Intraoperativ evozierte Potentiale bei traumatischen Armplexusläsionen

Abstract

The operative treatment of brachial plexus injuries still remains a challenge. A thoroughful evaluation of the kind and extension of a lesion is required in each individual case to come to the appropriate therapeutical decision. In this regard the knowledge of the level in a given lesion (pre- or postganglionic) is of special importance. Especially in traction injuries, however, the lesion site can be more widespread, including both the pre- and postganglionic division of plexus elements (fig. 1). Up till now there is no way of direct repair of nerve roots avulsed from the spinal cord. In cases of root avulsion muscle and/or tendon transfers (9) or neurotisation procedures (8) are indicated. In addition to the clinical evaluation EMG, SEP, NAP and sweat tests can be valuable tools to differenciate preoperatively between a pre- and a postganglionic lesion. Myelography and intrathecal contrast CT have proven to be useful in detecting cervical root avulsion (10, 12, 15). In some cases, however, the level of the injury remains unclear before surgery (7). For the surgeon, planning direct nerve repair, it is important to know if the most proximal part of the plexus i. e. the nerve roots is intact (anatomically and moreover functionally) before he uses the central stump of a nerve root in a grafting procedure. In 16 patients with traumatical brachial plexus injuries (aged between 16 and 32 years), who underwent surgery for direct nerve repair we stimulated intraoperatively 42 cervical nerve roots (C4-Th1) close to the foramen intervertebrale with electrical stimuli (0-10 mA, 0.2 ms, fig. 2). Evoked potentials are recorded from the contralateral postcentral gyrus (C3', C4') and in 5 cases (roots) also from C2 against a common frontal reference (Fz). Eleven patients were operated under general anaesthesia with propofol intravenously, three patients under general anaesthesia with enflurane and two patients with isoflurane. All patients except of one with propofol had nitrous oxide (59-68 vol. %). In 38 out of 42 cases we were able to record reproducable potentials.