Nerves (2) Sensory

Nerves (1) Summary  | Nerves (2) Sensory | Nerves (3) Autonomic

Somatic / Sensory Neuropathy

Diabetic neuropathy isn’t a singular condition, it’s the term used to describe a multitude of problems that arise as a result of nerve damage caused by the effects of diabetes.

People with diabetes may develop one or more types of neuropathy. Sometimes it might be a transient problem, which resolves itself over the course of a few months. Some forms of neuropathy involve damage to a single nerve and are called mononeuropathies (also classified as focal neuropathy). More commonly though, multiple nerves are affected, potentially causing any of a number of polyneuropathies.

Neuropathies are frequently referred to simply as being either somatic (sensorimotor/’sensory’) or autonomic; this page looks at somatic neuropathies. Part 3 looks at autonomic neuropathies.

What’s covered on this page

Treatments for neuropathic pain
Rapidly reversible neuropathy
Acute sensory neuropathy
Chronic sensorimotor neuropathy
Focal and multifocal neuropathies
Chronic inflammatory demyelinating polyneuropathy (CIDP)




Sensory nerves detect pain or feelings, and send messages to the “central nervous system” (CNS). The CNS – which is essentially the brain – processes the messages and sends responses through motor nerves.

Damage to small sensory nerve fibres (known as C-fibres) affects sensation of pain, temperature, light touch and pin-pricks. Damage to large sensory nerve fibres reduces sensation of vibration, affects muscle strength, and reduces position sense (which, in turn, affects balance and orientation).

Damage to motor nerve fibres affects muscle function and effectively reduces the ability to move or control the movement of various parts of the body.


Treatments for neuropathic pain

Paracetamol or a non-steroidal anti-inflammatory drug such as ibuprofen may relieve mild to moderate pain.

The tricyclic antidepressants amitriptyline (Amitrip) and nortriptyline (Norpress) are frequently the drugs of choice for painful diabetic neuropathy.

Antiepileptic drugs are also useful in treating neuropathic pain. Gabapentin (Neurontin) is used for the treatment of neuropathic pain and is an effective alternative to a tricyclic antidepressant. Carbamazepine (Tegretol; Teril) or phenytoin (Dilantin) may be useful for shooting or stabbing pain, but adverse effects are common.

Capsaicin cream 0.075% (Zostrix HP) can be helpful, but it does produce an intense burning sensation during the initial treatment period. Lignocain cream (Emla – a local anaesthetic cream) may also be useful in some cases.

Neuropathic pain may respond partially to some opioid analgesics, such as methadone (Biodone; Pallidone; Methatabs) oxycodone (OxyContin; OxyNorm) and tramadol (Tramal; Zytram), and these may have a role if other treatments have been unsuccessful.



Rapidly reversible neuropathy

This type of neuropathy is sometimes referred to as hyperglycaemic neuropathy.

When the blood glucose level is high, temporary abnormalities in nerve function can occur. This tends to happen more commonly in people who have only recently been diagnosed with diabetes, and sometimes in people who suffer from transient periods of poorly controlled diabetes or high blood glucose levels. It may also be a problem for people with impaired glucose tolerance (IGT) or impaired fasting glucose (IFG) – i.e. those people with pre-diabetes – and intuitively it seems reasonable to think that this type of neuropathy may also occur in people who clinically have diabetes, but who have not yet been diagnosed.

This type of neuropathy is related to temporary changes in nerve function, which revert to normal when blood glucose levels are restored to normal. It is therefore said to be an “acute” problem, and it is thought that the changes are more likely related to abnormalities in function caused by high glucose levels, as opposed to permanent changes in structure caused by high glucose levels.

The possibility that a person that suffers from rapidly reversible neuropathy is at a higher risk of suffering from other chronic forms of neuropathy is yet to be confirmed.


Acute sensory neuropathy

As the name suggests, acute sensory neuropathy is characterised by it’s sudden or “acute” onset of sensory symptoms – usually pain – with few or no clinical signs (such as might be diagnosed on a neurologic examination of the legs, for example). Symptoms are frequently much worse at night.

This painful neuropathy is often related to periods of poor diabetes control, ketoacidosis, sudden or severe weight loss, and eating disorders. However, occasionally it may occur after a sudden improvement in control.

Usually, graually improvement of symptoms is seen over time or with improvement in blood glucose control (similar to rapidly reversible neuropathy, above). Complete recovery from severe sympoms is generally achieved within a year.

This type of neuropathy is an acute form of “distal symmetric polyneuropathy” (DPN). Sometimes it is referred to as “acute painful neuropathy”.

Chronic sensorimotor neuropathy

This is the most common form of diabetic neuropathy. It tends to develop slowly and subtly, and may be present clinically in patients before they are aware of any sympoms. However, 10 – 20 % of paients may experience troublesome sensory symptoms that are sufficient to require treatment.

Technical/medical terms used in relation to
“chronic sensorimotor neuropathy”

This type of neuropathy is sometimes referred to as “chronic sensorimotor distal symmetric polyneuropathy”.

That’s a complicated term; sometimes it is shortened in various ways, such as to “distal polyneuropathy”, “chronic sensorimotor DPN”, “chronic DPN”, or simply “DPN”.

Sometimes this type of neuropathy is more generally referred to as “peripheral neuropathy”, but in fact this term embraces all of the neuropathies described on these pages.

Problems such as foot ulceration and Charcot foot are associated with longer term neuropathy of this sort (see section “Legs and Feet“).

In the most common forms of polyneuropathy, nerve fibers (the individual cells that make up the nerve) most distant from the brain and the spinal cord are affected first. Pain or numbness and other symptoms tend to appear symmetrically – in both feet, for example – followed by a gradual progression “inwards” towards the spinal column – up both legs, in this example. Toes and the soles of the feet thus tend to be affected first. Depending on the individual, the fingers, hands, and arms may be affected, but this tends to happen less often and is less severe.

