J. Neurosurg. / Volume 31 / August, 1969

Effects of Stimulating or Destroying the Deep Cerebellar Regions in Man

BLAINE S. NASHOLD, JR., M.D., AND D. GRAHAM SLAUGHTER, M.D. Department oJ Surgery, Division oJ Neurosurgery, Duke University Medical Center, Durham, North Carolina

ITUATED deep within the paramedian out careful thought and consideration as to region of the cerebellum lies a constel- the safety of the patient. The use of this tech- S lation of nuclei that relay cerebellar in- nique was begun over 5 years ago and has fluences throughout the central nervous sys- been used successfully in evaluation of pa- tem. The dentate, which is the largest of tients with intractable epilepsy, involuntary these nuclei in man, was first described in movements and painful syndromes. The Duke 1685 by VieussenY 9 It relays chiefly the ef- Medical Center Committee on Human Ex- ferent outflow from the lateral hemispheric perimentation has scrutinized the techniques area of the cerebellum, exerting its influence and clinical results during this time. The pa- on the tone and movement of the ipsilateral tients are admitted to a special research ward limbs. 1,~,~4,25 Experimental dentate lesions where the evaluation takes place. Each pa- result in hypotonia, dysmetria, and, in some tient and his family are carefully and fully cases, tremor. 1,~,24 Recently, neurosurgeons informed as to the risks involved, and it is have attempted to ablate the dentate in per- stressed that the primary reason for the tech- sons with extreme hypertonia and involun- nique is to improve the localization of the tary movements. We have developed stereo- therapeutic lesion for the individual patient. taxic coordinates for the cerebellar nuclei in order to explore the paramedian cerebellar Case Reports regions by electrical stimulation with a view Case 1. A 19-year-old girl with bilateral of assessing the therapeutic possibilities of congenital athetosis was born prematurely cerebellar nuclear lesions. 26 with a birth weight of 2 pounds. Athetosis This report concerns the effects of electri- was diagnosed in infancy. In 1966, a stereo- cal stimulation and high frequency lesions in taxic high frequency (HF) lesion was made the regions of paramedian cerebellar struc- in the right prerubral field of Forel, with no tures. improvement in the athetosis. In 1967, three electrodes were implanted stereotaxically into Method the region of the left medial and intermedi- Five of six patients with either gross in- ate portions of the dentate nucleus (Table voluntary movements, tremor, or spasticity 1). Stimulation of the dentate facilitated the were evaluated by implanting chronic elec- ipsilateral athetoid movements. Eight HF le- trodes into the paramedian cerebellar region sions were made in the region of the left me- (Table 1). In five patients, high frequency dial and intermediate portions of the dentate lesions were made in the region of the inter- nucleus (Table 2). Postoperatively the athe- positus and dentate nuclei in an effort to re- toid movements were reduced, there was hy- lieve hypertonia, tremor, or the involuntary potonia, and the patient was able to carry movements (Table 2). The motor disorders out limited voluntary movements in the left studied included those of two patients with arm without interference by the athetoid congenital athetosis, two with intention movements. tremor, one with heredofamilial tremor, and one with a syndrome of flexor spasticity and Case 2. A 25-year-old woman with bilat- arm tremor. eral congenital athetosis was diagnosed in The implantation of chronic electrodes in infancy. When examined in 1967 she was the brain of humans was not undertaken with- confined to a wheel chair by severe general- Received for publication April 18, 1968. ized athetoid movements. The athetosis re- Revision received January 28, 1969. stricted all of her voluntary movements, but 172 Study of Cerebellar Nuclei 173 TABLE 1 Estimated location of deep cerebellar electrodes in five patients

Case Distance of Electrode from No. Diagnosis Cerebellar Midline Estimated Location of Electrode Athetosis 3 electrodes lateral interposit us/medial dentate. 8-10 mm (left) intermediate dentate 10.11 mm (left) 10.12.5 mm (left) Athetosis 2 electrodes 7-9 mm (right) brachium conjunctivum to medial 9-10 mm (right) dentate, medial dentate Heredofamilial tremor 5 electrodes 6 mm (left) brachiumconjunctivum, 9 mm (left) medial dentate, 3.5 mm (right) brachiumand interpositus, 9.5 mm (right) medial dentate, 10-11 mm (right) intermediate dentate Post-traumatic cerebellar 3 electrodes ataxic tremor 21-22 mm (right) lateral dentate, 21-22 mm (right) lateral dentate, 20-22 mm (left) lateral dentate Multiple sclerosis with 3 electrodes tremor 9-10 mm (tight) medial dentate, 12 mm (right) intermediate dentate, 10-13 mm (left) intermediate dentate she could type and communicated in this planted bilaterally in the depths of the cere- way. Chronic electrodes were implanted in bellum. Two were on the left in the region of the region of the right brachium conjunc- the brachium conjunctivum and the medial tivum and right medial and intermediate dentate nucleus. Three were on the right, portions of the dentate nucleus (Table 1). one in the brachium conjunctivum, and the Stimulation facilitated the ipsilateral athetoid other two in the medial portion of the den- movements (Table 2). Four HF lesions tate nucleus (Table 1). Following the plac- were made in the region of the right bra- ing of the implants a condition of cerebellar chium conjunctivum and medial dentate nu- shock developed; it was global in nature, cleus. Postoperatively the right-sided athe- consisting of an immediate and profound toid movements were improved; there was generalized hypotonia, hyporeflexia, and hy- also a reduction of muscle tone in the right pokinesis, with absence of tremor. Deep ten- arm. Voluntary movements of her right arm, don reflexes were initially absent but weak hand, and fingers have continued to improve flexor plantar responses were preserved. In 2 for the last 8 months. days the muscle tone, deep tendon reflexes, and flexor movements began to return. His Case 3. A 21-year-old man started having head and eyes tended to be deviated to the tremor when he was 8 years old. There was right, and he could not open his eyes for sev- a familial history of tremor beginning in the eral days. This profound state of generalized teens. The patient's neurological findings in- cerebellar dysfunction seemed similar to the cluded slurred speech and nystagmus on lat- effects reported after total cerebellectomy in eral gaze. A tremor (6 per sec) involved animals. the palate, tongue, and arms (Fig. 1). Vol- The patient recovered in 2 weeks, and untary arm movement increased the tremor. electrical stimulations were carried out alter- Sensation, motor power, and deep tendon re- nately in the right and left dentate regions. flexes were normal. Five electrodes were ira- Stimulation of either medial dentate region