INFARCTION OF THE SPINAL CORD: AN AVOIDABLE COMPLICATION OF THE INTERSCALENE BLOCK

Abstract

We describe seven cases of permanent neurological damage following interscalene block used in post-operative analgesia after operations at the shoulder. MRI, Nerve Conduction Studies and Quantitative assessments of function confirmed that in all there was infarction of the anterior spinal cord, resulting in a spinothalamic and corticospinal tract defect especially at segments C7, C8 and T1. We think that these lesions were caused by injury to radicular arteries. Domisse has demonstrated the anatomy of the radicular vessels joining the anterior spinal artery to supply the anterior two thirds of the cord. They are branches of the vertebral, ascending cervical and deep cervical arteries which pass through the inter-vertebral foramina with the C7, C8 and T1 roots predominantly. Chakravorty has shown that radicular vessels contribute to the blood supply of the lower cervical cord. Injury to them can cause ischaemia, leading to Anterior Spinal Artery Syndrome. We suggest tamponade of the radicular vessels by infusion of fluid under pressure deep to the prevertebral fascia as the main mechanism but neurotoxicity and vasospasm can be other possible explanations.

In a second group there was an additional interference with the vertebral artery presenting with transient bulbar and cranial nerve symptoms. We had 2 patients with such combined lesions. Complications of interscalene blocks are well documented but most are reversible and transient. In our cases the damage has been permanent and disabling. The innervation of the gleno-humeral joint is largely through the 4th, 5th and 6th cervical nerves and we suggest more appropriate placing of the blockade should be adapted and use of this technique for post-operative analgesia should be abandoned.