Effectiveness of the histamine test for diagnosing root avulsion in patients with traumatic brachial plexus injury

Abstract

Objectives: Making the diagnosis of root avulsion in traumatic brachial plexus injuries is important but sometimes difficult. The histamine test for differentiating between pre- and post-ganglionic lesions is a simple, fast and low-cost procedure. We conducted a study on patients with traumatic brachial plexus injury in order to evaluate the effectiveness of this test. Patients and methods: A total of 60 patients were initially evaluated. The subjects underwent clinical examination, myelo-CT and myelo-MRI, as well as the histamine test. The latter was applied to dermatomes C5 to T1, and occurrences of secondary neurogenic erythema were noted. The results were compared with surgical and imaging findings. Results: No statistical significance could be found for C5 and C6 roots, compared with surgical evaluation. The results for C5 showed that this may be useful for determining avulsion. Although significant results were found between the histamine test and imaging findings for all roots except for C6, the specificity of 0% for C8 and T1 is not helpful in clinical practice. Conclusion: Histamine test seems to be useful for C5 root assessment, since neurophysiological assessment of that root is difficult. There was no significance for C6 root and disappointing specificity for the C8-T1 level. Keywords: Brachial plexus injuries, Nerve root avulsion, Neurogenic inflammation