INVOLUNTARY MOVEMENTS FOLLOWING STEREOTACTIC OPERATIONS FOR PARKINSONISM WITH SPECIAL REFERENCE TO HEMI-CHOREA (BALLISMUS)

Hemiballismus: current concepts and review

Hemiballism is a rare movement disorder characterized by a high amplitude movement of an entire limb or limbs on one side of the body. The acute development of hemiballismus is often caused by focal lesions in the contralateral basal ganglia and STN. Many etiologies exist for this rare disorder with vascular causes and nonketotic hyperglycemia being the most common. Clearer understanding of the pathophysiology of hemiballism has led to important insights into the function and interaction of structures within the basal ganglia. Newer models of basal ganglia function have been proposed based on the study of the pathophysiology of hemiballism. Prognosis is favorable for most patients with complete resolution with or without treatment. Medical and surgical treatments are often successful in reducing or completely ameliorating the movements in those patients with more severe movements.

Subthalamic nucleotomy alleviates parkinsonism in the 1 -methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP)-exposed primate

Research into the neural mechanisms underlying the symptoms of parkinsonism utilizing the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-exposed primate model have shown that the subthalamic nucleus (STN) occupies a central role. As a logical development of this theory, we have studied the effects of thermocoagulative lesions of the STN in the primate model. Such lesions can cause remarkable symptom reversal in the experimental primate model.

Toxin-Induced Movement Disorders

Toxins can be cited as a cause of several movement disorders, but this association is rare and the resultant syndromes usually include additional signs that are not typical for the idiopathic movement disorders. Most instances of confirmed toxin-induced movement disorders show lesions on CT and MRI scans of cortical or subcortical structures. A common underlying element in these toxin-induced syndromes is the development of lesions primarily in the pallidum and striatum. Because many toxins result in lesions affecting these structures, a selective vulnerability to hypoxic or metabolic insults has long been postulated. The susceptibility of these structures may relate to a number of factors, including the pattern of oxidative metabolism, heavy metal concentration, vascular perfusion, and neuronal innervation. Finally, in addition to causing disability, certain neurotoxins have led to a better understanding of human disease through the development of research models. As an example, the MPTP model has not only provided an animal model to study therapeutic strategies in PD but has also contributed important insights into the mechanism of neuronal degeneration.

Treatment of hemiballismus with stereotactic pallidotomy

Hemiballismus is a relatively rare movement disorder that is characterized by uncontrolled, random, large-amplitude movements of the limbs. It is usually caused by a vascular lesion that involves the contralateral subthalamic nucleus (STN) (also known as the nucleus hypothalamicus or corpus luysi) and its afferent and efferent pathways.

The authors present a case of medically intractable hemiballismus in a 70-year-old woman who was successfully treated with stereotactic posteroventral pallidotomy. In agreement with the data reported earlier by other groups, the microrecording performed during the pallidotomy showed a decreased rate of firing of the pallidal neurons, supporting the theory of impaired excitatory input from the STN to the internal part of the globus pallidus.

Stereotactic pallidotomy may be the procedure of choice in the treatment of medically intractable hemiballismus. Intraoperative microrecording significantly improves the precision of the stereotactic targeting and should be considered a standard part of the pallidotomy protocol.

The subthalamic nucleus, hemiballismus and Parkinson's disease: reappraisal of a neurosurgical dogma

The subthalamic nucleus (STN) currently is considered to play a key role in the pathophysiological origin of the parkinsonian state and is therefore the main target for surgical treatment of Parkinson's disease. The authors review the incidence of hemichorea/ballism (HCB) as a complication of thalamotomy, pallidotomy or campotomy procedures before the introduction of levodopa therapy, including the few reported cases accompanied by a neuropathological study. The literature shows that only a small number of parkinsonian patients with HCB had a lesion of the STN. Preliminary data in Parkinson's disease patients submitted to a subthalamotomy with current functional stereotaxy also indicate that HCB is a very rare complication. To explain this observation, we suggest that the parkinsonian state is characterized by an increased threshold for the induction of dyskinesia following STN lesioning. This arises as a consequence of reduced activity in the 'direct' GABA projection to the globus pallidus medialis (GPm) which accompanies dopamine depletion. Lesioning of the STN reduces excitation of the GPm, and theoretically this should induce dyskinesias. However, an STN lesion also, simultaneously, further reduces the hypoactivity in the globus pallidus lateralis (GPl) that is a feature of Parkinson's disease, and hence may compensate for GPm hypoactivity, thus self-stabilizing basal ganglia output activity and reducing the risk of HCB. We conclude that lesioning of the STN in Parkinson's disease is a feasible approach in some circumstances.

