Peripheral Neuropathy

Peripheral neuropathy refers to a group of symptoms caused by damage or injury to the peripheral nerves, leading to dysfunction. The peripheral nerves are located outside the central nervous system, meaning outside the brain and spinal cord, and they transmit information between the central nervous system and the rest of the body. Peripheral nerves are classified based on their function:

• Sensory nerves: Transmit information from the skin and senses, such as temperature, pain, sight, or touch.
• Motor nerves: Responsible for muscle movement.
• Autonomic nerves: Control involuntary bodily functions such as heart rate, blood pressure, sweating, digestion, or urination.

More than 100 types of peripheral neuropathy have been classified, which are categorized into three main groups depending on the number of affected peripheral nerves:

• Mononeuropathies: Dysfunction of a single nerve.
• Multiple mononeuropathies or multifocal neuropathies: Two or more nerves in different areas of the body are simultaneously affected.
• Polyneuropathies: Affect multiple nerves at the same time, usually in a bilateral, symmetrical, and diffuse manner.

Additionally, based on their manifestation, they are divided into:

• Acute peripheral neuropathy: Symptoms appear suddenly, progress rapidly, and improve slowly as the affected nerves heal.
• Chronic peripheral neuropathy: Symptoms develop subtly and progress slowly. Periods of remission may alternate with relapses, or the condition may reach a prolonged stagnation phase. In many cases, symptoms worsen over time.

Symptoms

The symptoms of peripheral neuropathy vary depending on the type of nerves affected:

Motor Peripheral Neuropathy Symptoms:

• Muscle weakness.
• Cramps.
• Visible (fasciculations), uncontrolled, and painful muscle contractions.
• Muscle atrophy: Reduction in muscle size.
• Decreased reflexes.
• Difficulty moving.

Sensory Peripheral Neuropathy Symptoms:

• Reduced tactile sensations, especially in the hands and feet, causing a feeling of wearing gloves or socks.
• Tingling or numbness in the hands and feet, extending to the legs and arms.
• Coordination and balance problems.
• Neuropathic pain: Stabbing, sharp, and throbbing pain that often worsens at night.
• Extreme sensitivity to touch: Pain from non-painful stimuli, such as the touch of bed sheets.
• Sometimes, loss of sensation.

Autonomic Peripheral Neuropathy Symptoms:

• Sweating disorders: Excessive sweating or inability to sweat, leading to heat intolerance.
• Loss of bladder control.
• Low blood pressure due to dysfunction in the muscles that expand or contract blood vessels to regulate pressure.
• Sometimes, irregular heart rate.
• Gastrointestinal disorders: Diarrhea, constipation, or incontinence.
• Difficulty swallowing.

Causes

Nerve damage occurs either due to degeneration of axons (the neuron’s stem) or due to loss of myelin, the lipoprotein sheath covering the axon. This damage can have various causes, dividing neuropathies into three groups:

• Hereditary neuropathies: Caused by mutations in genes forming myelin or axons, such as PMP22, MFN2, MPZ, and EGR2. Examples include Charcot-Marie-Tooth disease, porphyria, and Fabry disease.
• Acquired neuropathies: Result from various conditions, disorders, or situations that cause nerve damage.
• Diabetes: The most common cause of peripheral neuropathy.
• Other metabolic and endocrine disorders, such as hypothyroidism, excessive growth hormone production, kidney disease, or liver disease.
• Vasculitis: A group of diseases causing inflammation of blood vessels.
• Autoimmune diseases, such as lupus, rheumatoid arthritis, Sjögren’s syndrome, paraneoplastic syndrome, or Guillain-Barré syndrome.
• Benign or malignant tumors.
• Viral or bacterial infections, including herpes simplex, varicella-zoster, West Nile virus, HIV, Lyme disease, diphtheria, or leprosy.
• Bone marrow disorders, such as monoclonal gammopathy, lymphoma, or amyloidosis.
• Traumatic or pressure injuries, such as blows, falls, surgeries, herniated discs, repetitive movements, or extreme postures.
• Certain medications, including chemotherapy drugs, antiretrovirals, anticonvulsants, or antihypertensives.
• Chronic alcoholism.
• Vitamin deficiencies: B vitamins and vitamin E are essential for nerve health.
• Exposure to toxins, such as insecticides, solvents, or heavy metals.
• Idiopathic neuropathies: Cases where no cause can be identified.

Risk Factors

The main risk factors for developing peripheral neuropathy include:

• Family history.
• Presence of diseases and disorders associated with neuropathy.
• Traffic accidents or sports injuries.
• Activities involving repetitive movements or unnatural postures, such as working with vibrating tools.
• Alcohol abuse.
• Exposure to toxins.
• Use of medications linked to neuropathy.

Complications

The numbness caused by neuropathy can be dangerous, as individuals may not feel pain and may suffer cuts, burns, or other injuries without realizing it. This can lead to severe infections, potentially resulting in gangrene or life-threatening conditions. Additionally, lack of pain sensation can cause people to overlook severe symptoms, such as chest pain signaling a heart attack, delaying crucial medical intervention.

Coordination and balance issues increase the risk of falls, which can be hazardous depending on the circumstances. Other common neuropathy symptoms, such as muscle weakness, cramps, fasciculations, or neuropathic pain, can severely impact quality of life, preventing normal daily activities.

Chronic sensory neuropathy can also cause joint and bone damage. Autonomic neuropathy, on the other hand, may lead to incontinence, sexual dysfunction, or even malnutrition if the nerves controlling chewing, digestion, or swallowing are affected.

Prevention

The most effective way to prevent peripheral neuropathy is to follow the appropriate treatment for underlying conditions. Additionally, avoiding alcohol consumption, maintaining a vitamin-rich diet, and adhering to safety measures to prevent accidents or injuries while driving or engaging in sports are recommended.

What Doctor Treats Peripheral Neuropathy?

Neuropathy is evaluated and treated by specialists in neurology and neurosurgery.