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June 2012
Get A Hold On Your Nerves!
Dr Sudhir Kumar
Patients presenting with symptoms of nerve weakness are common in the outpatient sections of neurologists and general practioners making it a “common presenting symptom” for these practioners

Nerve weakness can occur in all age groups and affect both sexes. Nerve weakness adversely affects the quality of life and may lead to disability in some cases. There are a variety of causes for nerve weakness. It is important to identify the exact reason behind the weakness so that the correct remedial measures can be started on time.

Diseases And Ailments Linked To Nerve Weakness
Weakness can occur because of a disease of the nerves or due to a systemic (other system) illness. Some of the common neurological diseases that lead to nerve weakness are:
  • Brain stroke: Stroke can lead to sudden onset of weakness in one half (arm and leg) of the body. It occurs due to the blockage of blood supply to a part of the brain
  • Other brain diseases: Brain tumours, infections in the brain, brain haemorrhage (bleeding in the brain) can also lead to weakness of arms and legs.
  • Slipped disc (or disc prolapse): Prolapse of an inter-vertebral disc in the cervical (neck) region can lead to weakness of the arm on one side (due to compression of the cervical nerve). Similarly, prolapse of disc in the lumbar (lower back) region can lead to weakness of one leg (usually the foot). In addition, the patient may also have arm or leg pain.
  • Spinal cord compression: Compression of the spinal cord due to tuberculosis, fracture of spinal vertebrae (after fall or accident) or tumours can lead to weakness of arms and legs.
  • Nerve diseases: Nerves are affected in several conditions such as diabetes mellitus, leprosy, vasculitis (inflammation, leading to less blood flow to the nerves) and injury. These conditions lead to nerve weakness. In addition, the patients also have numbness and tingling of the affected areas.
Systemic Conditions Leading To Nerve Weakness
  • Anaemia: Patients with low haemoglobin complain of generalised weakness. 28 B+ve June I 2012 B Healthy
  • Heart failure: Patients with poor heart function also complain of weakness.
  • Chronic kidney disease: Patients with kidney diseases, especially those on long-term dialysis also suffer from weakness.
  • Infections: Most infections are associated with weakness. Some of them include viral fever, typhoid, malaria and tuberculosis.
  • Thyroid disorders: Patients with thyroid problems also complain of weakness, especially if the treatment is inadequate.
Weakness And Neuro-Degenerative Conditions
Weakness can be an initial presenting feature of a neuro-degenerative condition. However, it is heartening to note that it is true in only a small proportion of patients.

In children, the commonest disease in this category is muscular dystrophy. MD starts in the first decade of life and weakness continues to progress relentlessly leading to severe disability (and death) in the third decade of life.

In adults and older people, the commonest neuro-degenerative disease leading to weakness is amyotrophic lateral sclerosis (ALS, also called as motor neuron disease). ALS usually begins in the 5th or the 6th decade of life, leading to progressive weakness of arms and legs; and speech and swallowing muscles in some. ALS also has no cure and can lead to severe disability and respiratory muscle weakness.

As mentioned earlier, degenerative conditions, on the whole, are rare, and should only be considered in patients in whom weakness continues to worsen over long periods of time.

Weakness In Different Age Groups
Weakness can occur in all age groups; however, it occurs more commonly in older people. Though mild-general-weakness is a part of normal ageing and is common in the elderly, age alone does not predispose to severe nerve weakness. Older people have a higher prevalence of weakness, simply because the underlying causes leading to weakness are more common in them.

