Anatomical variants of the intercostobrachial nerve encountered during axillary dissection

Anatomical variants of the intercostobrachial nerve and its preservation during surgery, a systematic review and meta-analysis

BACKGROUND

The anatomic variants of the intercostobrachial nerve (ICBN) represent a potential risk of injuries during surgical procedure such as axillary lymph node dissection and sentinel lymph node biopsy in breast cancer and melanoma patients. The aim of this systematic review and meta-analysis was to investigate the different origins and branching patterns of the intercostobrachial nerve also providing an analysis of the prevalence, through the analysis of the literature available up to September 2023.

MATERIALS AND METHODS

The protocol for this study was registered on PROSPERO (ID: CRD42023447932), an international prospective database for reviews. The PRISMA guideline was respected throughout the meta-analysis. A systematic literature search was performed using PubMed, Scopus and Web of Science. A search was performed in grey literature through google.

RESULTS

We included a total of 23 articles (1,883 patients). The prevalence of the ICBN in the axillae was 98.94%. No significant differences in prevalence were observed during the analysis of geographic subgroups or by study type (cadaveric dissections and in intraoperative dissections). Only five studies of the 23 studies reported prevalence of less than 100%. Overall, the PPE was 99.2% with 95% Cis of 98.5% and 99.7%. As expected from the near constant variance estimates, the heterogeneity was low, I2 = 44.3% (95% CI 8.9%-65.9%), Q = 39.48, p = .012. When disaggregated by evaluation type, the difference in PPEs between evaluation types was negligible. For cadaveric dissection, the PPE was 99.7% (95% CI 99.1%-100.0%) compared to 99.0% (95% CI 98.1%-99.7%).

CONCLUSIONS

The prevalence of ICBN variants was very high. The dissection of the ICBN during axillary lymph-node harvesting, increases the risk of sensory disturbance. The preservation of the ICBN does not modify the oncological radicality in axillary dissection for patients with cutaneous metastatic melanoma or breast cancer. Therefore, we recommend to operate on these patients in high volume center to reduce post-procedural pain and paresthesia associated with a lack of ICBN variants recognition.

From Cadaveric Dissection to the Operating Room: A Unilateral Double Intercostobrachial Nerve and the Implications in Axillary Lymph Node Dissection

There are multiple treatment options for breast cancer (BC), including lumpectomy, chemo- and radiotherapy, complete mastectomy, and, when indicated, an axillary lymph node dissection. Such node dissections commonly lead the surgeon to encounter the intercostobrachial nerve (ICBN), which, if injured, leads to significant postoperative numbness of the upper arm. To assist in identifying the ICBN, we report a unilateral variation of a dual ICBN. The first ICBN (ICBN I) originates from the second intercostal space, as classically described in human anatomy. On the contrary, the second ICBN (ICBN II) originates from the second and third intercostal spaces. The anatomical knowledge of ICBN origin and its variations are crucial for axillary lymph node dissection in BC and other surgical interventions that involve the axillary region (e.g., regional nerve blocks). An iatrogenic injury of the ICBN has been associated with postoperative pain, paresthesia, and loss of upper extremity sensation in the dermatome supplied by this nerve. Therefore, maintaining the integrity of the ICBN is a worthy goal during axillary dissections in BC patients. Increasing the awareness of ICBN variants among surgeons reduces potential injuries, which would contribute to the BC patient's quality of life.

An uncommon, unilateral motor variation of the intercostobrachial nerve

The intercostobrachial nerve (ICBN) is commonly defined as a purely sensory nerve supplying the skin of the lateral chest wall, axilla, and medial arm. However, numerous branching patterns and distributions, including motor, have been reported. This report describes an uncommon variant of the right ICBN observed in both an 86-year-old white female cadaver and a 77-year-old white male cadaver. In both cases the ICBN presented with an additional muscular branch, termed the "medial pectoral branch", piercing and therefore innervating the pectoralis major and minor muscles. Clinically, the ICBN is relevant during surgical access to the axilla and can result in sensory deficits (persistent pain/loss of sensory function) to this region following injury. However, damage to the variation observed in these cadavers may result in additional partial motor loss to pectoralis major and minor.