The treatment of posttraumatic tremor by stereotactic surgery. Symptomatic and functional outcome in a series of 35 patients

The authors report the long-term results of stereotactic surgery for severe posttraumatic appendicular tremor in 35 patients. The tremors developed after severe head trauma in 33 patients (94%) and after mild to moderate head trauma in two (6%). In all but one, the tremor was most evident during activity. The amplitude of the kinetic tremor was greater than 5 cm in 33 patients (94%) and greater than 12 cm in 19 patients (54%). All were severely incapacitated in their daily living activities due to the tremors. The 35 patients underwent 42 stereotactic operations; five patients were reoperated on the same side and two were treated with a bilateral staged procedure. The contralateral zona incerta was the stereotactic target in 12 patients and was targeted in combination with the base of the ventrolateral (oroventral) thalamus in 23 patients. Long-term postoperative follow-up review was obtained in 32 patients (mean follow-up period 10.5 years). Persistent improvement of tremor was noted in 88%. The tremor was absent or markedly reduced in 65%. Functional disability was assessed and quantified with a modified form of an established rating scale for patients with tremor; it was reduced from a mean value of 57% of maximum disability to 37% over the long term (p < 0.001). Follow-up lesion assessment was obtained in 18 patients by multiplanar magnetic resonance imaging and at autopsy in one patient whose death was unrelated to surgery. As in previous studies, the frequency of persistent side effects was relatively high (38%). These consisted mainly of aggravation of preoperative symptoms. The results are compared to those of a total of 55 patients reported from 1960 to 1992. The occurrence of dystonia and dystonic postures is discussed. Stereotactic surgery is a powerful tool to alleviate posttraumatic tremor and to improve functional disability. However, as there is considerable risk of persistent morbidity in patients after severe head trauma, the operation should be restricted to selected cases with disabling tremor.

Spontaneous hemiballism and disappearance of parksinsonism following contralateral lenticular lacunar infarct

Hemiballism was observed in a 77-year-old woman with Parksinson disease after a contralateral lenticular infarct without apparent involvement of the subthalamic nucleus. Parkinsonian signs ipsilateral to the hemiballism remained abolished despite subsequent nearly complete recovery from the hyperkinesias. It is argued that clinical events were due to a single ischemic lesion of the putamen-pallidum complex.

Meige's syndrome: clinical, pharmacological and radiological observations

The clinical pharmacological, and neuroradiological observations in six patients with spontaneous blepharospasm-oromandibular dystonia (Meige's) syndrome are recorded. This group consisted of five males and one female, mean age at onset being 50.3 years. The duration of symptoms ranged from three months to 12 years, three patients having had symptoms for over four years. The dyskinesia was arrhythmic and asymmetrical in the orbicularis oculi and masseter muscles electrophysiologically. Pharmacological studies evinced no consistent response to parenteral physostigmine, no response to oral levodopa and no significant improvement in the dyskinesia following oral haloperidol. Lumbar air encephalogram was done in five patients, and showed frontal cortical atrophy without ventricular dilation in three. It is concluded that Meige's syndrome is a distinct nosological entity, and that physostigmine test is unlikely to be helpful in the differential diagnosis from neuroleptic-induced tardive dyskinesia. Neurotransmitter imbalance in the basal ganglia in this disorder remains to be established, and at present there is no satisfactory drug treatment for this progressively disabling movement disorder.