Sensory abnormalities in consecutive, unselected patients with central post-stroke pain

Abstract

This study examined the sensory abnormalities in an unselected, consecutive group of patients with central post-stroke pain (CPSP) surviving more than 1 year after stroke. The sensory examination included clinical examination and quantitative measures with detection and pain thresholds to heat and cold stimuli, argon laser, von Frey hair and determination of stimulus-response function in the 10-45 degrees C range. Sensory examination was in 11 identified CPSP patients (5 female, 6 male; aged 43-80 years) carried out in the painful area using the contralateral homologue area as reference. Pain rating was performed using the McGill Pain Questionnaire and a VAS scale. All patients had ischemic (MRI verified) infarction. Of the 11 patients with supratentorial lesions, 5 had thalamic lesions; in addition, 7 patients had lesions in the brain stem/cerebellum. Median present spontaneous pain intensity on the VAS scale was 3.3 (range: 0-7.7). All patients had pain in the body part with sensory abnormalities, which in 8 patients extended the area with pain. Warm detection threshold was higher in the pain area in all patients, and all except 1 patient had increased cold detection threshold. Cold and heat pain thresholds were raised as well, but to a lesser degree. Sensibility to touch (von Frey hairs) and pain (argon laser) were changed in only 4 and 3 patients, respectively. A stimulus-response curve in the 10-45 degrees C range showed different patterns compared to the non-affected side. A cold allodynia in the 10-45 degrees C range was present in the painful area in 6 (56%) of the patients. The results support the theory that damage to the spino-thalamo-cortical pathway is a necessary condition in CPSP. It is proposed that the spontaneous pain in CPSP is linked to hyperexitability or spontaneous discharges in thalamic or cortical neurons that have lost part of their normal input.

Lesions Limited to the Human Thalamic Principal Somatosensory Nucleus (Ventral Caudal) Are Associated with Loss of Cold Sensations and Central Pain

“…Among patients in whom quantitative sensory testing was performed, two had cold and warm hypoesthesia bilaterally (patients 13 and 18), consistent with evidence of abnormal thermal sensation ipsilateral to the stroke in patients with CPSP Vestergaard et al, 1995). Patient 3 demonstrated no abnormality of innocuous cold sensation and the smallest Vc-only lesion, which suggests that sensory impairment depends on a minimal lesion volume in Vc (Table 3) (Duncan et al, 1993).…”

“…These patients were selected from a group of patients with central pain or sensory abnormalities referred to Dr. Lenz. CPSP or central dysesthesia syndrome was diagnosed by an indisputable stroke episode and by exclusion of other nociceptive or neuropathic mechanisms of the pain or dysesthesias (Beric et al, 1988;Casey, 1991;Vestergaard et al, 1995;Boivie, 1999). Patients had radiologically identified lesions of the posterior thalamus contralateral to their symptoms but no other lesions of the pain or somatosensory systems, as broadly defined (Mountcastle, 1984;Davis, 2000;Rainville et al, 2000).…”

“…Central pain is often described in terms both of thermal stimuli, such as burning, and of pain evoked by cold or tactile stimuli that are not normally painful (allodynia) Vestergaard et al, 1995). On quantitative somatic sensory testing, patients with CPSP exhibit diminished thermal and pain sensations, modalities that are largely mediated through the STT Greenspan et al, 2004).…”

“…Some studies have identified lesions that may be limited to ventral caudal (Vc) (Hirai and Jones, 1989;Leijon et al, 1989;Vestergaard et al, 1995;Bowsher et al, 1998). One case report used atlas-based mapping of magnetic resonance images to locate a stroke involving a large part of Vc and sparing VMpo (Montes et al, 2005).…”

Deconstructing Central Pain with Psychophysical and Neuroimaging Studies

“…When studied by quantitative sensory testing (QST, Table 1), patients with central poststroke pain (CPSP) exhibit hypoesthesia for cold in 85-91% of patients, for warmth in 85-100%. Decreased sensation for pain (hypoalgesia) is found for cold pain in roughly 45% of patients, and for heat pain in 7-91% Leijon et al, 1989;Andersen et al, 1995;Vestergaard et al, 1995;Greenspan et al, 2004). As shown in Table 1, CPSP patients show decreased tactile sensibility in 27-52% of cases.…”