Pathology of the Nervous System

The nervous system is affected by numerous drugs and diseases. These are very important in general practice and also in awareness against drug abuse.

Drugs acting on the nervous system

Several drugs are used to change the mood and/or emotional state of the user.  These drugs importantly either promote or decrease the action of a particular neurotransmitter – the chemical messengers that transmit impulses between neurons.

How do these drugs act on the nervous system?

These drugs act by 5 basic ways:

Examples of drugs that act on the nervous system

Diseases of the nervous system

There are numerous disorders of the nervous system. Some may affect the brain and spinal cord while some affect the peripheral nervous system.

Diseases of the Central Nervous System

These include meningitis and encephalitis. These may be bacterial or viral origin and may often be life threatening.

Polio is another infection of the central nervous system. It involves inflammation of the gray matter of the spinal cord. It may not have any symptoms or may cause paralysis of the lower limbs.

This is caused by derangements of normal connections in the brain. Episodes of convulsions are known as seizures.  There are "grand mal" and "petite mal" seizures.  In a grand mal seizure, the cerebrum becomes extremely excited, the individual may lose consciousness.

This is a disorder of childhood and occurs from birth in many. There is weakness of arms and legs. It is caused by lack of oxygen during birth which damages motor areas of cerebral cortex.

This is caused by rupture of a blood vessel within the brain leading to pressure over vital areas of the brain and this may cause paralysis and weakness of the limbs.

Other problems with the central nervous system include:

Diseases of the Peripheral Nervous System

Many conditions may also affect the peripheral nerves of the body leading to loss of sensation and paralysis.

Physical injury to the peripheral nerves is a common condition that affects their functioning. Often the peripheral nerves have the capacity to regenerate if they are injured. But this process of regeneration may take years of exercise and physiotherapy.

Damage to nerves may also be caused by swellings at places or channels where the median nerve passes through. This is called carpal tunnel syndrome.

Some conditions affect many of the terminal nerves. This is called peripheral neuropathy. Peripheral neuropathy may begin as a tingling numbness of the fingers and toes and extend along the limbs. It is commonly caused in diabetic individuals and those with certain genetic diseases of the nerves, vitamin deficiencies of vitamin B12 etc., infections such as herpes infection or leprosy, poisoning with Mercury, lead and other heavy metals, inflammatory conditions such as Guillain-Barré syndrome etc.

Neuropathy may also result from prolonged pressure to the nerve, leading to numbness and stiffness (pins and needles), sharp drops in temperature and prolonged action of local anesthetic drugs like lignocaine. An actual cause of peripheral neuropathy may also be elusive. This is called idiopathic neuropathy.

Further Reading

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.

Last updated Jun 5, 2019

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