pathophysiology of pain Flashcards
pain receptors
nociceptors
types of primary afferent fibres
a delta fibres - myelinated , for fast sharp pain
c fibres - unmyelinated , chronic pain
what does primary hyperalgesia describe
increased responsiveness to heat add mechanical stimulus at the site of injury
visceral pain ?
pain originating from the internal organs
what type of stimuli are associated with visceral pain
distention and ischemia
what is chronic pain ?
pain without apparent biological value that persists beyond tissue healing ( >3 months )
what is the suggested theory behind the development of chronic pain ?
wind up phenomenon, repetitive stimulation off c fibres ( central sensitization)
what is secondary hyperalgesia ?
hypersensitivity to pain in an area that is distant to the primary site of injury
what receptors play a role in the maintenance of chronic pain ?
NMDA receptors
what are the classifications of chronic pain ?
1- inflammatory pain - tissue is damaged by trauma or infection
2- neuropathic pain - pathology of the nervous
3- dysfunctional pain - poorly localised pain not caused by inflammation or nerve damage
what are examples of neuropathic pain
phantom limb
carpal tunnel
peripheral neeuropathy
central neeuropathy
examples of dysfunctional pain
fibromyalgia
irritable bowl syndrome
7 types of neuropathic pain
lumbar radicular pain
trigeminal neuralgia
post herpetic pain
complex regional pain syndrome
phantom limb
diabetic neuropathy
central pain syndrome
what is the CP of neuropathic pain
may be described as tingling, burning ,stabbing or numb sensation
associated with spontaneous pain without any stimulus
may be associated with allodynia or hyperalgesia
what is allodynia
the feeling of pain from a non painful stimulus
what is the cause of complex regional pain syndrome
usually triggeredd by an injury
what are thee different types off complex regional pain syndrome ?
CRPS I
CRPS II
old names for CRPS ?
type 1 - reflex sympathetic dystrophy
type 2 - causalgia
what is the difference between CRPS type 1 and 2 ?
type 1 - occurs after a minor fracture or injury to a limb without direct nerve injury
type 2 - after injury to a major peripheral nerve
what are the presenting symptoms of complex regional pain syndrome ?
continuing pain
allodynia
hyperalgesia
autonomic changes - hyperhydrosis or changes iin temperature
trophic skin changes
motor abnormalities
neglect like syndrome
+ sympathetically maintained pain
presentation of trigeminal neuralgia
neuropathic pain affecting the the eye, lips nose scalp or forehead
shooting sharp pain “electric shock like pain”
pain provoked by innoxious stimuli
what disease is commonly associated with trigeminal neuralgia ?
multiple sclerosis
what is thee cause off trigeminal neuralgia ?
due to microvascular loop compressing on the nerve
what tumor is commonly associated with trigeminal neuralgia ?
tumor arachnoid cysts in the
cerebellar cerebellopontine angle
