To the Editor:
We read with interest the article by Kaufman et al.1
on the development of phrenic neuropathies after intraoperative scalene block. Although these cases are well described and instructive in the role of adhesions contributing to phrenic neuropathy, this is but one potential mechanism by which inflammation may contribute to the development of perioperative neuropathies. Local or generalized inflammation of the microvessels in nerve and subsequent ischemic injury are observed in a variety of neuropathic conditions, including diabetic and nondiabetic asymmetrical neuropathies2
and idiopathic and hereditary brachial plexus neuropathy,4
the latter of which is also reported to have a predilection for the phrenic nerve. These conditions may first become symptomatic perioperatively and can have significant medicolegal implications.
We have previously reported on patients who developed a variety of neuropathies, including phrenic neuropathy, after surgeries.5
In 21 of the 33 patients, a biopsy of the superficial sensory nerves distant from the site of surgery was done, and we observed abnormal amounts of nerve inflammation in all of these and signs of nerve microvasculitis in 71% of these. Our study found that immunotherapy with steroids often can improve the pain and weakness associated with these neuropathies. In summary, although Kaufman et al.
have reported localized adhesions as one important cause of postsurgical phrenic neuropathy, clinicians should consider diverse potential etiologies of postsurgical neuropathies, including nerve microvasculitis.
This work was supported by the National Institutes of Health, CA169443 (to Dr. Staff), Bethesda, Maryland.
The authors declare no competing interests.
Nathan P. Staff, M.D., Ph.D., P. James B. Dyck, M.D., Mark A. Warner, M.D.
Mayo Clinic, Rochester, Minnesota (N.P.S.). firstname.lastname@example.org
1. Kaufman MR, Elkwood AI, Rose MI, Patel T, Ashinoff R, Fields R, Brown D. Surgical treatment of permanent diaphragm paralysis after interscalene nerve block for shoulder surgery. ANESTHESIOLOGY. 2013;119:484–7
2. Dyck PJ, Engelstad J, Norell J, Dyck PJ. Microvasculitis in non-diabetic lumbosacral radiculoplexus neuropathy (LSRPN): Similarity to the diabetic variety (DLSRPN). J Neuropathol Exp Neurol. 2000;59:525–38
3. Dyck PJ, Norell JE, Dyck PJ. Non-diabetic lumbosacral radiculoplexus neuropathy: Natural history, outcome and comparison with the diabetic variety. Brain. 2001;124(Pt 6):1197–207
4. van Alfen N, van Engelen BG. The clinical spectrum of neuralgic amyotrophy in 246 cases. Brain. 2006;129(Pt 2):438–50
5. Staff NP, Engelstad J, Klein CJ, Amrami KK, Spinner RJ, Dyck PJ, Warner MA, Warner ME, Dyck PJ. Post-surgical inflammatory neuropathy. Brain. 2010;133:2866–80
© 2014 American Society of Anesthesiologists, Inc.