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• Continuous, burning pain
  
  
• Shooting or lancinating pain/sharp, tearing pain
  
  
• Electric, shock-like pain
  
  
• Allodynia (pain from a stimulus that is not always painful)
  
  
• Hyperalgesia (an increased response to a stimulus that is normally painful)
  
  
• Paraesthesia (abnormal, but not unpleasant, sensations caused by spontaneous ectopic discharge along Aß fibres. Such sensations may occur in the absence of external stimuli)
  
  
• Dysaesthesia (abnormal and unpleasant sensations caused by spontaneous ectopic discharges along Aß fibres. Such sensations may be spontuneous or evoked)
  

Patients with the same neuropathic pain syndrome often present with very different symptoms and respond to the same therapy with varying degrees of success, thus complicating disease management. It has become clear that physicians should adopt a more symptom- and disease mechanism-based approach to selecting therapy.

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Common Neuropathic Pain Syndromes

Postherpetic neuralgia is a neuropathic pain syndrome that occurs following an acute attack of herpes zoster (shingles). It is defined as pain persisting for more than 3 months after the active herpes zoster lesions have healed, and involves constant aching, burning or itching with intermittent, severe, lancinating pain. Allodynia and hyperalgesia may also occur.

Peripheral or painful diabetic neuropathy is a peripheral, autonomic or cranial nerve disorder associated with diabetes mellitus. These conditions usually result from diabetic microvascular injury involving small blood vessels that supply nerves. It is estimated that over 50% of diabetic patients may experience a neuropathy during their lifetime, although not all neuropathies are painful. Painful neuropathy is generally described as superficial and affects the feet and hands. Burning, tingling and allodynia are typically reported.

Trigeminal neuralgia affects any of the 3 trigeminal nerves that supply either side of the face, and can sometimes affect 2 branches at once. The 1-sided pain of trigeminal neuralgia may extend through the cheek, mouth, nose and/or jaw muscles. This condition is characterized by a lancinating, shooting, electric-like sensation that can last from a few seconds to several minutes. Pain may be initiated by stimulating trigger points on the face, lips or gums, or by facial muscle movement, such as chewing.

Sciatica is characterized by pain radiating from the back into the buttock and into the leg. The pain may travel below the knee and may also involve the foot. Lower leg muscles may become numb or weak. Sciatica is most commonly caused by prolapse of the intervertebral disc. This term is also used to describe pain anywhere along the sciatic nerve.

Post-stroke pain is a common, severe central pain condition. It is characterized by pain in body areas that have lost sensory innervation due to disruption of the spinothalamic tract as a direct result of the stroke.

Complex regional pain syndrome describes a variety of syndromes that may follow injury, commonly to an extremity. Patients describe their pain as constant, burning, aching and throbbing, and this may be combined with autonomic and tissue changes at the injury site. The pain usually begins days to weeks after the injury, and persists beyond the time normally expected for the injury to heal. The pain tends to radiate to an entire anatomic region, such as the distal leg and foot. This group of symptoms has also been referred to as "reflex sympathetic dystrophy" or, in the case of a known nerve injury, "causalgia".

Cancer pain can be nociceptive, neuropathic or mixed in nature. Neuropathic pain in cancer patients can occur via various mechanisms, such as by nerve compression or injury caused directly by the tumour, or by cancer treatments, such as chemotherapy. Common symptoms include spontaneous burning pain, intermittent sharp or stabbing pain, hyperalgesia and allodynia.

Painful upper limb describes a range of painful syndromes affecting the upper limbs, such as carpal tunnel syndrome and tennis elbow. Carpal tunnel syndrome is caused by compression of the median nerve in the hand as it passes through the carpal tunnel, a narrow passage in the wrist comprised of bone and the transverse carpal ligament. Overuse, injury, friction, fractures, fluid retention and forceful movements are common causes. One of the first symptoms of carpal tunnel syndrome is numbness in the hand, thumb, index finger and middle finger, soon followed by pain in the same area.

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