title: Psychophysical and cerebral responses to heat stimulation in patients with central pain, painless central sensory loss, and in healthy persons.
abstract: Patients with central pain (CP) typically have chronic pain within an area of reduced pain and temperature sensation, suggesting an impairment of endogenous pain modulation mechanisms. We tested the hypothesis that some brain structures normally activated by cutaneous heat stimulation would be hyperresponsive among patients with CP but not among patients with a central nervous system lesion causing a loss of heat or nociceptive sensation with no pain (NP). We used H(2)(15)O positron emission tomography to measure, in 15 healthy control participants, 10 NP patients, and 10 CP patients, increases in regional cerebral blood flow among volumes of interest (VOI) from the resting (no stimulus) condition during bilateral contact heat stimulation at heat detection, heat pain threshold, and heat pain tolerance levels. Both patient groups had a reduced perception of heat intensity and unpleasantness on the clinically affected side and a bilateral impairment of heat detection. Compared with the HC group, both NP and CP patients had more hyperactive and hypoactive VOI in the resting state and more hyperresponsive and hyporesponsive VOI during heat stimulation. Compared with NP patients, CP patients had more hyperresponsive VOI in the intralaminar thalamus and sensory-motor cortex during heat stimulation. Our results show that focal CNS lesions produce bilateral sensory deficits and widespread changes in the nociceptive excitability of the brain. The increased nociceptive excitability within the intralaminar thalamus and sensory-motor cortex of our sample of CP patients suggests an underlying pathophysiology for the pain in some central pain syndromes.
authors: Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA Department of Physical Medicine and Rehabilitation, University of Michigan, Ann Arbor, Michigan, USA Neurology Research, Veterans Affairs Medical Center, Ann Arbor, Michigan, USA Faculty of Life Sciences, Hamburg University of Applied Sciences, Hamburg, Germany Department of Radiology, University of Washington, Seattle, Washington, USA.
authors: Kenneth L
authors: KL
authors: Casey
authors: Michael
authors: M
authors: Geisser
authors: Jürgen
authors: J
authors: Lorenz
authors: Thomas J
authors: TJ
authors: Morrow
authors: Pamela
authors: P
authors: Paulson
authors: Satoshi
authors: S
authors: Minoshima
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000502:physiology / Q000503:physiopathology*; D059350:Chronic Pain / Q000209:etiology / Q000503:physiopathology*; D004185:Disability Evaluation; D005260:Female; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D006930:Hyperalgesia / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination / Q000379:methods; D010147:Pain Measurement / Q000379:methods; D010812:Physical Stimulation / Q000379:methods; D049268:Positron-Emission Tomography / Q000379:methods / Q000592:standards; D011601:Psychophysics / Q000295:instrumentation* / Q000592:standards; D012678:Sensation Disorders / Q000209:etiology / Q000503:physiopathology*