The sodium channel members found in small nerve fibres are Na v1.7 (SCN9A), Na v1.8 (SCN10A), and Na v1.9 (SCN11A). The pathophysiology is unknown but may be related to dysregulation of voltage gated sodium channels with hyperexcitability of dorsal root ganglion neurons. Familial amyloid polyneuropathy (transthyretin).Sodium channelopathy (SCN9A most common, also SCN10A and SCN11A).Antibiotics (metronidazole, nitrofurantoin, linezolid, isoniazid).
Alcohol (this can eventually cause large fibre neuropathy) (3%). Diabetes mellitus and glucose intolerance (up to 20% of cases). The small unmyelinated nerves are affected. It is histopathologically characterized by degeneration of small nerve fibre endings. SFN is a generalised sensory nerve disease process with abnormalities in the structure and function of affected nerve fibres. Polymodal Muscle and Skeletal Mechanoreceptorsĭisorders known to contribute to SFN are listed below. Overview of different nociception receptors with corresponding small nerve fibre type Receptor TypeĬutaneous and subcutaneous mechanoreceptors "slow" pain, touch, pressure temperature (and postganglionic autonomic). AMH type I for rapid mechanical pain (high heat threshold >53C), AMH type II for rapid heat pain (lower heat threshold 43-47C). "rapid" pain, crude touch, pressure, temperature. Touch, pressure (and gamma motor neurons) Proprioception, muscle spindle primary endings (Ia), golgi tendon organs (Ib) (and alpha motor neurons)ĭiscriminative mechanoreception (touch, vibration), proprioception, pain modulation (block nociceptive information, allodynia in sensitisation) The large fibres in contrast are the Aβ afferents from the skin, muscle, and internal organs and the α motor neurons.Ĭharacteristics of sensory nerve fibres Nerve fibre Small fibre nerves also include the γ efferent fibres, and the preganglionic and postganglionic sympathetic C fibres. The majority of peripheral sensory nerves are unmyelinated C fibres and thinly myelinated Aδ fibres. Small fibre neuropathy results from damage to the nociceptive system. Nerve Anatomy See also: Basic Neurophysiology 6.5.1 Water-induced and EMLA-induced Skin Wrinkling.
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