Lyme Disease Brachial Plexopathy: Arm Weakness and Radicular Pain

Lyme disease brachial plexopathy can present as progressive arm weakness, neck pain, and shock-like pains radiating from the shoulders. A 76-year-old man developed left arm weakness following what he believed was a mosquito bite. He was initially treated for presumed cellulitis with temporary improvement. However, he returned 24 days later with bilateral paroxysmal “shock-like” pains and worsening weakness. MRI later revealed meningoradiculitis involving the brachial plexus and spinal cord, and Lyme testing confirmed neuroborreliosis requiring IV ceftriaxone for recovery.

Initial Presentation: Arm Weakness and Neck Pain

In their article “Early Lyme neuroborreliosis manifesting as brachial plexopathy and meningitis in Northwestern Ontario, Canada,” Gu and colleagues describe a case of Lyme disease presenting as brachial plexopathy and meningitis.

The 76-year-old man was initially admitted to the hospital with left arm weakness and neck pain. He also had a 3-day history of body aches and headaches.

He reported having what he believed to be a mosquito bite, which became increasingly red and swollen. But he did not notice any ticks attached to his skin.

The combination of arm weakness, neck pain, body aches, and headaches after a suspected insect bite should have raised suspicion for tick-borne infection. But without recognizing the bite as a tick, the diagnosis was missed.

Lyme Disease Brachial Plexopathy Explained

Brachial plexopathy is a form of peripheral neuropathy which occurs when there is damage to the brachial plexus. This is a group of nerves that run from the lower neck through the upper shoulder area.

The brachial plexus consists of nerve roots C5-T1 that merge and divide to form the nerves supplying the arm, shoulder, and hand. Damage to these nerves causes:

• Weakness in shoulder, arm, or hand muscles
• Pain radiating from neck or shoulder down the arm
• Numbness or tingling in affected areas
• Loss of reflexes
• Muscle atrophy if chronic

Causes include trauma, radiation, tumors, autoimmune disease, and infection — including Lyme disease.

Misdiagnosed as Cellulitis

A diagnosis of purulent cellulitis was made, and he was prescribed a 7-day course of cephalexin. His symptoms resolved.

The red, swollen “bite” was interpreted as cellulitis (skin infection), and cephalexin was prescribed. The temporary improvement likely reflected either modest antibiotic activity against Borrelia or natural fluctuation in symptoms as the infection disseminated.

Return 24 Days Later: Shock-Like Pains

However, 24 days later he returned to the emergency department complaining of a mild headache, which he had for several days, along with “bilateral, paroxysmal ‘shock-like’ pains radiating from his shoulders to his arms and chest.”

He was discharged pending test results.

The shock-like pains represent radiculitis — nerve root inflammation causing sudden, electric, stabbing pains along the dermatome. This is a hallmark feature of neuroborreliosis.

Progressive Arm Weakness

Over the next few days, the man developed additional weakness in his left arm and hand. Again, he was discharged and awaited further test results.

Five days later, he returned with worsening symptoms including increased arm weakness, neck pain, and night sweats.

The progressive weakness despite antibiotics suggested inadequate therapy. Cephalexin does not penetrate the central nervous system sufficiently to treat neuroborreliosis.

MRI Reveals Polyradiculitis

Test results showed “increased signal uptake along the ventral aspect of the spinal cord at T3 and along the left brachial plexus, which was felt to be in keeping with polyradiculitis,” the authors wrote.

Lyme disease testing was positive by both ELISA and Western blot.

The MRI findings confirmed inflammation along multiple nerve roots affecting the brachial plexus and thoracic spinal cord.

Diagnosis and Treatment

“The patient was diagnosed with meningoradiculitis as a manifestation of early Lyme neuroborreliosis” and began treatment with IV ceftriaxone.

Over the following year he experienced gradual improvement and eventual complete recovery in muscle strength and sensation.

Why Lyme Disease Causes Brachial Plexopathy

Brachial plexopathy from Lyme disease occurs when Borrelia organisms invade nerve roots in the cervical and upper thoracic spine.

Possible mechanisms include:

• Direct spirochetal invasion
• Inflammatory immune response
• Meningeal spread through cerebrospinal fluid
• Nerve root swelling and compression
• Demyelination affecting nerve conduction

The result may include pain, weakness, sensory loss, and reflex changes in the affected arm.

The Diagnostic Challenge

This case involved several missed opportunities for diagnosis.

Symptoms progressed for more than one month before Lyme disease was considered.

Without recognizing the insect bite as a tick bite, Lyme disease was not initially included in the differential diagnosis.

Clinical Perspective

This case highlights how Lyme disease brachial plexopathy may be misdiagnosed when physicians do not recognize the neurologic pattern.

Shock-like radicular pain, progressive weakness, and meningitis symptoms should prompt evaluation for neuroborreliosis, even if a tick bite was not recognized.

Authors’ Conclusions

“A history of erythema migrans rash or black-legged tick bite may go unrecognized. Therefore, patients with new cranial neuropathy, painful radiculitis, or aseptic meningitis who present in a Lyme endemic area should be evaluated for early Lyme neuroborreliosis.”

Frequently Asked Questions

Can Lyme disease cause brachial plexopathy?

Yes. Lyme disease brachial plexopathy occurs when infection affects nerve roots in the cervical spine, causing inflammatory radiculoneuritis.

What are shock-like pains in Lyme disease?

These electric or stabbing pains result from nerve root inflammation and are common in neuroborreliosis.

Can cellulitis antibiotics treat Lyme disease?

Some antibiotics may temporarily improve symptoms but may not adequately treat neurologic Lyme disease.

How long does recovery take?

Neurologic recovery can take months to a year after appropriate antibiotic treatment.