the dendrites of neurons that detect pain and initi-
ate transmission of pain signals to the CENTRAL
NERVOUS SYSTEM. Neurogenic pain often follows an
injury (traumatic or surgical) for which pain is a
reasonable symptom. However, when the injury
heals, the nociceptors can remain hypersensitive
to stimuli, particularly touch and temperature,
which they perceive as painful, and the nocicep-
tors continue to initiate pain signals. Neurogenic
pain often accompanies degenerative neurologic
conditions such as MULTIPLE SCLEROSISand pain syn-
dromes such as trigeminal NEURALGIAand COMPLEX
REGIONAL PAIN SYNDROME.
The sensation of neurogenic pain is characteris-
tically that of a persistent tingling, burning, or
“pins and needles” feeling. Some people also feel
sharp stabs of pain. The diagnostic path typically
includes evaluation of other potential causes for
the pain in the context of any history of a muscu-
loskeletal injury or neurologic condition. Diagno-
sis is often clinical (based on symptoms) after the
doctor has assessed or ruled out possible condi-
tions that could account for the symptoms.
MEDICATIONS TO TREAT NEUROGENIC PAIN
amitriptyline baclofen
carbamazepine dantrolene
desipramine fluoxetine
gabapentin paroxetine
phenytoin sertraline
tizanidine valproic acid
Because neurogenic pain results from NERVOUS
SYSTEMdysfunction, conventional ANALGESIC MED-
ICATIONSsuch as NONSTEROIDAL ANTI-INFLAMMATORY
DRUGS (NSAIDS) and narcotics are not especially
effective for providing pain relief. Low-DOSEtri-
cyclic ANTIDEPRESSANT MEDICATIONSand antiseizure
medications often do provide relief, apparently
through their influence on BRAINneurotransmit-
ters. Selective serotonin reuptake inhibitor (SSRI)
antidepressants are also effective in some people.
These medications may cause potentially serious
side effects, especially antiseizure medications.
Treatment may control pain until the underlying
condition improves or may be a long-term thera-
peutic process, depending on the cause of the dys-
function.
See also NEURON; NEUROTRANSMITTER; NOCICEPTOR;
PSYCHOGENIC PAIN.nociceptor A specialized molecule on the den-
drite of a sensory NEURONthat interprets stimuli as
PAINand activates NERVEfibers (C fibers and A-
delta fibers) to send pain signals to the CENTRAL
NERVOUS SYSTEM. Nociceptors activate the with-
drawal REFLEX—the sudden, involuntary move-
ment to get away from the stimulus such as
jerking one’s hand from a hot surface. Sensory
neurons often have extensive networks of den-
drites, the branchlike fibers that extend from the
nerve body to draw input into the neuron. Noci-
ceptors pepper these dendrites, serving as one of
the body’s most primal warning mechanisms of
danger from physical harm. They respond to sen-
sations of heat, cold, sharp, and pressure.
TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION
(TENS), a pain relief method, uses mild electrical
current to stimulate nociceptors. Researchers
believe this either restores the neuron’s normal
perceptions of stimuli or overloads the neuron so
that it cannot transmit pain signals. Doctors
believe counterirritants such as capsaicin topical
ointment work in a similar fashion. Some Western
researchers believe ACUPUNCTURE’s effectiveness for
pain relief comes from its ability to stimulate or
block nociceptor function; Western doctors often
combine electrical stimulation with acupuncture
to intensify this effect.
For further discussion of nociceptors, please see
the overview section “Pain and Pain Management.”
See alsoALTERNATIVE METHODS FOR PAIN RELIEF;
ANALGESIC MEDICATIONS; DERMATOME; PROPRIOCEPTION;
SPINAL NERVES; TRADITIONALCHINESE MEDICINE(TCM).nociceptor 381