Keywords
Brachial Plexus - Neural Sheath Tumors - Schwannoma
Palavras-chave
Plexo Braquial - Tumores de Bainha Neural - Schwanoma
Introduction
Schwannomas are mostly benign and solitary tumors that originate from Schwann cells.[1] They are more frequent in adults over 40 and more frequent in females.[2]
[3] They are usually found on the peripheral nerves of the upper limbs and neck. They
can also reach the spinal nerve roots, being extra axial and extradural masses that
grow through the intervertebral foramen, compressing the nerves.[4] Macroscopically, they appear as rounded masses with a smooth surface.[5]
Schwannomas rarely affect the brachial plexus, accounting for approximately 5% of
all cases of schwannomas.[6]
[7] Since brachial plexus schwannomas are a rare entity and, due to the brachial plexus
anatomic complexity, schwannomas in this region present a challenge for surgeons.
The objective of this article is to describe a case report of a brachial plexus schwannoma
in a hospital located in the Northeast of Brazil.
Case Report
We present the case of a 49-year-old male patient who complained of pain resulting
from the appearance of a left anterior cervical bulging one and a half years ago,
with progressive growth ([Fig. 1]). On physical examination, he had a Medical Research Council (MRC) score of 3 in
left arm abduction and paresthesia in the left lateral forearm and arm. He denied
other motor or sensory alterations. On ultrasonography (US), there were no changes
in vessel caliber. On magnetic resonance imaging (MRI), the lesion arises from the
C4-C5 junction, measuring 5.9 × 5.4 × 5.5 cm ([Fig. 2]). Electroneuromyography showed chronic pre-ganglionic involvement of C5 to C7 bilaterally.
Fine-needle aspiration biopsy (FNAB) revealed the proliferation of spindle cells without
atypia, suggestive of a benign mesenchymal neoplasm, schwannoma (neurilemoma).
Fig. 1 Left anterior cervical bulging with progressive growth.
Fig. 2 Magnetic Resonance Imaging showing left brachial plexus schwannoma in axial view
(a) and coronal view (b).
With the patient in dorsal decubitus, a left cervicotomy was performed with a horizontal
incision at the level of the laryngeal eminence. The platysma muscle was incised,
and the carotid sheath was exposed. The carotid sheath was then bluntly dissected
to isolate the vascular complex with the vagus nerve. The phrenic nerve from the lesion
on the left was identified and isolated using neurostimulation. Brachial plexus microsurgery
was performed with neurolysis exploration and interfascicular grafts. Tumor lesions
were debulked for situreduction, peripheral nerve tumors were excised, and the surgical
site was closed by planes with reinsertion of the sternocleidomastoid muscle ([Figs. 3] and [4]).
Fig. 3 Intraoperative view of left brachial plexus schwannoma.
Fig. 4 Brachial plexus schwannoma after complete resection.
In macroscopy, the material exhibited irregular tissue formation, with a brownish
to tan color, and elastic consistency, measuring 3.8 × 3.2 × 2.0 cm and weighing 67g.
Other irregular tissue fragments were also removed, measuring 2.2 × 1.5 × 0.8 cm,
and the aggregate measured 5.0 × 4.5 cm. Microscopically, compatibility with Grade
1 WHO Schwannoma was observed, with signs of hemorrhage at various stages of resolution.
In the postoperative period, the patient-maintained muscle weakness, particularly
in arm abduction, scoring 3 on the MRC scale. Six months after surgery, the patient
reported persistent intermittent pain, described as squeezing and burning with paresthesia,
radiating to the arm. He reported peaks of intensity and variations in thermal sensation
in the left arm and forearm. He denied limitation of movement. He was taking 75mg
of pregabalin and 3mg of eszopiclone and was referred to improvement of these sensory
alterations.
Discussion
Tumors of the brachial plexus are very rare. Schwannoma is one of the types of brachial
plexus tumor characterized as a benign primary neoplasm. Considering it is a subtype
of brachial plexus tumor, it is an even rarer lesion in this topography.[6]
[8]
[9] The clinical presentation of brachial plexus tumors may vary according to their
location, extension, neural elements involved, and pathology.[2]
Symptoms can be caused by direct nerve invasion, infiltration of surrounding tissues,
or local mass effect.[2] Schwannomas in this region usually present as a local slow-growing mass but in some
cases present with symptoms of nerve compression.[10] According to Go et al. the most common presenting symptom was growing mass (95.4%), sensory deficit (54.5%),
motor deficit (40.9%), direct tenderness and pain (27.2%), followed by included radiating
pain (22.7%).[2]
The surgical approach for treatment depends on where the tumor is located. Brachial
plexus lesions with progressive growth tend to be managed surgically. Lesions involving
roots and trunks are commonly treated with an anterior supraclavicular approach as
observed in the present case. The lower tumors involving cords and terminal nerves
require an anterior infraclavicular approach, with or without a section of the clavicle.[2]
Conclusion
Brachial plexus schwannoma is a rare benign tumor. This diagnosis hypothesis should
be considered in patients presenting progressive neck bulging in inspection during
physical examination. This is an easy and cheap method of suspicion that can be used
by health professionals. MRI is one of the most common supplementary radiological
exams used to diagnose brachial plexus tumors. Patients with progressive neck lesions
and cervical root involvements tend to be managed surgically with a supraclavicular
approach, as shown in this case.
