The Symptoms and Warning Signs of Diabetic Neuropathy

Neuropathy is a disorder or problem with the nerves. Diabetic neuropathy denotes nerve disorders due to diabetes.

Which nerves are affected in diabetes?

Before we answer this question, we need to have a little understanding of the nervous system.

The nervous system is made up of the central nervous system and the peripheral nervous system.

-The central nervous system consists of the brain and the spinal cord. This is a long, thin, tube like structure made of bundles of nerves.It extends from the base of the brain to the end of the spinal column.

– The peripheral nervous system consists of nerves branching out from the spinal cord. There are three different types of peripheral nerves: sensory, motor and autonomic.

• Sensory nerves: These nerves carry the sensations of touch, temperature, pain and pressure.Also other sensations like the position of joints and the sense of vibration from the skin, muscles or bone. These are relayed to the brain via the spinal cord so that a person can feel pain, correctly identify if an object is hot or cold, rough or smooth, and tell if a body part is in motion or not.
• Motor nerves: These nerves carry messages from the brain to the muscles via the spinal cord, and facilitate movement of the muscles, like walking, writing, catching a ball etc.
• Autonomic nerves: These nerves control involuntary and part-voluntary actions such as breathing, heartbeat, digestion, excretion of waste products, sweating etc.

What are the symptoms of diabetic neuropathy?

Symptoms depend on the nerve fibres affected. Sensory neuropathy (where the sensory nerve fibres are affected) or sensory-motor neuropathy (involving both the sensory and motor nerve fibres) are the predominant types of neuropathy seen in diabetic patients. They mainly affect the long nerves of the body. Hence feet and legs are affected first, then hands and arms are affected.This is also called distal symmetric neuropathy, as the affected nerves follow a glove-and-stocking distribution. Over the course of time, symptoms may move upward and affect the nerves of the front of the abdominal wall. They may also spread sideways over the trunk.

Sensory Neuropathy symptoms:

Sensory nerve fibres are commonly affected. Symptoms can be positive or negative. These symptoms are commonly worse at night.

Positive symptoms:

They arise spontaneously or in response to a stimulus. These include:

• Pain: Pain can either be continuous or intermittent. Pain that is predominantly experienced in the feet typically worsens at night and improves while walking. It can be experienced as a stabbing or shooting pain. Some patients also experience an aching type of feeling, or experience electric shock like sensations. Patients also frequently complain of burning sensations, and less frequently, a freezing sensation. Squeezing, constricting and cramping sensations have also been reported.
• Paraesthesia: These are abnormal sensations commonly known as pins-and-needles. They includes tingling, itching or pricking sensation, or the feeling of something crawling on the skin etc.
• Allodynia: This is a term used to denote pain from a stimulus that usually does not cause pain.Stroking or gentle touching is not usually painful, but a patient with neuropathy can experience intense pain when stroked.
• Hyperalgesia: A term used to indicate increased pain from a stimulus that usually causes mild pain. A person who stubs their toe on a piece of furniture might experience mild pain, but a patient with peripheral neuropathy will experience severe pain for the same injury.

Negative symptoms:

These represent a decreased response to a stimulus, including numbness and loss of sensation to a painful or thermal stimulus.

Motor neuropathy symptoms:

Motor nerve fibres are less commonly affected.

• Symptoms include muscle weakness leading to muscle wasting (muscle atrophy). If it involves the legs, the patient may experience difficulty in walking due to a decrease in muscle strength and a loss of reflex in the ankles. If the symptoms move upwards to the thighs, the patient may find it difficult to climb stairs. If the chest wall muscles are affected, the patient may experience difficulty in breathing.If the hand and arm muscles are affected, the patient may complain of being clumsy, for example, dropping objects. They may not be able to perform fine motor movements like writing with a pen or opening bottle caps.
• If the condition is severe, it may even result in paralysis of the affected area.
• Lack of co-ordination between various muscle groups leads to a loss of balance and frequent falls.
• Patients sometimes complain of muscle twitches and cramps.

Autonomic neuropathy symptoms:

Autonomic nerve fibres are affected. Symptoms include:

Symptoms associated with the heart and blood vessels: 

There is a problem with the body’s reflex to adjust the blood pressure and heart rate based on external stimulus. The patient may experience a sudden drop in blood pressure while standing or sitting. This leads to dizziness or faintness. The heart rate may persistently remain elevated (normally heart rate increases or decreases in response to normal body functions and physical activity).

One complication of autonomic neuropathy that is most important to understand is the silent heart attack. Normally a patient experiencing a heart attack complains of chest pain, but in autonomic neuropathy affecting the heart, the patient can experience a severe heart attack that may be painless. The patient may complain of other non-specific symptoms like vomiting or sweating. Because of this, adequate medical intervention is not provided at the appropriate time and the patient may die.

Symptoms associated with the digestive system:

The most common symptom is constipation. Some patients may have diarrhoea or alternating constipation. In some patients, stomach contents empty slowly into the small intestine. This leads to a feeling of fullness called gastroparesis. Severe gastroparesis leads to nausea and vomiting. If nerves in the food pipe are affected then the patient may have difficulty swallowing.

Symptoms associated with the urinary system:

The patient may not be able to completely empty the bladder, which can result in an overgrowth of bacteria leading to recurrent urinary tract infections. Nerve damage may also cause the patient to have urinary incontinence.This is because the patient is unable to sense that their bladder is full or they are unable to control the muscles that stop the urine from flowing.

Symptoms associated with the sex organs:

There is a decrease in sexual response in both men and women, although their sex drive may be intact. Males may not have erections (erectile dysfunction) or may not be able to ejaculate despite reaching sexual climax. Females may have problems with arousal, lubrication or climax.

Symptoms associated with sweat glands:

The sweat glands do not work normally. There may be reduced sweating resulting in dry skin and skin infections. On the other hand, the patient may complain of excessive sweating.

Symptoms associated with the respiratory system:

The patient may complain of difficulty breathing during exercise.

References:

• https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/nerve-damage-diabetic-neuropathies. Accessed June 11, 2017
• Peripheral neuropathy fact sheet. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/peripheralneuropathy/detail_peripheralneuropathy.htm. Accessed June 12, 2017
• Galer BS, Gianas A, Jensen MP. Painful diabetic neuropathy: epidemiology, pain description and quality of life, Diabetes Research and Clinical Practice, 2000 Feb;47(2):123-8.