All patients presented to a single institution with BPT and underwent surgical treatment between January 2010 and December 2017. The authors reviewed the medical records of all 18 patients retrospectively and collected data including the age, sex, clinical presentation, tumor characteristics, and pathology. Magnetic resonance imaging (MRI) studies were performed in all patients to evaluate tumor size, location, and characteristics.

In this study, when the BPT was located from cord level to division level, the authors applied an anterior supraclavicular approach. When the tumor was located below the cord level, the authors applied an anterior infraclavicular approach. A supra&infraclavicular approach was used in case tumor was large enough to need both approaches due to clavicle. The patient was positioned supine with a roll under the ipsilateral shoulder and the head turned 30 degrees toward the opposite side. For a supraclavicular approach, a V-shaped skin incision was made, with one side parallel to the clavicle and one side parallel to the sternocleidomastoid muscle (SCM). When the platysma was exposed, it was incised, with dissection along the lateral border of the SCM (Fig. 1A). When the omohyoid muscle is seen crossing obliquely, it can be retracted or cut (Fig. 1B). After the omohyoid muscle was cut, the phrenic nerve could be visualized in front of the anterior scalene muscle. This nerve should be preserved (Fig. 1C). The brachial plexus was somewhat exposed, but because the BPT was large and crossed the clavicle, an infraclavicular approach and clavicle resection were reqired. An additional incision was made over the deltoid-pectoral groove. After dissection of the deltoid muscle and the pectoralis major muscle, the pectoralis minor muscle and its origin at the coracoid process were encountered. With retraction of the pectoralis minor muscle upward and downward, the cord level of the brachial plexus was visible (Fig. 1D). The entire tumor was exposed, displacing the normal elements of the nerve axon to one side, and cautious dissection was performed. The tumor was removed en bloc (Fig. 1E and F). After BPT removal, the entire brachial plexus anatomy could be seen (Fig. 1G). The encapsulated tumor had high vascularity, yellowish color, and hardness (Fig. 1H).

The authors checked preoperative electromyography (EMG) to measure baseline evoked potential. In general anesthesia, short-acting muscle relaxants (rocuronium bromide) are given for intubation, since then, muscle relaxants have not been injected. Also, the surgeon confirmed recovery from effect of the muscle relaxants by using stimulus testing. Multiple EMG needles are placed into the muscles which the surgeon want to examined. The authors usually use motor evoked potential (mEP), somatosensory evoked potential (ssEP) and direct nerve stimulation for brachial plexus tumor. After stimulation of the peripheral nerve at the upper extremity, ssEP was recorded from the transcranial electrode. The stimulus was given automatically every 15 minutes (single stimuli of 200 μsec duration, intensity 25 mA, stimulation rate 2.31 Hz). mEPs were evoked by using transcranial electrical simulation with multi-pulse or train stimulation technique, and recorded from the target muscle. Direct nerve stimulation was used to make sure when the structure was uncertain whether it was nerve or not, by bipolar stimulation forceps intraoperatively. It would help to decide whether suspicious neural structure could be sacrificed or should be preserved.

For statistical analysis, we used the R statistical software program (R version 3.2.4, Comprehensive R Archive Network, http://cran.r-project.org). Eighteen cases of brachial plexus tumor were divided into two groups by its size. ‘Large group’ was defined as a tumor size greater than 3 cm, and ‘Small group’ was defined as a tumor size less than 3 cm. Mann-Whitney U test and Fisher’s exact test was performed to determine statistical significance with large group and small group, and p ≤0.05 was set as the threshold. The authors analyzed also, characters of brachial plexus tumor according to tumor location and surgical approach. All tumors were classified into three groups by its location as follow : infraclavicular group, supraclavicular group, and supra & infraclavicular group.

A total 18 of patients with BPTs were enrolled. The study included 8 men (44.4%) and 10 women (55.6%), and the median age of the population was 51 years (interquartile range [IQR], 24–80 years). Demographic data and characteristics of the patients are detailed in Table 1. Almost all patients with BPT (17 patients, 94.4%) had at least one symptom. The most common symptom was a palpable mass, which was present in 17 patients (94.4%). The next most common symptoms were localized tenderness (nine patients, 55.6%), sensory alterations (eight patients, 44.4%), and motor weakness (four patients, 22.2%). Sensory alterations included anesthesia, hypesthesia, hyperesthesia, and dysesthesia. Clinical symptoms of the patients are detailed in Table 2.

Eight patients presented with right-sided BPT (44.4%), and 10 patients (55.6%) had left-sided BPT. In this study, the aouthos categorized BPT to three groups. First, benign peripheral nerve sheath tumor (PNST), including schwannoma and neurofibroma, was present in 15 patients (83.3%). Second, malignant PNST was present in one patient (5.6%). Third, benign tumors of non-neural sheath origin (neurogenic cyst) were present in one patient (5.6%). Metastatic tumor, including papillary carcinoma, was present in one patient (5.6%). The most common location was trunk level in 10 cases (55.6%). A large tumor may occupy two or more levels. The summary of all patients is presented in Table 3.

To analysis character of brachial plexus tumor according to size, all tumors were classified into two groups. There were no statistically significant differences in sex, right-left, pathology, and approach between large group and small group. However, the mean age of the large group was 45 years, and the mean age of the small group was 64 years. It is tend to occur larger tumor in young age with statistical significance (p=0.046). It is presented in Table 4. Also, the authors analyzed relationship between tumor location and tumor characteristic parameters such as age, size, right-left, and pathology. There were no statistically significant differences and it is presented in Table 5.

Gross tumor removal was possible in 17 of the 18 patients. The mean postoperative follow-up period was 19.8 months. Localized tenderness was improved after surgery in nine out of nine patients. Hypesthesia and motor weakness were also improved after surgery, but the improvement of these symptoms took several weeks to several months. Hypesthesia and motor weakness newly occurred in one patient because surgical dissection was difficult owing to severe adhesion. Motor weakness of shoulder abduction and elbow flexion with a motor grade 4 occurred immediate postoperatively, but gradually improved, and it was recovered after 2 months from surgery.

Fifty seven years old male patient who complained of a left supraclavicular area palpable mass was referred from department of head and neck surgery. Brachial plexus MRI revealed lobulated contrast enhancing large mass in left trunk to divisional portion. The tumor was suspected as malignancy, because of lymph node enlargement and adhesion with nearby tissue, vessel, or nerve (Fig. 2A). Surgical resection by supraclavicular approach with IONM was scheduled. Subtotal tumor removal was achieved without any postoperative complication. Postoperative MRI showed subtotal resection was achieved (Fig. 2B). Pathologic results revealed that the tumor consisted with neurofibrosarcoma. However, the patient complained of radiating pain on left upper extremity again after 6 months from surgery. Unfortunately, the brachial plexus MR showed recurred neurofibrosarcoma (Fig. 2C). The authors suggested revision surgery, but the patient refused and transferred to another hospital.

The case of a 45-year-old male who presented with a tingling sensation in the right finger and a palpable mass in the right supraclavicular area visited to department of neurosugery. Brachial plexus MRI revealed a well-defined contrast-enhancing multilobulated large mass extending from the C7 nerve root to the middle trunk (Fig. 3). EMG result showed findings suggestive of plexopathy of the right lower brachial plexus. Surgical resection with a supra- and infraclavicular approach with IONM was scheduled. The pathologic study showed biphasic pathologic pattern which implied schwannoma (Fig. 4). Six months after the surgery, the patient reported no definite neurological deficits, and his initial presenting symptom, a tingling sensation of right finger, had disappeared.