Puin, 44 (1991) 285-288 ,I: 1991 Elsevhx Science Publishers ALX2ivlS 030439599 100090B 285 B.V. ~304-3959~91,‘$~3.50 PAIN 01769 Disappearance of thalamic pain after parietal subcortical stroke Emilio D. Soria and Edward J. Fine A hypertensive man had a long standing history of contumacious hyperpathia in the right upper Summa~ extremity, resistant to medical therapy, secondary to a Iacunar infarct in the left thalamus. A second cerebrovascular accident caused a small lesion in the left corona radiata, interrupting the thalamoparietal interconnections, and terminated the pain instantly. Interruption of the subcortical parietal white matter may more effectively control pain than cortical lesions. A few surgeons have successfully treated rebellious chronic pain with stereotaxic operations in the corona radiata, resulting in lesions very similar to our patient’s This overlooked and nearly forgotten technique may still have value in treating selected cases. Key words: Intractable pain; Thalamic diseases: Cerebrovascular The disappearance of a chronic pain following a cerebral lesion is exceedingly rare. In 1911, Head and Holmes [6] described a case in which a phantom limb pain disappeared after an infarct of the opposite parietal lobe. Only few other simifar cases have been reported [2]. We have observed a case in which thalamic pain caused by a lacunar infarct in the thalamus subsided after a second infarct in the corona radiata. This case suggests that a small lesion in the white matter which destroys the thalamoparieta1 radiations may be more effective in abolishing a contralateral chronic pain than extensive cortical damage. Case report A man with a 10 year history of arteriaf hypertension had a cerebra-vascular accident at age 62, which caused a right hemiparesis and a right hemisensory syndrome. Over the next year, he developed severe hyperpathia in the right hemibody, particularly in the entire upper Correspondence to: Dr. Emilio Veterans Admimstration Medical KY 40206-1499. LJ.S.A. D. Soria, MD, Neurology Service. Center. 800 Zorn Ave., Louisville, disorders, Parietal lobe extremity and the upper part of the chest. The pain was constant, but fluctuated in intensity, at times becoming excruciating. It consisted of superficial waves of ‘smarting ache’ and a deep seated burning sensation, causing profund psychological distress with bouts of agitation. The exacerbations were often induced by various stimuli. such as touch and cold, movements of the right hand, and even the mere thought of being touched. He became very vigilant towards the right side of his body, and adopted the habit of wearing 2 or 3 gloves to fend off any stimuli to the right hand. The right hand adopted a dystonic posture with a ‘swan neck’ appearance and showed choreoathetoid movements (Fig. 1). Despite the abnormal posture, the hand retained the ability to perform most movements. Chewing movements, reminiscent of tardive dyskinesia, were also noted. The examination of cranial nerves was normal, except for mild right facial weakness, and mild impairment of sensation to deep pressure in the right face. Visual fields were normal. The right upper extremity was difficult to evaluate because of the intense discomfort that he suffered when contracting his muscles or when being touched. but power appeared to be only mildly impaired. There was obvious clumsiness and ataxia in the right hand. Tendon reflexes on the right were slightly brisker than the left. He had a right Babinski sign. There was diminution of pain and temperature sensation in the entire right half of his body, particularly in the upper limb and the upper part of the right hemithorax. Vibration, deep pressure, postural sense, and appreciation of passive movements were mildly diminished in the right upper limb. The threshold for pain, temperature and light touch was increased, but, when exceeded, the stimulus became unbearable. Somatosensory evoked potentials to right median nerve stimulation showed a complete absence of N18. N20 and P27 peaks on the scalp; the N13 and the P13/14 remained intact. Somatosensory evoked potentials in the contralateral side were normal. A CT scan of the head (Fig. 2), done 1 year after the stroke, showed a small hypodense round lesion, consistent with a lacunar infarct in the right thatamus. The lesion was sharply marinated and non-enhancing and caused no mass effect. Later scans showed no change in the appearance of the lesion. Fig. 2. CT scan of the head shows a lacunar thaiamus (arrow). infarct in the left During the rnsuing 6 yars he was tt-~ited .tl rirff,, ent times with tricyciic antidepressants. rnrld narc‘sqrch. salicyfatos, non-steroidal ~inti-inflamrnatr,r\ :rgents. c;ir. bamazepine. phenytoin and baclofcn. 