Intercostobrachial Nerve (ICBN) Preservation Versus Sacrifice in Axillary Dissection: Randomized Controlled Trial

OBJECTIVES

Whether to preserve or sacrifice the intercostobrachial nerves (ICBN) is a controversial issue. In this trial, we aim to assess the effects of preservation of the ICBN during axillary dissection for patients with breast cancer in terms of pain score immediately postoperatively and several hours later, need for simple analgesia and narcotics, numbness and arm swelling.

MATERIALS AND METHODS

This is a single-institution, single-surgeon randomized controlled trial where a sample of 48 patients with breast cancer, of various age groups, were allocated randomly to any of the 2; preservation or sacrifice categories. Postoperatively, patients were asked by a physician to fill a predesigned questionnaire to assess the studied items during hospitalization and after discharge.

RESULTS

Among the 48 included patients, ICBN was sacrificed in 24 patients; of which 18 patients (75%) developed numbness in the inner aspect of the arm. While in the ICBN preservation group (24 patients) only 6 patients suffered numbness (25%) with a significant P-value of 0.001. Estimated duration of surgery with ICBN preservation was 100±22.02 minutes, while it is significantly shorter in the ICBN sacrifice group (83.48±21.55). However, with regard to other variables of pain, seroma formation, need of simple analgesia and narcotics, hospital admission days and arm swelling, there was no significant difference between the 2 groups.

CONCLUSION

This study can conclude that preservation of ICBN during axillary dissection in patients with breast CA can save these patients' additional suffering from inner arm numbness. That is at the expense of surgery duration, around 20 minutes longer, for the surgeon to take his/her time in carefully dissecting the axilla properly without injuring these ICBN.

Aberrant bifurcation of intercostobrachial nerve in the axilla: A case report

Intercostobrachial nerve (ICBN) studies have been undertaken by many authors as it is a highly variable structure with numerous patterns reported worldwide. ICBN is a frequently damaged structure in Axillary Lymph Node Dissection (ALND) or mastectomy. Compression of this nerve, due to the enlargement of axillary lymph nodes from cancer breast may be presented as referred pain along the medial side of arm. Different patterns on the course and distribution of the ICBN have been described in literature. We encountered a lesser known variation of the ICBN where it pierced the second intercostal space as a single trunk and immediately divided into two branches. The putative clinical implications of this aberrant bifurcation are of value in significantly diminishing complications such as pain and sensory disturbances presenting after mastectomy and ALND. The findings of the presentation may be of use by surgeons and interventionists in approaching the area in a more precautious manner.

The intercostobrachial nerve as a sensory donor for hand reinnervation in brachial plexus reconstruction is a feasible technique and may be useful for restoring sensation

ABSTRACT Objective Few donors are available for restoration of sensibility in patients with complete brachial plexus injuries. The objective of our study was to evaluate the anatomical feasibility of using the intercostobrachial nerve (ICBN) as an axon donor to the lateral cord contribution to the median nerve (LCMN). Methods Thirty cadavers were dissected. Data of the ICBN and the LCMN were collected, including diameters, branches and distances. Results The diameters of the ICBN and the LCMN at their point of coaptation were 2.7mm and 3.7mm, respectively. The ICBN originated as a single trunk in 93.3% of the specimens and bifurcated in 73.3%. The distance between the ICBN origin and its point of coaptation to the LCMN was 54mm. All ICBNs had enough extension to reach the LCMN. Conclusion Transfer of the ICBN to the LCMN is anatomically feasible and may be useful for restoring sensation in patients with complete brachial plexus injuries.