Weakness Due To Nutritional Deficiency
Nutritional deficiency is a common cause of weakness in all age groups and in both sexes. Some of the common nutritional deficiencies leading to weakness include deficiencies of the following:
  • Vitamin B12
  • Thiamine
  • Pyridoxine
  • Vitamin D
  • Iron
  • Protein deficiency
  • Vitamin B12 deficiency: Vitamin B12 is required for the normal growth and
    functioning of the nerves (in brain, spinal cord and nerves of extremities).
    It is especially required in the formation of myelin sheath (covering of the nerves). Therefore, Vitamin B12 deficiency leads to weakness of arms and legs. In addition, patients may also have memory problems, tingling and numbness of legs, and imbalance. Vitamin B12 deficiency can cause anaemia and contribute to the weakness. It is more common in pure vegetarians and older people.
  • Thiamine deficiency: It is common in chronic alcohol consumers. Sufferers have weakness, memory impairment and visual disturbances.
  • Iron deficiency: It is more common in women, especially those of the
    childbearing age. Iron deficiency occurs due to a combination of poor
    intake and blood loss (during child birth and heavy bleeding during periods).
    Iron deficiency anaemia is a common cause of weakness in women and
  • Protein deficiency: Protein deficiency is common in children, especially those in poorer sections of the society. It also occurs in people with chronic illnesses. Protein deficiency can lead to generalised weakness.

Be Warned On Body Building Medications!
Body building medications are sometimes prescribed to patients with weakness by non-qualified people. These mostly contain steroids and are very harmful. These steroids, also called anabolic steroids, are required in very specific situations and are not to be used routinely. These steroids may increase the muscle bulk, but are associated with a number of adverse effects such as weakness of bones (osteoporosis), increased infections, high BP, and high blood sugar.

Say Thumbs Up To Exercise In Recovery From Weakness
Exercise is extremely useful in speedy recovery from a neurological illness. It helps in regaining strength much faster. One should do the exercises under the guidance of good physiotherapists and should follow the schedule as suggested by them. Exercises should be continued for a considerable amount of time for desirable benefit. Exercise therapy is very safe and there are no adverse effects. Therefore, patients suffering from weakness need a combination of medications and exercise for complete recovery.

Risks Of Neglecting Nerve Weakness
Most cases of nerve weakness are potentially treatable if diagnosed early. However, if one ignores the initial symptom of weakness and allows the disease to progress, it can lead to irreversible damaget to nerves and the affected muscles. Any treatment started after the nerves and muscles have been damaged does not lead to complete recovery. Some treatments such as thrombolysis in brain stroke are timebound (It has to be given within 4.5 hours of symptom onset to ensure efficacy and safety.). It is important to see a neurologist or physician at the earliest, when one develops a weakness.
Disability due to nerve weakness:
  • Nerve weakness can lead to disability depending on the cause and severity of the illness and also depending on the nerves affected.
  • Involvement of the nerves in the leg leads to weakness of legs, hampering movement and walking. Sometimes, it leads to falls and injuries.
  • Arm weakness can severely interfere with normal activities of daily living - eating, bathing, brushing teeth, shaving, dressing and so on.
  • Disability can also interfere in job-related activities such as using computer/mouse/keyboard or writing.
  • Disability can be minimised by starting the treatment early and by proper exercises.
Treatment Of Nerve Weakness
Treatment depends on the underlying cause of nerve weakness. Treatment includes medications (oral tablets or injections) for treating the underlying cause and for nerveregeneration. Physiotherapy, occupational therapy and exercises are also very useful in recovery. Medications for nerve recovery are mainly vitamins and nutritionalsupplements, which include Vitamin B12, pyridoxine, thiamine, lipoic acid, etc. These are more useful in patients with nerve diseases due to diabetes mellitus, alcohol-relatednerve damage and those with nutritional deficiencies. These medications are safe and have no adverse effects.

Nerve Conduction Studies
Nerve conduction studies (which includes test for Nerve Conduction Velocity - NCV) are done to identify the nerves of arms and legs that are affected by a disease. It also helps in identifying the type of nerve damage and whether nerve covering (myelin sheath) is also damaged or not. NCV is done by a trained technician and is non-invasive. It involves stimulation of the nerves by a gentle electric current, recording of electrical nerve impulses on a computer and its analysis. In some cases, needle electromyography (EMG) is also done to identify the muscle involvement. This involves inserting the needles in the muscle and recording their activities.
Dr Sudhir Kumar is Senior Consultant Neurologist, Apollo Health City, Hyderabad.

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