Nervous System and Mental Function Injuries and Disorders

Nervous System and Mental Function

The nervous system is composed of the brain and spinal cord, together known as the central nervous system, and a vast array of peripheral nerves that transmit information to and from these central structures. The nervous system may be damaged by infection, injury, vascular problems, inflammation, and degeneration. However, the causes of many general nervous system disorders are not fully understood.

The first article deals with pain, which is a common symptom of many disorders. A description of the pain often helps in the diagnosis of a disorder. Effective painkillers and treatments such as transcutaneous electrical nerve stimulation (TENS) mean that prolonged, severe pain can be effectively treated and/or controlled.

The different types of headache are discussed next. Tension headaches cause discomfort and pain to millions of people every year, often due to stress or tension. Migraine is also relatively common, while cluster headaches are a severe but less common type of headache that occur in a characteristic pattern. A headache can be a sign of an underlying disorder, and persistent or severe headaches associated with other symptoms, such as vomiting, should be assessed by a doctor without delay.

The final article in this section discusses chronic fatigue syndrome, a complex and debilitating condition.

Headaches and migraine in children are covered elsewhere (see Infancy and childhood).

Key anatomy

For more information on the structure and function of the brain and spinal cord.


The brain and spinal cord process all incoming information from different sense organs throughout the body and coordinate appropriate responses. Both the brain and the spinal cord are connected to other parts of the body by the peripheral nerves. The brain and spinal cord are protected by overlying membranes as well as by the skull and the flexible, bony vertebral column.

The first articles in this section cover head injuries and different states of unconsciousness, such as coma. Spinal injuries, often caused by whiplash in road accidents, are described next.

Disorders associated with abnormal brain function, such as epilepsy and narcolepsy, which causes an irresistible tendency to sleep are then discussed. The next articles focus on infectious disorders affecting the brain, such as meningitis, in which the membranes surrounding the brain and spinal cord are inflamed, and viral encephalitis, in which the brain becomes inflamed. Cancerous and noncancerous brain tumours are then described.

Different types of stroke and brain haemorrhages, all of which may affect speech, mobility, or mental ability, are discussed next. The final articles in this section deal with degenerative disorders, such as types of dementia and motor neuron disease.

General disorders that affect the brain, such as headache, are discussed elsewhere (see General nervous system disorders).

Key anatomy

For more information on the structure and function of the peripheral nervous system.

Head Injuries


Persistent Vegetative State

Brain Death

Spinal Injuries




Viral Encephalitis

Brain Abscess

Brain Tumours

Transient Ischaemic Attacks


Subarachnoid Haemorrhage

Subdural Haemorrhage


Alzheimer’s Disease

Multi-infarct Dementia

Wernicke–Korsakoff Syndrome

Huntington’s Disease

Parkinson’s Disease and Parkinsonism

Creutzfeldt–Jakob Disease

Motor Neuron Disease

Multiple Sclerosis

The peripheral nervous system is composed of nerves that branch from the brain and spinal cord and then divide repeatedly to supply every part of the body. The nerves transmit information necessary for sensation, muscle stimulation, and the regulation of unconscious functions. Disorders of these nerves may be painful, cause loss of sensation, or lead to paralysis.

This section starts with an overview of peripheral neuropathies, in which one or more peripheral nerves are damaged. Peripheral neuropathies are relatively common and have many causes, including injuries, infection, nutritional deficiencies, and disorders such as diabetes mellitus. Diabetic neuropathy, the most common cause of peripheral nerve damage, is covered next. This is followed by an article on nutritional neuropathies, in which deficiency of essential nutrients in the diet, especially the vitamin B complex, causes the nerve damage.

The next articles cover disorders such as sciatica, carpal tunnel syndrome, and facial palsy, all of which may be caused by compression of a nerve. Rarer disorders that affect peripheral nerves are covered next. Such disorders include myasthenia gravis, in which the immune system affects the body’s ability to transmit impulses from the nerves to muscles, and Guillain–Barré syndrome, which is the result of an abnormal response of the immune system after an infection. The final article covers nervous tics, which are often caused by stress.

Key anatomy

For more information on the structure and function of the peripheral nervous system.

Peripheral Neuropathies

Diabetic Neuropathy

Nutritional Neuropathies

Trigeminal Neuralgia


Carpal Tunnel Syndrome

Facial Palsy

Peripheral Nerve Injuries

Myasthenia Gravis

Guillain–Barré Syndrome

Nervous Tics

Test: Nerve and Muscle Electrical Tests

Few people hesitate to seek treatment for a physical illness, but many find it hard to accept that they may have a mental health problem. However, disorders such as depression, anxiety, and problems with alcohol and other drugs are common, increasingly understood, and treatable. No one needs to be embarrassed about a mental illness or feel that he or she must deal with it alone.

This section begins with anxiety disorders, which are among the most common mental health problems in the UK. Feeling worried is a natural reaction to problems and stress. However, persistent anxiety, often with no obvious cause, needs treatment to prevent it from becoming a long-term problem. Phobias, excessive fears of anything from spiders to confined spaces, can dominate many areas of a person’s life. Other anxiety-related illnesses include post-traumatic stress disorder, a response to events such as serious accidents and natural disasters, and obsessive–compulsive disorder, in which uncontrollable thoughts – obsessions – cause anxiety, leading to urges to perform certain acts – compulsions – to relieve the anxiety.

Insomnia, a symptom of many mental illnesses, particularly anxiety and depression, is covered next. Depression, a very common disorder that affects an estimated 1 in 3 people at some time in their lives, is described in the article that follows. It requires prompt treatment to relieve symptoms and prevent persistent feeling of despair, and possibly even suicide. The next article cover bipolar affective disorder, in which mood alternates between extreme highs and lows.

The common factor in the next group of disorders, which includes Munchausen’s syndrome, somatization, and hypochondriasis, is the relationship between the mind and physical symptoms. Schizophrenia, a severe mental illness that may cause disturbed emotions and disordered thinking, delusional disorders, personality disorders, and Tourette’s syndrome are also discussed.

The final articles deal with the eating disorders anorexia nervosa and bulimia, alcohol and drug dependence, and compulsive gambling.

Anxiety Disorders


Post-traumatic Stress Disorder

Treatment: EMDR

Obsessive–compulsive Disorder



Attempted Suicide and Suicide

Bipolar Affective Disorder

Mental Problems due to Physical Illness

Munchausen’s Syndrome




Delusional Disorders

Personality Disorders

Tourette’s Syndrome

Anorexia Nervosa


Drug Dependence

Alcohol Dependence

Compulsive Gambling

Test: Psychological Assessment

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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