Aberrant Cutaneous Nerve Loops in the Axilla

During routine dissection classes, conducted for first year undergraduate medical students, we encountered a rare anatomical variation in relation to the intercostobrachial nerve (ICBN). The ICBN represents the lateral undivided cutaneous branch of second intercostal nerve. In this case, the ICBN formed nerve loops with branches of the lateral cutaneous branch of the third intercostal nerve. These loops eventually gave branches that probably supplied the floor of the axilla and proximal arm. Nowadays, this ICBN is gaining clinical importance during the axillary lymph node dissections and mammary gland surgeries. Damage to the ICBN, may results in the sensory deficits in patients undergoing surgery. In our case report, ICBN was making aberrant nerve loop along with the branches from the third intercostal nerve. Knowledge regarding the origin, formation and route of ICBN is of clinical significance to axillary surgeons, radiologist and anesthesiologists.

Origin, Branching, and Communications of the Intercostobrachial Nerve: a Meta-Analysis with Implications for Mastectomy and Axillary Lymph Node Dissection in Breast Cancer

The intercostobrachial nerve (ICBN), which usually originates from the lateral cutaneous branch of the second intercostal nerve, innervates areas of the axilla, lateral chest, and medial arm. It is at risk for injury during operative procedures that are often used in the management of breast cancer and such injury has been associated with postoperative sensory loss and neuropathic pain, decreasing the quality of life. PubMed, Excerpta Medica Database (EMBASE), ScienceDirect, Google Scholar, China National Knowledge Infrastructure (CNKI), Scientific Electronic Library Online (SciELO), Biosciences Information Service (BIOSIS), and Web of Science were searched comprehensively. Data concerning the prevalence, branching, origin and communications of the ICBN were extracted and pooled into a meta-analysis. A total of 16 studies (1,567 axillas) reported data indicating that the ICBN was present in 98.4% of person. It most often (90.6%) originated from fibers at the T2 spinal level and commonly coursed in two branching patterns: as a single trunk in 47.0% of cases and as a bifurcating pattern in 42.2%. In the latter cases, the bifurcation was usually unequal (63.4%). Additionally, the ICBN presented with anastomosing communication to the brachial plexus in 41.3% of cases. The ICBN is a prevalent and variable structure at significant risk for injury during operative procedures of the axilla. In view of the postoperative pain and paresthesia experienced by patients following injury, surgeons need to exercise caution and aim to preserve the ICBN when possible. Ultimately, careful dissection and knowledge of ICBN anatomy could allow postoperative complications to be reduced and patient's quality of life increased.

Peripheral communications of intercostobrachial nerve Peripheral communications of the intercostobrachial nerve in relation to the alar thoracic artery

The intercostobrachial nerve (ICBN) is often encountered during axillary dissection for axillary lymph node dissection (ALND) for diagnostic and therapeutic surgery for mastectomy. The present report is a case observed in the Department of Anatomy at Vardhman Mahavir Medical College, Delhi during routine dissection of the upper extremity of a male cadaver for first year undergraduate medical students. On the right side, the medial cord of brachial plexus gave two medial cutaneous nerves of arm. Both the nerves were seen communicating with the branches of the ICBN. The ICBN and one of its branches were surrounding the termination of an alar thoracic artery. These peripheral neural connections of the ICBN with the branches of the medial cord can be a cause of sensory impairment during axillary procedures done for mastectomy or exploration of long thoracic nerves. The alar thoracic artery found in relation to the ICBN could further be a cause of vascular complications during such procedures.

Intercostobrachial nerve handling and pain after axillary lymph node dissection for breast cancer

BACKGROUND

Moderate to severe pain in the first week after axillary lymph node dissection (ALND) for breast cancer is experienced by approximately 50% of the patients. Damage to the intercostobrachial nerve (ICBN) has been proposed as a risk factor for the development of persistent pain following breast cancer surgery but with limited information on acute post-operative pain. The aim of the present study was to examine the influence of ICBN handling on pain during the first week after ALND.

METHODS

The study was part of a larger prospective cohort study on persistent pain after breast cancer treatment. Pain and sensory disturbances were assessed pre-operatively, within the first 72 h post-operatively and a week after surgery. Intraoperative handling of the nerve was recorded by the surgeon as preserved, partially preserved or sectioned.

