How many types of diabetic neuropathy should you be aware of?

Diabetic neuropathy is a term coined for any and all kinds of nerve disorders that are seen to be an important complication of chronically uncontrolled diabetes of long standing. Diabetes as such affects the patient’s quality of life adversely and diabetes with neuropathy is only further debilitating.

The various types of diabetic neuropathy may be grouped on various bases as follows:

On the basis of the type of nerves affected:

Sensory - these nerves carry sensory information and perception from the peripheral parts of the body like the skin, to the central nervous system, the brain and the spinal cord. They include senses like that of temperature, touch, pain etc. It is a painful kind of diabetic neuropathy.

Sensory nerve damage symptoms thus include:

●     a “pins and needle sensation” i.e. a sharp tingling, prickling or burning sensation of the skin

●     numbness and reduced/ lost sensitivity to touch and temperature

●     sharp pain in affected areas

●     an enhanced sensitivity to touch

●     a loss of coordination and balance

Due to the lack of a continuously functioning sensory feedback mechanism, these patients are at a higher risk of developing calluses, injuries, ulcers, and infections from them.

Motor - these nerves carry the motor/ mechanical activity messages from the brain and the central nervous system to the body’s periphery, the musculature and the skeleton. Thus, motor nerve damage leads to

●     muscle weakness

●     loss of reflexes

●     deformities

●     contractures.

It is rarely found to be an isolated nerve damage as a result of diabetic neuropathy, and usually occurs as a sensorimotor polyneuropathy.

 Autonomic - these nerves control the autonomic functioning and the involuntary actions of the viscera of the body, such as the heart, stomach, intestines, lungs, and the urinary bladder. Autonomic nerve damage can ultimately lead to symptomatic manifestations like:

●     diabetic diarrhea,

●     bloated stomach,

●     hypoglycemic unawareness,

●     orthostatic hypotension and fainting

●     impotence in males,

●     bladder and voiding disorders,

often leading to further complications.

Cranial- the cranial nerves supply the face and the cranium. The most commonly affected cranial nerve in diabetes is the 3rd, the oculomotor nerve. It controls all the muscles responsible for the movement of the eyeball, except the lateral rectus and superior oblique muscles. It also has a role in opening the eyelids as well as in constricting the pupil.

The symptoms include:

●     frontal and periorbital pains

●     diplopia (double vision)

On the basis of extent of nerves affected:

1.    Mononeuropathy- a single type of nerve is affected in this.

2.    Polyneuropathy- several nerves or nerve groups are affected in this type.

On the basis of pattern of nerves affected:

1.    Symmetric- the nerves of only one of the two sides of the body are affected in this.

2.    Asymmetric- the nerves of both the sides of the body are affected in this.

On the basis of the region of the body affected:

Peripheral or Distal Neuropathy - Any damage to nerves outside of the brain and spinal cord can be generalised under peripheral neuropathy. In Diabetic neuropathy, the peripheral/distal neuropathy most commonly affects the upper and the lower limbs, usually symmetrically, but may be asymmetrical in some. This distribution is often referred to as the ‘glove-stocking distribution’. It is a sensorimotor type of nerve damage and thus has the same symptoms, and is the most frequently diagnosed type of neuropathy in diabetes.

Proximal Neuropathy- pain and numbness (usually unilateral) in the legs, thighs, hips, or buttocks are a result of this type of neuropathy, often also leading to a severe weakness of the leg muscles, typically causing a loss of ability to stand up from a sitting position without help. It is also known as femoral neuropathy. The weakness and pain usually call for either medication or physical therapy.  

Focal Neuropathy - the neuropathy affecting a specific nerve or nerve group only. It has an abrupt onset, mostly affects the head, torso, and legs, and causes muscular weakness along with pain. Its symptoms include:

●     diplopia (double vision)

●     pain in the eyes

●     Bell's palsy (paralysis of one side of the face)

●     pain in a specific region

●     chest / abdominal pain

It has a good prognosis even without treatment, and does not cause any long-term damages.