Thoracic outlet syndrome (TOS) occurs due to compression of the neurovascular bundle exiting the thoracic outlet, through which the brachial plexus and subclavian vessels pass. Here, we report a case of venous TOS combined with brachial neuritis, which was caused by axillary lymphadenopathy after the first dose of the BNT162b2 vaccine against coronavirus disease 2019 (COVID-19). A 17-year-old female patient presented with left upper extremity swelling and pain after inoculation with the BNT162b2 vaccine in the left deltoid muscle. Contrast-enhanced brachial plexus magnetic resonance imaging revealed severe swelling of the left axillary and subclavian lymph nodes, which lie immediately above the subclavian vein. An electrodiagnostic study revealed left brachial plexopathy, mainly involving the lower trunk with mixed demyelinating and axonal injury. The patient received intravenous steroid pulse therapy and oral steroid therapy. A follow-up examination showed complete recovery of muscle strength and function, pain, and swelling in the left upper extremity within 3 months after vaccination against COVID-19.
Thoracic outlet syndrome can occur from compression of the neurovascular bundle exiting the thoracic outlet, through which the brachial plexus and subclavian vessels locate. Entrapment of the axillary and subclavian vessels results in vascular TOS, which is subclassified into arterial and venous types [
There are a few case reports of acute brachial neuritis following coronavirus disease 2019 (COVID-19) vaccination [
A 17-year-old female presented with left upper extremity swelling and pain after inoculation with the BNT162b2 vaccine against coronavirus disease 2019 (COVID-19) in the left deltoid muscle. Pain and swelling in the upper arm started approximately 2 hours after the vaccination and spread to the lower arm and hand on the day after vaccination. However, she only observed this symptom and waited for it to subside, knowing that pain and swelling are very common side effects of mRNA vaccines. Although the swelling improved slowly, left arm weakness newly developed 2 weeks later. At that time, only hand swelling below the wrist was noticed, with a reticulated erythematous patch on the dorsum of the hand, implying problems with the peripheral circulation (
She visited the Department of Pediatrics 2 weeks after the onset of left arm weakness. A neurological examination revealed motor weakness of grade 3 to 4 in the left upper extremity based on the Medical Research Council scale (left shoulder abductor grade 3-, elbow flexor grade 3-, elbow extensor grade 4, wrist dorsiflexor grade 3-, finger abductor grade 3, and finger flexor grade 3-). She reported hypesthesia in the entire left arm and paresthesia in the left palm. Adson’s test and Wright’s test were positive, while the costoclavicular test was negative. Laboratory investigations, including complete blood count, electrolytes, creatine kinase, and lactate dehydrogenase, were within normal ranges. The results of other autoimmune-related laboratory tests, such as anti-double-stranded DNA, fluorescent antinuclear antibody, lupus anticoagulant antibody, and antiphospholipid antibody, were also unremarkable. Contrast-enhanced left brachial plexus magnetic resonance imaging (MRI) was performed 3 weeks after the onset of left arm weakness. Brachial plexus MRI revealed bilateral—yet left upper extremity predominant—lymphadenopathy, including severe swelling of the left axillary nodes and subclavian lymph nodes, which lie immediately above the subclavian vein (
A nerve conduction study (NCS) was performed 3 weeks after the onset of weakness to diagnose possible immune-mediated polyneuropathy at the Department of Rehabilitation Medicine. The latency and amplitude of the sensory nerve action potentials (SNAPs) of the bilateral median, ulnar, radial, lateral antecubital cutaneous, and medial antebrachial cutaneous nerves were symmetric (
Needle electromyography (EMG) revealed prominent denervation potentials and neuropathic motor unit action potentials (MUAPs) in the left extensor indicis, abductor pollicis brevis, and first dorsal interosseous muscles from the lower trunk (
After intravenous steroid pulse therapy for 3 days and maintenance for 4 months, a follow-up examination showed complete recovery of muscle strength in the left upper extremity, pain, and swelling within 3 months after the vaccination.
The clinical course of brachial neuritis consists of sudden, severe neuropathic pain, fast multifocal weakness, and atrophy of the upper extremities [
An electrodiagnostic study is one of the examinations for confirming brachial neuritis. Although sensory nerve conduction studies are useful for diagnosing peripheral neuropathies or brachial plexopathies, the sensory NCS is reported to be normal in 80% of patients with brachial neuritis [
The diagnosis of venous TOS requires a comprehensive consideration of the patient’s history, a physical examination, and imaging techniques [
Although brachial neuritis is usually self-limiting, the previously reported recovery rate is 36% by 1 year, 75% by 2 years, and 89% by 3 years [
In conclusion, brachial neuritis combined with an interruption of subclavian vessels and venous TOS followed by lymphadenopathy can occur after COVID-19 vaccination. Therefore, clinicians should evaluate vascular symptoms and neurological examinations to consider the possibility of combined venous TOS before confirming post-vaccine brachial neuritis if sudden weakness with dominant swelling and erythema occurs after a vaccination. Although follow-up electrodiagnostic studies and MRI were not conducted in this study, which would have provided more accurate evidence of the patient’s full recovery, this case report suggests the possibility of different pathomechanisms corresponding to diverse prognoses and recovery potentials of brachial neuritis after vaccination.
No potential conflict of interest relevant to this article was reported.
