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Incidence and etiology of postoperative neurological symptoms after peripheral nerve block: a retrospective cohort study
  1. Karen K Lam1,
  2. Neilesh Soneji1,
  3. Hans Katzberg2,
  4. Li Xu1,
  5. Ki Jinn Chin1,
  6. Arun Prasad1,
  7. Vincent Chan1,
  8. Ahtsham Niazi1 and
  9. Anahi Perlas1
  1. 1Anesthesia and Pain Management, Toronto Western Hospital, Toronto, Ontario, Canada
  2. 2Medicine, Neurology Program, Toronto Western Hospital, Toronto, ON, Canada
  1. Correspondence to Dr Anahi Perlas, Anesthesia and Pain Management, Toronto Western Hospital, Toronto, ON M5T2S8, Canada; anahi.perlas{at}


Background Nerve injury from peripheral nerve block (PNB) is an uncommon but potentially serious complication. We present a retrospective cohort study to evaluate the incidence and etiology of new postoperative neurological symptoms after surgery and regional anesthesia.

Methods We performed a retrospective cohort study of all PNBs performed on elective orthopedic and plastic surgical patients over 6 years (2011–2017). We collected patient and surgical data, results of neurophysiological and imaging tests, neurology and chronic pain consultations, etiology and outcome for patients with prolonged neurological symptoms (lasting ≥10 days).

Results A total of 26 251 PNBs were performed in 19 219 patients during the study period. Transient postoperative neurological symptoms (<10 days) were reported by 14.4% (95% CI 13.1% to 15.7%) of patients who were reached by telephone follow-up. Prolonged postoperative neurological symptoms (≥10 days) were identified and investigated in 20 cases (1:1000, 95% CI 0.6 to 1.6). Of these 20 cases, three (0.2:1000, 95% CI 0.04 to 0.5) were deemed to be block related, seven related to surgical causes, three due to musculoskeletal causes or pain syndromes, one was suspected of having an inflammatory etiology and six remained of undetermined etiology. Of those who completed follow-up, 56% had full recovery of their symptoms with the remaining having partial recovery.

Conclusion This retrospective review of 19 219 patients receiving PNBs for anesthesia or analgesia suggests that determining the etiology and causative factors of postoperative neurological symptoms is a complex, often challenging process that requires a multidisciplinary approach. We suggest a classification of cases based on the etiology. A most likely cause was identified in 70% of cases. This type of classification system can help broaden the differential diagnosis, help consider non-regional anesthesia and non-surgical causes and may be useful for clinical and research purposes.

  • brachial plexus
  • lower extremity
  • nerve injury

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  • Contributors KKKL is the principal author. She performed data collection and analysis. She wrote the first draft of the manuscript. NS is coprincipal author. He mentored KKKL throughout the process and edited the manuscript. HK advised on neurological aspects of the work-up, reviewed all files of neurological deficits, assisted in classifying and assigning diagnosis and edited the manuscript. LX conceived the study and wrote the protocol for REB approval under AP’ mentorship. KJC contributed to the analysis and edited the manuscript. AP assisted with identification of index cases, and edited the manuscript. AN assisted with data collection and identification of index cases and edited the manuscript. VC assisted with study design and edited the manuscript. AP is the senior author. She designed the study and submitted for REB approval, mentored junior authors, participated in data analysis and edited the manuscript.

  • Funding This manuscript was supported by internal departmental funds.

  • Competing interests AP has a research grant from Fisher and Paykel for an unrelated study. VC has received honoraria from Philips Healthcare.

  • Patient consent for publication Not required.

  • Ethics approval Ethics is approved by Research Ethics Board (REB) (University Health Network REB 17–5445, approved on 13 July 2017)

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement No data are available.