Neuropathy is a dysfunction of nerves leading to loss of sensation. Unlike pain that occurs in response to an injury, neuropathic pain (neuralgia) occurs without any associated stimulation. Description of neuropathic pain may vary.
Chronic pain sufferers with a neuropathic component experience worse quality of life, greater psychological stress, increased interference with sleep, and decreased ability to perform tasks.
Pathology: Neuropathic pain (neuralgia) is due to an abnormal activation of the nociceptive system without specifically stimulating the nociceptors. Neuroplastic changes in the central nervous system culminate in neuronal hyperexcitability. “Chronic pain sensitization” describes the characteristic of producing neuronal hyperexcitability with prolonged noxious stimulation.
A patient who presents neural symptoms is assessed according to the type of noxious pathway, the location of altered sensation (dysesthesia) within dermatome and myotome maps, relative strength of muscle contraction on both sides of the body, and the degree of sensitization from the spine.
The patient should be referred to a medical specialist when differential diagnoses indicate radiculopathy or other pathology that is not within the scope of practice.
There are two types of pathways that communicate noxious (pain) information to the brain:
Spinothalamic pathways (carry noxious information from below the head and neck)
Related disorders include thoracic outlet syndrome, sciatic nerve pain, radial tunnel syndrome, extensor tendinopathy, carpal tunnel syndrome, et al.
Trigeminothalamic pathway (carry noxious information from face, head and neck)
Related disorders include tension and migraine headaches, cervical myofascial pain syndromes, temporomandibular joint disorder and trigeminal neuralgia, and typically present increased tension in head and neck musculature.
Treatment for Neuropathic Pain
Apply modalities that affect the fibrosis or adhesions (thickening of connective tissue) that surround and compress nerves in the affected region, e.g. soft tissue, muscle energy, joint mobilization, ischaemic pressure, myofascial techniques, corrective exercise, stretches and self massage tools (e.g. lacrosse ball).
Nerve Fibre Types and Gate Control Theory
- Aδ nerve fibres conduct fast (acute, sharp) pain.
- Unmyelinated C nerve fibres conduct slow pain.
- Most non-nociceptive afferents are Aβ fibres.
Gate control theory postulates that the activity of a large diameter of Aβ afferents can prevent the transmission of noxious information, thereby decreasing the sensation of pain.
Treatment for Chronic Pain Sensitization
Apply modalities that activate Aβ afferents, e.g. Transcutaneous Electrical Nerve Stimulation (TENS), acupuncture.