7’ht: t~~~r~agcrrwtrt of these drugs and their side effects prompted multiple admissions to our racility. The benefit ?~h~aincd uith any of these drugs wab only marginal. When ‘1 new drug was started. there often was a short pcr~od 4~1‘trnpr(lvcment. hut the pain alwavs returned unat~atetf. In addition, psych~~therap~, behavior ~~~~~d~~~c~iti[~~~ snd trunk cutaneous electric nerve sti~llu~ati~~f~ ~li”rc used. i,ttr several years he remained very disabled hv tht~ pain and his former cheerful mood deteriorarcd 10 &rctmc dcpression. However, 7 years after the initial ~tr.ok~: he had it second ictus. He suddenly had powerlessness of the right arm and leg, though remaining fully conscious. His speech became garbled and he was unable to walk. He was admitted to another institution I;-tr 1 month. From the onset of his second ictus. the chronic pain disappeared completely. When he was seen in our hospital 5 months fater, he was found to have a right hemiparesis, p~~rtic~~i~lr~~ dense in the upper extremity. ‘The previously noted athetoid posturing of the right hand had been replaced by the typical contractures of chronic spasticit?. There was no hemianopsia and the speech had rcturnrd to normal. The sense of touch was very disturbed in the entire right hemihody. The pain and temperature sense was also greatly diminished. being most affected in the right upper extremity. Deep pressure, joint position, vibration. graphesthesia and double simultaneous stimu- Fig. 3. An infarct is present (arrow\) in the left parietal region, 2x7 lation were undisturbed or mildly affected. There was no spontaneous pain or hyperesthesia, and rubbing the right upper extremity caused no unpleasant sensations. He stated that despite the loss of motor function in his right limbs, the quality of his life had greatly improved due to the absence of the chronic pain. A CT scan of the head (Fig. 3) showed a low density lesion, well demarcated, which was not present in previous CT scans. The lesion was located in the left parietal lobe, deep in the centrum semiovale, adjacent to the body of the lateral ventricle. This lesion has not changed in a CT scan performed months later. He has been followed in our chnic for approximatety one year after the second ictus and he has remained stable. without recurrence of the thalamic pain. Discussion The role of the parietal Iobe in the perception of pain is poorly understood. Surgical removal of the sensory areas of the parietal lobe has been tried in cases of contralateral chronic pain with very limited success. The excision of the part of the postcentral gyrus corresponding to the painful area is often followed by an immediate disappearance of pain. However, most authors have reported a tendency for the recurrence of the painful syndrome within several months [23]. In 1937, Leriche [8] first suggested the surgical ablation of the sensory cortex for the treatment of chronic pain, and in 1949 he injected procaine into the postcentral gyrus of a patient suffering from severe thalamic pain: the initial relief only lasted 2 months [9]. ~utierrez-Mahoney [5] first performed postcentral cortectomy for the treatment of pain. Penfield and Welch (151 abolished thalamic pains with postcentral gyrectomy but the results were not permanent and the pains gradually returned. Spiegel et al. [19] also stated that in their experience removal of the sensory cortex had no effect on thalamic hyperpathia. Other authors have obtained better results [4.20]. The failures were often attributed to insufficient cortical excision, particularly if not including the accessory (secondary) somatosensory area of Penfield, considered by many to be a specific area of the cortex to which pain fibers project [If. Other authors have speculated that the spinothalamic tract has a bilateral cortical connection [21]. The cortical representation, even if unilateral, may be too widely distributed as to be abolished by cortectomies or strokes [22]. Penfield