Symptoms may sometimes progress right up to the central part of the body. If sensory loss has reached the mid-thighs and upper forearms, it may also be affecting the lower abdomen.

Weakness in foot muscles may result in a reduced ability to move the toes or foot upwards. As this muscle weakness progresses it becomes difficult to walk on the heel. Additionally, damage to the sensory system that enables us to maintain our balance may result in unsteadiness and a “wobbly” kind of walk (this is termed an “unsteadiness of gait”).

A clinical examination of the lower limb in people with chronic DPN may reveal sensory loss in relation to:

  • vibration
  • pressure
  • pain
  • temperature

Reduced or absent ankle reflexes may also be demonstrated.

These tests should be performed on a regular basis at least once a year, as part of the Annual Review

Sensorimotor neuropathy is often, but not always, accompanied by autonomic neuropathy.


Focal and multifocal neuropathies (Mononeuropathy)

Mononeuropathies affect a single nerve, or a specific group of nerves.

Focal neuropathies involve a single focal lesion, affecting a single nerve fibre.

Multifocal neuropathy (also called “mononeuropathy multiplex” or “mononeuritis multiplex”) refers to the involvement of multiple lesions on separate nerves. The term is used to describe a group of symptoms, as opposed to being a distinct disease entity. The underlying disorder affects isolated nerves in multiple, random areas. As the disorder worsens, the damage may become more diffuse and less focused on particular areas; at this later stage it may present as an apparent polyneuropathy.

Some specific problems are due to entrapment, or compression (e.g. carpel tunnel syndrome – see below), other mononeuropathies are the result of a reduced blood flow or inflammation of the blood vessel supplying the nerve (“vasculitis”).

Focal Limb Neuropathy (Limb Mononeuropathy)

The most common mononeuropathies are caused by the entrapment or compression of nerves. Of these, Capel Tunnel Syndrome is most common. It is the result of compression of the median nerve at the wrist. Painful pins-and-needles in the fingers may progress to a deep ache up the forearm, towards the elbow. Interestingly, Carpal tunnel syndrome is apparently more common in patients with Type 1 diabetes (11% with symptoms in Type 1’s vs 6% in Type 2’s (1)).

Ulnar neuropathy at the elbow is the second most common mononeuropathy. It is an entrapment syndrome, caused by the compression of the ulnar nerve at, or near, the elbow.

Typically, these neuropathies are slowly developing, and have variable amounts of pain and/or weakness.

Other nerves less frequently affected include the radial nerve (wrist drop), peroneal nerve (foot drop), femoral nerve (quadriceps weakness), and lateral femoral cutaneous nerve in the thigh (“meralgia paresthetica”). Dysfunction of these nerves may be sudden and painful.

Proximal Motor Neuropathy (Amyotrophy)

This type of neuropathy, frequently referred to as “diabetic amyotrophy” is more common in people with Type 2 diabetes and, typically, patients are aged 50 – 60 years. Severe pain is accompanied by muscle weakness and muscle wasting in one or both thighs. Weght loss is common at the onset.

The main aim for therapy is to control the pain. Immunotherapy may be of benefit, but conclusive evidence is awaited. The prognosis (outlook) for this type of neuropathy is variable. It runs its own course over months or years, and recovery may be partial or complete.

Focal Cranial Neuropathies

Cranial mononeuropathies are rare, but deserve a mention nevertheless. They tend to occur in older people who have had diabetes for a long time. Cranial nerves originate from the brain or cranial cavity and stimulate muscles that control eye and facial movement. Cranial neuropathies may cause misalignment of the eyes either vertically, or horizontally, depending on which nerve is affected. Droopy eyelids may also occur.

Facial palsies (a specific kind of paralysis of certain facial muscles) may also result from cranial mononeuropathies. Other neurological facial problems that may occur more frequently in people with diabetes include trigeminal neuralgia (shooting jaw pain). Degrees of hearing loss have also been reported.

As with all of the neuropathies, blood glucose control and blood pressure management, and reduction of other risk factors (smoking, alcohol) are the mainstay of treatment; in many instances focal cranial neuropathies resolve themselves over time.

Thoracolumbar Radiculoneuropathy (Truncal Mononeuropathy)

This type of neuropathy affects middle aged to elderly people with diabetes and seems to be more common in men.

Damage to the roots of the nerves, which lie along the spinal column can cause radiculoneuropathy (sometimes shortened to radiculopathy), which can result in aching or burning thigh pain, and/or girdle-like pain around the abdomen or lower chest. The latter has also been referred to as “truncal mononeuropathy”. Sometimes the burning pain is superceded with sharp stabbing pains. Symptoms are often worse at night. The onset of symptoms may be accompanied by significant weight loss.

Generally, this type of neuropathy resolves itself over 4 – 6 months.

Chronic inflammatory demyelinating polyneuropathy (CIDP)

Chronic inflammatory demyelinating polyneuropathy (CIDP) is characterised by progressive weakness and impaired sensory function in the legs and arms. It is caused by damage to the myelin sheath of the peripheral nerves – this is the fatty covering that wraps around, and protects the nerve fibers.

Although outwardly similar to Proximal Motor Neuropathy / Amyotrophy (see above), this type of neuropathy is quite distinctly different, and it can be treated successfully with corticosteroids, sometimes in combination with immunosuppressant drugs.

Physiotherapy can help to maintain some muscle strength, function and mobility, and minimise the ‘wasting’ of muscles. It can also help to preserve tendons and joints.

The disorder is sometimes referred to as “chronic relapsing polyneuropathy”.