# Surgical treatment of post-surgical mastectomy pain utilizing the regenerative peripheral nerve interface (RPNI)

> **NIH NIH R21** · UNIVERSITY OF MICHIGAN AT ANN ARBOR · 2020 · $203,580

## Abstract

PROJECT SUMMARY
Up to 40% of patients who undergo mastectomy suffer from chronic pain, defined as pain lasting greater than 3
months. Nevertheless, mastectomy remains a mainstay of treatment for over 25% of breast cancer patients,
necessitating novel, definitive solutions for chronic pain. Previous studies have documented that breast cancer
patients with post-surgical pain experience worse quality-of-life with respect to physical and psychological well-
being. Over 10% of opioid naïve patients who undergo breast cancer surgery require opioids for pain relief at
least three months after surgery. Current pharmacologic strategies including non-steroidal anti-inflammatory
drugs (NSAIDs) and neuropathic drugs (e.g. gabapentin or amitriptyline) are often insufficient due to adverse
effects, incomplete pain relief, and poor patient compliance. Several reports have demonstrated that cutaneous
nerve injury substantially contributes to post-mastectomy pain. Altered sensation, including `pins and needles'
sensation and/or shock-like, burning, or stabbing pain in the known distribution of chest wall sensory nerves
suggest a neuropathic etiology. A strategy which addresses the underlying nerve injury would offer an
opportunity to definitively treat chronic post-mastectomy pain. The regenerative peripheral nerve interface
(RPNI) has emerged as a novel strategy to treat neuromas in peripheral nerves. The RPNI consists of the
residual peripheral nerve end implanted in a muscle graft, following surgical resection of the injured terminal
nerve portion (neuroma). The muscle graft is separated from its native nerve input, leaving neuromuscular
junctions open for ingrowth of nerve fibers from the implanted nerve; animal studies show that this provides a
physiologic end-organ for the implanted nerve without neuroma recurrence. We have performed RPNIs to treat
painful neuromas associated with limb amputation, with significant reductions in patient-reported pain.
Recently, we have performed RPNIs to treat intercostal neuromas in patients with chronic post-mastectomy
pain. Limited follow-up suggests that these patients experience substantial improvement in their pain, although
formal evaluation is required. Our central hypothesis is that intercostal nerve RPNI surgery significantly
reduces chronic post-mastectomy pain without neuroma recurrence. We will employ a cross-over study
design assess the efficacy of RPNI surgery for intercostal neuroma while optimizing patient enrollment.
Aim 1: To demonstrate the efficacy of RPNI surgery to reduce post-mastectomy pain and opioid
consumption. We will obtain patient-reported outcomes (PRO's), using previously validated tools, to measure
the effect of RPNI surgery on post-mastectomy pain and opioid use in this pilot clinical study.
Aim 2: To demonstrate absence of neuroma recurrence in post-mastectomy patients after intercostal
RPNI surgery. Neuroma recurrence in patients treated with intercostal RPNI will be evaluated using physi...

## Key facts

- **NIH application ID:** 10009297
- **Project number:** 5R21CA234760-02
- **Recipient organization:** UNIVERSITY OF MICHIGAN AT ANN ARBOR
- **Principal Investigator:** David Lawrence Brown
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $203,580
- **Award type:** 5
- **Project period:** 2019-09-05 → 2023-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10009297

## Citation

> US National Institutes of Health, RePORTER application 10009297, Surgical treatment of post-surgical mastectomy pain utilizing the regenerative peripheral nerve interface (RPNI) (5R21CA234760-02). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10009297. Licensed CC0.

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