RESULTS

One hundred forty-one patients were treated with ALND level I + II, and the ICBN could be identified in 125 (89%) patients. Of the 17 not identified, eight were stated as without any sign of the nerve and were included in analysis as sectioned. Thus, the analysis included 133 patients in which 45 (34%) of these the ICBN was preserved, 39 (29%) partially preserved and 49 (37%) sectioned. At 1 week after surgery, 104 patients (78%) reported pain, whereas 35 (26%) reported moderate to severe pain. There was no difference between the ICBN groups in pain scores or sensory disturbances measured pre-operatively compared to 1 week post-operatively.

CONCLUSION

The type of ICBN handling during ALND may not influence acute post-operative pain in the first week after surgery.

Medial pectoral pedicle is a reliable landmark for axillary lymph node dissection

BACKGROUND

The anatomical orientation of structures in the axilla has not been well studied, although it is essential for a neat and safe dissection. The objective of this study was to determine the relations between neurovascular structures in the axilla as they were encountered during axillary lymph node dissection (ALND) for breast cancer.

METHODS

This was a prospective study of 29 consecutive ALNDs accompanying either mastectomy or wide local excision. The dissections were conducted in a stepwise manner and the orientation of the structures was determined as the dissections advanced from superficial to deeper planes.

RESULTS

The medial pectoral pedicle was the most superficial neurovascular structure encountered during the dissections and was curled around the lateral border of the pectoralis minor muscle in most cases. The intercostobrachial nerve lay 1-2 cm behind and below, and the axillary vein was located 2-3 cm behind and above the pedicle. The long thoracic nerve was constantly found 2-3 cm behind the intercostobrachial nerve. The thoracodorsal nerve was always accompanied by a posterior tributary of the axillary vein.

CONCLUSION

Relations between neurovascular structures in the axilla are predictable. The medial pectoral pedicle, which is consistently found and superficially located, could be used as a landmark for ALND.

In vivo study of the surgical anatomy of the axilla

Background

Classical anatomical descriptions fail to describe variants often observed in the axilla as they are based on studies that looked at individual structures in isolation or textbooks of cadaveric dissections. The presence of variant anatomy heightens the risk of iatrogenic injury. The aim of this study was to document the nature and frequency of these anatomical variations based on in vivo peroperative surgical observations.

Methods

Detailed anatomical relationships were documented prospectively during consecutive axillary dissections. Relationships between the thoracodorsal pedicle, course of the lateral thoracic vein, presence of latissimus dorsi muscle slips, variations in axillary and angular vein anatomy, and origins and branching of the intercostobrachial nerve were recorded.

Results

Among a total of 73 axillary dissections, 43 (59 per cent) revealed at least one anatomical variant. Most notable variants included aberrant courses of the thoracodorsal nerve in ten patients (14 per cent)—three variants; lateral thoracic vein in 12 patients (16 per cent)—four variants; bifid axillary veins in ten patients (14 per cent); latissimus dorsi muscle slips in four patients (5 per cent); and variants in intercostobrachial nerve origins and branching in 26 patients (36 per cent). The angular vein, a subscapular vein tributary, was found to be a constant axillary structure.

Conclusion

Variations in axillary anatomical structures are common. Poor understanding of these variants can affect the adequacy of oncological clearance, lead to vascular injury, compromise planned microvascular procedures and result in chronic pain or numbness from nerve injury. Surgeons should be aware of the common anatomical variants to facilitate efficient and safe axillary surgery.

T2 Contributions to the Brachial Plexus

Objective:

Recent advancements in neurotization and nerve grafting procedures have led to an increasing need for knowledge of the detailed anatomy of communicating branches between peripheral nerves. Although the surgical anatomy of the axilla has been well described, little is known regarding the degree or frequency of potential contributions to or communications with the brachial plexus. The aim of our study, therefore, was to explore extrathoracic, as well as potential intrathoracic, contributions to the brachial plexus from T2.

