Doctors classify pain into various categories, but there are two main types of persistent pain.
nociceptive pain, results from damage to tissues, as from arthritis or a burn. It is usually described as sharp, aching, or throbbing pain.
· neuropathic pain, results from damage to the nerves themselves and is often set off by diseases like diabetes or shingles.
Nerves connect the spinal cord to the rest of the body and allow the brain to communicate with the skin, muscles and internal organs. Nutritional unbalance, alcoholism, toxins, infections or auto-immunity can cause painful neuropathies from diseases such as kidney failure. Neuropathic pain may be caused by pressure on a nerve or a group of nerves. People often describe this pain as a burning or heavy sensation, or numbness along the path of the affected nerve. The cause of a neuropathic pain remains unknown in a third of the cases.
Numerous reasons and complexities exist with a pain condition. Some arise from one single condition or injury whilst others are due to a combination of conditions and causes.

It is worth remembering that nociceptive and neuropathic pain are not mutually exclusive of each other and in some conditions like Sciatica will co-exist.

Many other types of pain are also described.

• Allodynia
• Anaesthesia dolorosa
• Anginal pain
• Breakthrough pain
• Complex Regional Pain Syndrome I
• Complex Regional Pain Syndrome II
• Hyperalgesia
• Hyperpathia
• Idiopathic pain
• Malignant pain
• Paresthesia
• Phantom limb pain
• Psychogenic pain

Allodynia
means “other pain” and refers to:
· Pain caused by stimuli which are not normally painful
Pain occuring at a site area other than the area stimulated.
Location transfer is not synonymous with referred pain which transfers pain to areas representative of the embryonic position of nerves.

Anaesthesia dolorosa:
is one of the most severe complications of neurosurgery and is considered to be non-reversible. It occurs when a nerve normally the trigeminal nerve, is damaged by surgery or physical trauma in such a way that the feeling sensation in part of the body is reduced or eliminated entirely while the sense of pain remains.

Breakthrough pain:
unanticipated aggravation or worsening of pre-existing chronic pain for which a person is undergoing regular treatment may result in breakthrough pain needing adjustments in treatment to obtain relief.Such pain usually comes on quickly and may last anything from a few minutes to many hours. Readjustment of analgesic doses is necessary along with the modification of physical activities.

Complex Regional Pain Syndrome 1: (Reflex Sympathetic Dystrophy)
a chronic pain condition that is believed to be the result of dysfunction in the central or peripheral nervous systems. Typically there are dramatic changes in the colour and temperature of the skin over the affected limb or body part together with intense burning pain, skin sensitivity, sweating, and swelling. Often triggered by tissue injury, the term CRPS 1 refers situations where the patient has these symptoms with no identifiable underlying nerve injury. The pain does not correspond to the distribution of a single nerve and it is worsened by movement.

Complex Regional Pain Syndrome II: (Causalgia)
is a burning type of pain associated with a partially damaged peripheral nerve. The pain extends beyond the distribution of the nerve and results due to abnormal connections which develop during healing between various nerves. The skin of the person affected is classically cold, moist and swollen, becoming atrophic later.

Hyperalgesia:
a condition of altered perception such that stimuli which would normally induce a trivial discomfort cause significant pain. Hyperalgesia is often a component of a neuropathic pain syndrome

Hyperpathia:
a condition of altered perception arising from the repetitive and prolonged stimulation of neurons by a stimuli which would normally be innocuous in short isolated bursts but when repeated or prolonged results in severe explosive or persistent pain.yperpathia is often a component of a neuropathic pain syndrome

Idiopathic pain:
is a diagnosis of pain which is suffered by a patient for longer than 6 months, for which there is no physical cause and no specific mental disorder.

Malignant pain:
pain associated with diseases like cancer caused by the tumour affecting the surrounding tissues, most commonly bone tumours. The pain can be either due to the disease itself or due to the treatment given for cancer like surgery, radiotherapy and chemotherapy. The pain needs to be carefully assessed and appropriately treated

Paresthesia:
a sensation of tingling, pricking, or numbness of a person’s skin with no apparent long-term physical effect, more generally known as the feeling of pins and needles or of a limb being “asleep
Transient paresthesia is a temporary tingling, pricking, or numbness of the skin — “pins and needles usually due to inadvertent pressure placed on a superficial nerve. It is normally experienced in the extremities (hands, arms, legs, or feet), but can also occur in other parts of the body. The sensation gradually goes away once the pressure on the nerve is relieved.
Chronic paresthesia indicates a problem with the functioning of nerve cells, or neurons or may arise due to direct damage to the nerves themselves, or neuropathy.

Phantom limb pain:
refers to the severe pain and tingling sensation which continue to be experienced from the perceived existence of the limb which has be amputated. It commonly arises in cases where the amputation is delayed after the initial injury. The perceived limb may be felt to be felt to be lying in an abnormal and uncomfortable position. Damage to nerve endings play an important part in this condition with the resulting erroneous regrowth of nerve tissue triggering abnormal and painful discharge of neurones in the stump, and there is often a change in the way that nerves from the amputated limb connect to neurones within the spinal cord.

Psychogenic pain:
is entirely or mostly related to a psychologic disorder where a person has persistent pain with evidence of psychologic disturbances and but no evidence of a disorder that could cause the pain.
It should be noted that it is very rare for pain to be purely psychogenic and more commonly, the pain has a physical cause but the degree of pain is out of proportion with what most people with a similar disorder experience.

Any kind of pain can be complicated by psychologic factors. The fact that the pain is caused or worsened by psychologic factors does not mean that it is not real. Most people who report pain are really experiencing it, even if a physical cause cannot be identified. Pain complicated by psychologic factors still requires treatment, often by a team that includes a psychologist or psychiatrist. As with other kinds of treatment for chronic pain, the treatment for this type of pain varies from person to person, and doctors try to match the treatment with the person’s needs. For most people who have chronic psychogenic pain, the goals of treatment are to improve comfort and physical and psychologic function. Doctors may make specific recommendations for gradually increasing physical and social activities. Drugs and nondrug treatments—such as biofeedback, relaxation training, distraction techniques, hypnosis, transcutaneous electrical nerve stimulation (TENS), and physical therapy—may be used. Psychologic counselling is often needed.

Allodynia