoided in all subjects by halting needle advancement after contact with the subclavian vessels, plexus, or first rib. The subclavian vein was reached by the trajectory in three and the subclavian artery in five subjects. The trajectory had a median distance to the plexus (closest aspect) of 1 mm (range, 0-9 mm) and contacted the nerves in 9 subjects. In conclusion, there is a small probability that the needle may reach the pleura when a vertical infraclavicular brachial plexus block is performed, particularly in women, and a high probability that it will contact the subclavian vein or artery. Although the trajectory is close to the plexus, any medial deviation carries the risk of pleural or subclavian vessel contact at other depths. Clinical accuracy in defining the insertion point is critical.     

The treatment of brachial plexus injuries

Summary The author describes 1068 patients with brachial plexus lesions who were referred to him during a period of 18 years. Seventy two percent of the injuries were caused by road traffic accidents. Traction or crush injuries were the usual type encountered. They may occur at five levels above, behind and below the clavicle.Of 329 patients who underwent operation, 23% had an associated injury of a major vessel and 80% had multiple injuries elsewhere. The operative approach preferred is described and the principles governing the choice of nerve repair, nerve graft and nerve transfer are discussed. The details of the problems encountered and the procedures carried out in this group of patients are given, and the results obtained are closely analysed. In about 15% of supraclavicular injuries reconstruction of the plexus is worthwhile. The results in infraclavicular lesions are much better with a high level of success if treated early.Only 5 patients had direct lacerations of nerves of the plexus and another 5 had suffered gunshot wounds.Only 11 out of 80 cases of obstetric palsy seen since 1976 have been operated on. The majority of the patients were seen late. At operation similar lesions were encountered as in adults, and useful improvement was obtained in some cases.In post-irradiation lesions of the plexus good results may be obtained if operation is undertaken early. Otherwise surgery should only be performed to relieve severe pain.

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Résumé L'auteur décrit 1068 patients présentant une lésion du plexus brachial, qui lui ont été adressés en 18 ans. 72% des lésions étaient causées par les accidents de la circulation routière. Il s'agissait habituellement de lésions par élongation ou écrasement qui se produisent à cinq niveaux différents, au-dessus, en arrière et en dessous de la clavicule.23% des 329 cas opérés présentaient une lésion vasculaire majeure associée et dans 80% des cas, il s'agissait de polytraumatisés. L'auteur décrit son approache chirurgicale et son choix de réparation nerveuse par greffes ou transferts nerveux, en détaillant les problèmes que l'on rencontre, les procédés utilisés dans ce groupe de patients et il analyse les résultats obtenus.A peu près dans 15% des cas avec lésions susclaviculaires, il vaut la peine de procéder à une reconstruction plexuelle. Les résultats des réparations infra-claviculaires sont nettement meilleurs, avec un taux de succès élevé si la réparation est faite précocément.5 patients seulement ont présenté des sections du plexus et 5 opérés avaient des lésions par projectiles.Sur 80 cas de paralysie obstétricale vus dès 1976, 11 seulement ont eu une réparation chirurgicale directe du plexus. La majorité d'entre eux furent vus tard après le traumatisme obstétrical. Des lésions similaires à celles de l'adulte furent observées opératoirement et une amélioration utile fut obtenue dans quelques cas. Dans les plexopathies par radiothérapie, de bons résultats sont obtenus si l'opération est précoce; sinon, la chirurgie n'est indiquée que pour amender les états douloureux.