Overview of neuropathies

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Overview of neuropathy

A neuropathy is a general term that refers to a disease of condition resulting in nerve disorders. The body is made up of nerves which make up the nervous system and these are used for communication purposes between the internal and external environment. The nervous system also communicates with the brain and spinal cord to ensure that there is a continuous feedback system.

Nerves are also very critical in the coordination of voluntary movement and thus the reason as to why nerve disorders should be addressed as soon as possible. It is also the nerves that are used in the coordination of the involuntary action such as blood pressure regulation, body temperature regulation and important body processes such as breathing and the heart rate.

Any of the nerve disorders at any point in the body is termed as a neuropathy and is classified depending on the point that it occurs and the specific types of nerves that are affected. The classification of a neuropathy can also be from the disease of specific condition that causes it.

To understand the types of neuropathies, it is important to understand the nervous system of the body. As earlier noted, the nervous system is the overall control centre of the body, making interpretation of the body’s feelings and senses. It is broadly classified into two:

Central Nervous systems and the Peripheral nervous system: The central Nervous System (CNS) is made up of the brain and the spinal cord. The PNS, otherwise referred to as the Peripheral Nervous System (PNS) on the other hand consists of all the nerves that branch out either from the spinal cord or the brain to serve different body organs.

Somatic and Autonomic Nervous System: The somatic nervous system is responsible for the regulation of movement in the skeletal muscles while the autonomic nervous system, commonly referred to as the ANS is the one that controls involuntary processes of the body such as the heart rate, body temperature, perspiration and digestion.To get to the complex nervous system, the building blocks of the system are the neurons. The structure of the neuron is composed of a cell body and dendrites that are on the axon.

The extensions on the neuron are referred to as dendrites. Each neuron comes with a receiving part that is referred to as the dendrites, with the received signal being transmitted towards the cell body of the neuron as an electric impulse, terminating at a synapse where the electrical impulse is converted.

Peripheral Neuropathy


In this case, the nerve disorders are found outside the brain and spinal cord. The nerves outside the brain and spinal cord make the peripheral nervous system and are thus affected by a given disease or condition. This is the most common form of neuropathy that is documented and as such happens to affect the extremities of the body, especially nerves that serve the body extremities including the toes, the feet, the fingers arms and hands.

An image showing general areas that are affected in peripheral neuropathy

The peripheral nervous system is made up of three common types of nerves. These include:

Autonomic nerves – This helps in the regulation of body functions such as breathing, blood pressure and temperature among other functions

Motor Nerves – This are the nerves that control skeletal muscle function in the body

Sensory nerves – These are the nerves responsible for the sensory perception including heat or cold and pain.

The following neuropathies affect different body part and organs differently as illustrated below.

Autonomic neuropathy affects

Urinary tract

Heart and blood vessels

Digestive system

Eyes

Sex organs

Sweat glands

Lungs

Proximal neuropathy affects

Buttocks

Thighs

Legs

Hips

Focal neuropathy affects

Facial muscles

Eyes

Feet

Abdomen

Ears

Pelvis

Legs

Lower back

Chest

Thighs

In most cases the nerve disorders are noticed in the feet and legs where sensation is gradually lost and deteriorates with time, creeping upwards the toes to legs, fingers to hands and arms. The most common observation noticed with people suffering from peripheral neuropathies is a reduction in the feeling sensation that they have in their fingers.

The most telling signs of a lurking peripheral neuropathy problem include:

Numbness in the extremities of the body especially toes in the feet and fingers.

A shooting pain in the affected areas

Loss of coordination of different body activities

General muscle weakness

In recent times, the term proximal neuropathy has been adopted to specifically refer to nerve damage that occurs within the hips, buttocks and thighs, with the symptoms of the neuropathy being felt on the lower extremities.

Cranial Neuropathy

Cranial neuropathy is a term that generally refers to nerve damage that may affect any of the twelve cranial nerves that are present within the brain. These 12 cranial nerves are:

1. Olfactory

This nerve is specific in allowing the sense of smell to be appreciated.

2. Optic nerve

It helps transform vision into an input that can be interpreted by the brain through the eye.

3. Oculomoter nerve

This nerve functions mainly around the eye by rotating the eye and lifting eyelid and general muscles that surround the eye.

4. Trochlear

This is a motor nerve that is tasked on handling eye muscles and turning the eye.

5. Trigeminal

The largest cranial nerve and has sensory functions of the nose eyes, tongue and teeth. It is further divided into three nerves which are the mandibular ophthalmic and maxillary.

6. Abducent

This nerve is specific to the eye and helps in lateral turning.

7. Facial

This nerve is one that is responsible for the numerous facial expressions that are seen. Also it has acts as a nerve that transmits sensory information of touch on the face and sense of touch in the tongue too.

8. Vestibulocochlear

It is this nerve that helps in providing of balance in the body.

9. Glossopharyngeal

A nerve that is carries sensory information on the pharynx, tongue, taste buds, salivary glands, and palate to the brain. The nerve is also important in allowing for swallowing of food.

10. Vagus

This nerve serves the pharynx, esophagus, larynx, bronchi, trachea, a section of the heart and the palate. It is also this nerve that helps in tasting sense.

11. Spinal accessory nerve

It serves the spinal cord and for that it supplies the brain with information of the spinal cord. It a;lso allows for movement in the shoulders and around the neck.

12. Hypoglossal nerve

This nerve specifically helps in control of the muscles of the tongue.

There are two common types of neuropathies that have been shown to be very common. These two are optic neuropathy and the auditory neuropathy. The optic neuropathy refers to damage of the optic nerve which is important in the transmission of visual signals from the retina of the eye and into the brain for interpretation.

The auditory nerve on the other hand is quite important in the body as it functions as the nerve that transmits sound from the outside through the ears and into the brain. Any damage to either the optic nerve or the auditory nerve may result in pain in the organ that is used by the nerve, paralysis or even total loss of control of the organ being served by the cranial nerve.

The cranial neuropathy is named depending on the nerve that it affects. The symptoms that are observed of the neuropathy help determine the type of neuropathy that is observed. Cranial nerves control sight, hearing, smell, taste and facial movement. In the event that only a single cranial nerve manifests the neuropathy, the condition is referred to as cranial mono neuropathy.

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