and Jasper [14] expressed the view that pain is sensed at the thalamic and not the cortical level. Penfield [12] stated that ‘. . . no removal of cortex anywhere can prevent pain from being felt _. . _’ However, painful sensations have been elicited with electrical stimulation of the parietal cortex [13]. Epileptic seizures can have an aura of pain [lo] and lesions of the parietal cortex can result in analgesia [ 111, Until recently there was no experimental evidence of cortical regions being driven by peripheral noxious stimuli. However, it has been found that neurons responding to noxious stimuli in the ventral posterior lateral (VPL) nucleus can be backfired from areas of the primary somatosensory cortex [7]. A complex circuitry involving both the thalamus and the cortex permits a variety of synaptic interactions needed for the perception of pain 117,241. The parietal lobe is also directly connected with all other lobes of the brain through association pathways that may also be necessary for the elaboration of the painful experience. Interruption of the subcortical white matter, strategically localized at the crossroads of this complex circuitry may be a more useful tactic than wide cortical resection. Actually, this procedure has been successfully used by several surgeons. Talairach et al. 1211 in 1960 performed stereotaxic interruption of the thalamoparietal radiation in the corona radiata with good results. In 7 out of 8 cases subjected to this procedure, complete relief of the pain was achieved. Riechert [1X] also employed a similar technique. Pool and Bridges [16] treated phantom pain with parietal leukotomies. Cassinari et al. [3] destroyed the thalamoparictal radiations with radioactive yttrium in 2 cases. These subcortical lesions appear to yield better results than parietal cortectomies. Modern techniques in the medical and surgical armamentarium against chronic pain have made parieta1 cortectomy obsolete. The complete resolution of pain in our case and the good surgical results with little morbidity offer the consideration of stereotaxic destruction of the thalamoparietal radiations as a valid alternative if pain is unresponsible to more conventional therapies. References 1 Biemond, A., The conductton of pam above the level of the thalamus opticus, Arch. Neurol. Psychiat.. 75 (1956) 231-244. 2 Bornstein, B.. Sur Ie phenomene du memhre fant?mc, Encephale. 38 (1949) 32-46. 3 Cassinari, V., Pagni. C.A.. Infuse. L. and Marossero, F.. La chirurgia stereotassica dei dolori incoercibili. Esperienza personale a proposito di 20 casi. Sist. New., I6 (1964) 17-28. 4 Ertckson. T.C., Bleckwenn, W.J. and Woolsey. C.N.. Observations on the post-central gyrus in relatton 10 pain, Trans. Am. Neural. Ass.. (1952) 57-59. 5 Gutierrez-Mahoney. C.G.. The treatment of phantom limb by removal of post-central cortex, J. Neurosurg.. 1 (1944) 156162. 6 Head, H. and Holmes, Cr.. Sensory disturbances from cerebral lesions, Brain. 34 (191 I) 1022254. 7 Kenshalo. D.R.. Giesler. C.J.. Leonard, R.B. and Willis, W.D.. Responses of neurons in primate ventral posterior laterat nucleus to noxious strmuli, J. Neurophysiol., 43 (1980) 1594-1614. 8 Leriche, R., La Chirurgie de la Douleur. Edn. 1. Masson. Paris. 1937. 428 pp. Y teriche, R., La Chirurgie de la Douleur. Edn. 3, Masson. Pa&. 1949. 472 pp. 10 Lewin. W. and Phillips, C.G., Observations on partial removal of the postcentral gyrus for pain, J. Neural. Neurosurg. Psychiat.. 15 (1952) 143.-147. 11 Marshall, J., Sensory disturbances in cortical wounds with special reference to pain. J. Neural. Neurosurg. Psychtat.. 14 (1951) 1X7-204. 12 Penfield. W., Some observations on the cetebral cortex of man. Proc. Roy. Sot. B. 134 (1947) 329-347. 13 Penfield. W. and Boldrey, E.. Somatic motor and sensory representation in the cerebral cortex of man as studied hy electrical stimulation, Brain, 60 (1937) 389-443. 14 Pmfield, W. and Jasper, Ii., Epilepsy and the Functional Anatomy of the fiuman Brain, Little, Brown, Boston, MA, 1954. pp. 41-154. 15 Penfield, W. and Welch, K. The supplementary motor area of the cerebral cortex: a clinical and experimental study. Arch. Neural. Psychiat.. 66 (1951) 289-317. 16 Pool. J.L. and Bridges, T.J.. Subcortical parietal lobotomy for relief of phantom limb syndrome in the upper extrernity: a case report, Bull. NY Acad. Med., 30 (1954) 302-309.