Diabetic Neuropathy

Original Editor - Wendy Walker

Top Contributors - Sheik Abdul Khadir, Lucinda hampton, Wendy Walker, Kim Jackson, Chloe Waller, Garima Gedamkar, Vidya Acharya, Uchechukwu Chukwuemeka, Amanda Ager, WikiSysop, Ibrahim Khalil and Karen Wilson  

Introduction

Diabetic neuropathy is dysfunction and damage in the peripheral nerves in people with diabetes. Neuropathies are characterized by a progressive loss of nerve fibre function. Diabetic neuropathy is a common complication of Diabetes Mellitus (DM), estimated to affect up to 51% of patients with both type 1 and type 2 DM. The clinical presentation of diabetic neuropathy varies, from asymptomatic to severe neuropathic pain and numbness. Diabetic neuropathy is associated with increased risk of foot ulcers, lower limb amputation and mortality.

Clinically Relevant Anatomy

The peripheral nervous system refers to the components of the nervous system outside of the brain and spinal cord. The nerve roots exit the spinal cord and then branch out into smaller peripheral nerves. The peripheral nerves consist of motor and sensory fibers.

In diabetic neuropathy, they’re is degeneration in the type, severity, and distribution of these receptors, nerve fibers, or neurons, with the degeneration beginning distally and symmetrically, and spreading proximally.

Mechanism of Injury / Pathological Process

The pathological process of diabetic neuropathy is not completely understood, and is likely multifactoral. Research suggests neuronal inflammation, oxidative stress, mitochondrial dysfunction and cell death is caused by hyperglycaemia, dyslipidaemia and microvascular disease.

Risk Factors

• Poor glycemic control.
• High blood pressure
• Smoking.
• Advance age.
• Advanced duration of Diabetes disease.
• Heavy alcohol intake.
• Tall stature
  

Clinical Presentation

More than half of the cases are distal symmetric polyneuropathy. Asymmetrical or focal syndromes, such as carpal tunnel syndrome (14-30%), radiculopathies/plexopathies and cranial neuropathies, account for the rest.

Motor Symptoms

Motor problems may include distal, proximal, or more focal weakness.

1. In the upper limbs- distal motor symptoms often include impaired fine hand coordination.
2. In the lower limbs - Mild foot drop or frequent tripping may be early symptoms of lower limb weakness. Symptoms of proximal limb weakness include difficulty climbing up and downstairs, difficulty getting up from a seated or supine position, falls due to the knees giving way, and difficulty raising the arms above the shoulders.

Sensory Symptoms

A slow, insidious onset sensory neuropathy typically shows a stocking-and-glove distribution in the distal extremities.

Sensory symptoms may be negative or positive, diffuse, or focal.

• Negative sensory symptoms include feelings of numbness or deadness, which patients may describe as being akin to wearing gloves or socks. Loss of balance, especially with the eyes closed, and painless injuries due to loss of sensation are common.
• Positive symptoms may be described as burning, prickling pain, tingling, electric shock–like feelings, aching, tightness, or hypersensitivity to touch.

Diagnostic Procedures

Testing includes assessment of gross light touch and pinprick sensation. The first clinical sign that usually develops in diabetic symmetrical sensorimotor polyneuropathy is the reduction of vibratory and pinprick sensation over the toes. As the disease progresses, the level of decreased sensation may move upward into the legs and then from the hands into the arms, a pattern often referred to as "stocking and glove" sensory loss. Very severely affected patients may loose sensation in a "shield" distribution on the chest.

Vibratory sense in the feet is tested with a 128-Hz tuning fork placed at the base of the great toenail.
Deep tendon reflexes are commonly hypoactive or absent.

The latest recommendations continue to advocate a multimodal approach to assessing diabetic neuropathy. This should include symptoms and signs, quantitative sensory testing, and electrophysiology.

Classification

Diabetic neuropathy can be classified into 4 subgroups:

• Proximal neuropathy/ diabetic amyotrophy.

• Peripheral neuropathy / diabetic nerve pain / distal polyneuropathy.
• Autonomic neuropathy.
• Focal neuropathy / mononeuropathy.

Staging

A common staging scale of diabetic neuropathy is as follows: 

• N0 - No neuropathy.
• N1a - Signs but no symptoms of neuropathy.
• N2a - Symptomatic mild diabetic polyneuropathy; sensory, motor, or autonomic symptoms; patient able to heel walk.
• N2b - Severe symptomatic diabetic polyneuropathy, and patient unable to heel walk.
• N3 - Disabling diabetic polyneuropathy.

Medical Management / Interventions

Medical management starts with 0ptimized glycemic control (mainly for type 1 DM) and lifestyle interventions. Lifestyle intervention includes physical exercise and weight loss.

Tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors (e.g. duloxetine) and anticonvulsants (e.g. pregabalin and gabapentin) are commonly prescribed treatments for neuropathic pain. At present, there are no universally accepted disease modifying medicines, but this is currently being researched and developed.

Moreover, multidisciplinary team management is required for the prevention and management of diabetic foot complications.

Physiotherapy Management and Exercise

Research has shown that strength training can moderately improve muscle function in people with peripheral neuropathy (PN). Regular exercise can also help reduce neuropathic pain and help control blood sugar levels. Diabetic clients must tightly monitor their blood sugar levels during exercise to prevent major fluctuations. This may involve educating clients and monitoring blood sugars, ideally through a multi-disciplined approach in rehabilitation.

Specific exercise programs should include

• Flexibility (progressive stretching and self stretches)
• Muscle strengthening ( using a variety of modes as appropriate eg isometric, graded weight progression, open and close chain)
• Aerobic activity ( aiming for 30 minutes 4 times a week)
• Balance ( for falls prevention and stability)
• Gait (can improve gait pattern or walking in patients with diabetic neuropathy) Evidence shows that resistant strengthening exercises lower blood glucose level

The youtube below shows some good exercises that a physiotherapist can employ to help manage the symptoms of diabetic neuropathy.

A 2014 review found that the biggest consequence of diabetic neuropathy was a increase in risk of falls. Therefore balance and falls prevention programs and or training, in the senior diabetic clientele in particular, by a physiotherapy is very beneficial.

Physiotherapy may also involve splinting for mononeuropathies eg. carpal tunnel or for muscle weakness eg Ankle foot orthoses.

As a consequence of diabetic neuropathy physiotherapist are involved in

The Diabetic Foot.

The Diabetic Amputee.

Physiotherapeutic Management of Pain in Diabetic Neuropathy

see also Nerve Injury Rehabilitation Physiotherapy

Evidence has been provided for:

1. Transcutaneous Nerve Stimulation (TENS)
2. Static magnetic field therapy
3. Low-intensity laser therapy
4. Monochromatic infrared light

Differential Diagnosis

Other possible causes of neuropathy include:

• Autoimmune disorders (e.g.  Guillain-Barré syndrome, systemic lupus erythematosus, and rheumatoid arthritis)
• Inherited disorders (e.g. Charcot-Marie-Tooth Disease)
• Infections (e.g. chicken pox, HIV, hepatitis c and Lyme disease)
• Alcoholism
• Vitamin deficiency (e.g. vitamins B1, B6, B12, vitamin E and niacin)
• Trauma

• Toxins (e.g. heavy metals and industrial chemicals)
• Medications (e.g. some antibiotics or chemotherapy)
• Hypothyroidism
• Vascular disorders.