Methods:

The anatomy of the ventral primary ramus of T2 and the second intercostal nerve, including its lateral cutaneous contribution as the intercostobrachial nerve, was examined in 75 adult human cadavers (150 axillae), with particular emphasis on the communications with the brachial plexus.

Results:

Extrathoracically, communications were observed to occur in 86% of specimens. These contributions arose variably from either the intercostobrachial nerve or one of its branches and communicated with the medial cord (35.6%), medial ante-brachial cutaneous nerve (25.5%), or posterior antebrachial cutaneous nerve (24%). Whereas the majority of specimens (68.2%) were observed to have only one extratho-racic communication, 31.7% of specimens exhibited two. Intrathoracically, communications were observed to occur in 17.3% of specimens. These communications always arose from the ventral primary ramus of T2. When combining and comparing data within individual specimens, it was observed that those axillae without an extratho-racic contribution from the intercostobrachial nerve always contained an intrathoracic communication.

Conclusion:

Based on our findings, we conclude that 100% of specimens contained a communication branch between T2 and the brachial plexus. Considering the possible implications of this data, with regards to sensory innervation of the arm and axilla, further studies in this area of research could prove extremely beneficial.

The gross anatomy of the extrathoracic course of the intercostobrachial nerve

Recent reports emphasize the importance of preserving the intercostobrachial nerve (ICBN) during surgical procedures (i.e., mastectomy, axillary clearance). However, a limited number of scientific reports explore the surgical anatomy of this nerve. We dissected 100 adult human formalin-fixed cadavers (200 axillae). In all the cadavers the ICBN was present with variant contributions from intercostal nerves T1, T2, T3, and T4. The arrangements of the ICBN were typed as I through VIII. The components of Type I (45% or 90 of our specimens) included a branch to the posterior antebrachial cutaneous nerve, a branch to the anterior and lateral parts of the axilla, a branch to the medial side of the arm, and a branch to the medial antebrachial cutaneous nerve. Type II (25%) describes the ICBN arising from T2 and giving off a branch to the brachial plexus. In Type III (10%), lateral cutaneous branches of T2 and T3 fuse as a common trunk and then split immediately after exiting the intercostal space to form an ICBN. In type IV (5%), T2 and T3 join distally to form an ICBN that ends as its terminal branches. Type V (5%): T3 joins T2 from the same intercostal space proximally, with Type VI (3%) showing a very proximal branching of the sensory terminal nerves. Type VII (5%) displayed a contribution from T3 and a branch to the brachial plexus with multiple terminating branches. A contribution from T3 and T4 and a branch to the brachial plexus with multiple branches of termination comprised Type VIII (2%).

An unusual innervation of pectoralis minor and major muscles from a branch of the intercostobrachial nerve

Variations of the branching pattern of the intercostobrachial nerve have been known to complicate dissection during mastectomy and other procedures involving the axilla. We present a unilateral case of a 73-year-old Caucasian female, in which the intercostobrachial nerve gives rise to an additional medial pectoral branch, which partially innervates the pectoralis minor muscle, as well as the abdominal head of pectoralis major muscle. Clinical consequences of such a variation may include motor losses, in addition to the commonly reported sensory losses, resulting from accidental or intentional dissection of the intercostobranchial nerve.

A standardized surgical technique for mastoscopic axillary lymph node dissection

To standardize the surgical technique for mastoscopic axillary lymph node dissection (MALND). Mastoscopic lymph node dissection was performed consistently by a group of surgeons in 316 cases of breast cancer. The mean operation time was 46.7 minutes with minimal bleeding, and the median number of lymph nodes dissected at each operation was 17.0. There were no operative complications in any case, nor did trocar implantation or tumor diffusion occurring during the mean follow-up time of 15.1 months. MALND is distinctive and practicable in operative anatomy as well as safe and convenient. The location of critical anatomy such as the intercostobrachial nerve, lateral thoracic artery, medial thoracic nerve, and thoracoepigastric vein should be clearly identified to avoid damage to them, so that is the great advantage of MALND.