Neuropathy is a condition that impacts the peripheral nervous system, which consists of the nerves extending outside the brain and spinal cord to the rest of the body. These nerves are responsible for transmitting signals that control movement, sensation, and automatic bodily functions. When these nerves are damaged, it can lead to symptoms such as pain, numbness, tingling, and weakness, often in the hands and feet. The interaction between viral infections and existing nerve conditions, especially COVID-19’s effects on individuals with neuropathy, is a significant area of study.
How COVID-19 Affects Existing Neuropathy
COVID-19 can worsen symptoms for individuals with pre-existing neuropathy. Studies indicate that a significant percentage of COVID-19 patients have reported symptoms of peripheral neuropathy following infection, with one study finding this in as many as 56% of patients post-infection. This exacerbation can manifest in various ways, impacting both sensory and motor nerves.
For instance, some people infected with SARS-CoV-2 experienced symptoms like pain, tingling, and numbness in their hands and feet during and after their illness. Research found that those who tested positive for COVID-19 were about three times more likely to report such symptoms compared to those with negative tests.
This includes both acute illness-mediated neuropathy, which can appear around the time of active infection, and small fiber neuropathy, often emerging later, typically within two to twelve weeks post-illness. Small fiber neuropathy specifically involves damage to the thinnest nerve fibers, which are responsible for pain and temperature sensation, and can result in burning pain. While some patients with pre-existing neuropathy might feel their condition worsening after a coronavirus infection, more direct evidence specifically showing COVID-19 worsening existing neuropathy (like diabetic neuropathy) is still being gathered.
Why Neuropathy Can Worsen After COVID-19
Several biological mechanisms are thought to contribute to why neuropathy might worsen after a COVID-19 infection. A primary factor is the body’s inflammatory response to the virus. The SARS-CoV-2 infection can trigger a robust immune reaction, leading to systemic inflammation and a “cytokine storm,” an overproduction of immune cells and their activating compounds. This heightened inflammatory state can cause damage to nerve tissues, contributing to neuropathic pain and other symptoms.
The virus may also affect blood vessels, leading to vascular issues that impair blood flow to nerves. Reduced blood supply can deprive nerve cells of essential oxygen and nutrients, leading to damage or dysfunction, a condition sometimes referred to as critical illness neuropathy. This ischemia can result in the physical breakdown of nerve cells and their ability to function properly.
Another contributing factor is the potential for autoimmune reactions. The immune system, in its effort to fight the virus, may mistakenly attack the body’s own nerve tissues. This “off-course” immune response can lead to conditions like Guillain-Barré syndrome, an autoimmune neuropathy, or other forms of autoimmune neuropathy. Such immune dysfunction appears to be a prominent cause of nerve damage observed in some patients with long COVID.
The stress of illness and recovery can induce metabolic changes that indirectly affect nerve health. For instance, COVID-19 has been linked to new-onset diabetes or the worsening of existing diabetes, which is a common cause of neuropathy. Glycemic abnormalities observed during acute illness can persist for months after recovery, potentially contributing to or exacerbating nerve damage.
Identifying Worsening Neuropathy and Seeking Care
Recognizing the signs that pre-existing neuropathy might be worsening after a COVID-19 infection is important for timely intervention. Common indicators include an increase in the intensity or frequency of existing symptoms such as numbness, tingling, or burning sensations. New symptoms might also appear, such as muscle weakness, painful muscle cramps, or involuntary muscle contractions. Some individuals may experience balance issues, changes in sensation to touch or temperature, or even changes in taste and smell.
Monitoring these symptoms is crucial, especially if they are persistent, rapidly worsening, or if new, severe pain or loss of function develops. If symptoms significantly impact daily activities, sleep, or quality of life, it is advisable to seek medical attention. A healthcare provider can evaluate the changes and determine if they are related to COVID-19 or another underlying cause.
A doctor may perform laboratory tests to rule out other common causes of neuropathy or conditions that could worsen symptoms, such as vitamin deficiencies or autoimmune diseases. An electromyography (EMG) test or nerve conduction study may also be ordered to assess nerve function and identify the type and extent of nerve damage. While no specific diagnosis exists for COVID-19-related neuropathy, current treatments can often manage symptoms regardless of the cause. Treatment focuses on controlling any underlying conditions and managing symptoms with medications that can alleviate nerve pain and discomfort.