A reticulated erythematous patch (arrows) and swelling on the dorsum of the left hand 1 month after a vaccine inoculation that was administered in the ipsilateral, left deltoid muscle.
(A) Coronal view of brachial plexus magnetic resonance imaging (MRI) demonstrating an enlarged subclavian lymph node (straight arrow) compressing the subclavian vein (white arrowhead). An enlarged lymph node (curved arrow) near the left brachial plexus (empty arrowhead) is also apparent, but not compressing the brachial plexus. (B) Transverse view of brachial plexus MRI imaging demonstrating the relationship of the subclavian vein (white arrowhead) with the enlarged subclavian lymph node (straight arrow) and the brachial plexus (empty arrowhead).
(A) Abnormal spontaneous activities in the left first dorsal interosseous muscle. (B) Abnormal spontaneous activities in the left abductor pollicis brevis muscle. EMG, electromyography.
Nerve Conduction Study Results
Nerve (recording) | Stimulation | Latency (ms) |
Amplitude |
Duration (ms) |
Area (mV·ms ) |
Conduction velocity (m/s) |
|||||
---|---|---|---|---|---|---|---|---|---|---|---|
Right | Left | Right | Left | Right | Left | Right | Left | Right | Left | ||
Motor NCS | |||||||||||
Median (APB) | Wrist | 3.07 | 3.54 | 9.9 | 9.6 | 21.3 | 20.16 | 52.2 | 60.6 | ||
Elbow | 6.67 | 7.14 | 9.9 | 9.7 | 21.25 | 20.99 | 50.1 | 56.5 | 55.7 | 61.2 | |
Erb’s point | 11.93 | 9.3 | - | 21.82 | - | 52.6 | - | 71.0 | |||
Ulnar (ADM) | Wrist | 3.03 | 2.55 | 5.6 | 5.9 | 25.99 | 28.91 | 28.30 | 55.3 | ||
Below elbow | 5.89 | 5.52 | 5.4 | 5.9 | 26.2 | 28.91 | 26.90 | 47.4 | 67.8 | 64.0 | |
Above elbow | 7.5 | 7.14 | 5.3 | 5.8 | 26.3 | 29.90 | 27.40 | 53.3 | 61.9 | 61.9 | |
Axillary (deltoid) | Erb’s point | 3.07 | 3.02 | 16.9 | 14.8 | 26.2 | 31.65 | 182.80 | 189.80 | ||
Suprascapular (SST) | Erb’s point | 1.82 | 2.50 | 10.8 | 9.4 | 26.25 | 24.79 | 130.90 | 117.50 | ||
Musculocutaneous (biceps) | Erb’s point | 3.96 | 3.39 | 14.3 | 10.5 | 34.43 | 38.28 | 143.80 | 112.90 | ||
Radial (EIP) | Forearm | 2.45 | 2.76 | 5.1 | 3.8 | - | - | - | - | ||
Elbow | 5.47 | 5.99 | 4.0 | 3.1 | - | - | - | - | 59.6 | 55.7 | |
F-wave | |||||||||||
Median (APB) | Wrist | 22.50 | 22.66 | ||||||||
Ulnar (ADM) | Wrist | 24.32 | 23.44 | ||||||||
Sensory NCS | |||||||||||
Median (digit II) | Wrist | 2.29 | 2.29 | 42.4 | 43.1 | ||||||
Ulnar (digit V) | Wrist | 2.29 | 2.66 | 25.5 | 26.9 | ||||||
Radial (snuff box) | Forearm | 1.88 | 1.72 | 37.5 | 33.5 | ||||||
LAC (forearm) | Forearm | 1.20 | 1.41 | 26.7 | 29.2 | ||||||
MAC (forearm) | Forearm | 1.56 | 1.35 | 14.9 | 13.5 |
Amplitudes are measured in millivolt (mV, motor) and microvolt (μV, sensory).
NCS, nerve conduction study; APB, abductor pollicis brevis; ADM, abductor digiti minimi; SST, supraspinatus; EIP, extensor indicis proprius; LAC, lateral antebrachial cutaneous; MAC, medial antebrachial cutaneous.
Needle Electromyography Results
Muscle | IA | Spontaneous |
MUAP |
Recruitment pattern/IP | |||
---|---|---|---|---|---|---|---|
Fib/PSW | Other | Amplitude | Duration | Polyphasicity | |||
Lt. extensor indicis | Increased | 3+/3+ | None | N | N | N | Discrete |
Lt. abductor pollicis brevis | N | 4+/4+ | None | No activity | |||
Lt. first dorsal interosseous | N | 4+/4+ | None | N | N | Increased | Discrete |
Lt. biceps brachii | N | 2+/2+ | None | N | Short | Increased | Reduced |
Lt. deltoid | N | 1+/1+ | None | N | Short | N | Reduced/complete |
Lt. abductor hallucis | Increased | 0/0 | CRD (1+) | N | N | N | Complete |
Lt. vastus medialis | N | 0/0 | None | N | N | N | Discrete |
Rt. extensor indicis | Increased | 0/0 | None | N | N | N | Reduced/complete |
IA, insertional activity; Fib, fibrillation; PSW, positive sharp wave; MUAP, motor unit action potential; IP, interference pattern; Lt., left; Rt., right; N, normal; CRD, complex repetitive discharge.