What is the pathophysiology of bilateral upper extremity weakness and numbness?

From the Guidelines

Bilateral upper extremity weakness and numbness is most likely caused by a condition affecting the peripheral nervous system, such as Guillain-Barré syndrome (GBS), which should be considered as a diagnosis in patients with rapidly progressive bilateral weakness of the legs and/or arms. The pathophysiology of bilateral upper extremity weakness and numbness can be attributed to various conditions, including:

• Peripheral neuropathies, such as GBS, which is characterized by rapidly progressive bilateral weakness of the legs and/or arms, accompanied by distal paraesthesias or sensory loss, and decreased or absent reflexes 1
• Central nervous system conditions, such as cervical spinal cord compression, which can compress nerve roots or the spinal cord, leading to bilateral symptoms
• Neuromuscular junction disorders, such as myasthenia gravis, which can cause bilateral weakness and numbness
• Systemic conditions, such as rheumatoid arthritis or vasculitis, which can damage nerves through inflammation

The diagnostic workup for bilateral upper extremity weakness and numbness typically includes:

• Neurological examination to assess muscle strength, reflexes, and sensation
• Imaging studies, such as MRI of the cervical spine or brain, to rule out structural causes
• Nerve conduction studies to assess nerve function
• Blood tests to identify underlying systemic conditions

Treatment for bilateral upper extremity weakness and numbness depends on the specific diagnosis, but may include:

• Anti-inflammatory medications to reduce inflammation and swelling
• Physical therapy to improve muscle strength and function
• Surgical decompression for structural issues, such as cervical spinal cord compression
• Disease-modifying therapies for autoimmune conditions, such as GBS or multiple sclerosis 1

From the Research

Pathophysiology of Bilateral Upper Extremity Weakness and Numbness

• Bilateral upper extremity weakness and numbness can be caused by various factors, including genetic disorders 2, nerve entrapment, and autoimmune diseases such as multiple sclerosis (MS) 3.
• Nerve entrapment can occur due to trauma, compression, or other conditions, and can affect the median, ulnar, or radial nerves, leading to pain, weakness, numbness, or tingling in the upper extremity 4.
• MS is a chronic and often disabling disease that affects the central nervous system, causing symptoms such as optic neuritis, partial myelitis, sensory disturbances, and brainstem syndromes, including bilateral upper extremity weakness and numbness 3.
• The diagnosis of MS is based on a combination of clinical signs and symptoms, radiographic findings, and laboratory tests, including magnetic resonance imaging (MRI) and cerebrospinal fluid analysis 3.

Possible Causes and Risk Factors

• Genetic disorders, such as the one described in the case study 2, can cause bilateral upper extremity weakness and numbness.
• Risk factors for nerve entrapment include diabetes, smoking, alcohol consumption, rheumatoid arthritis, and hypothyroidism 4.
• MS is more common in women, and the risk of developing MS increases with higher latitudes 3.
• Other possible causes of bilateral upper extremity weakness and numbness include carpal tunnel syndrome, cubital tunnel syndrome, and radial tunnel syndrome 4.

Treatment and Management

• Treatment for bilateral upper extremity weakness and numbness depends on the underlying cause, and may include disease-modifying therapies for MS 3, symptomatic treatment for nerve entrapment 4, and physical therapy.
• Gabapentin and pregabalin are commonly used to treat pain and other symptoms in MS patients 5, 6.
• Further research is needed to determine the effectiveness of these treatments and to develop new therapies for bilateral upper extremity weakness and numbness.