Subthalamic stimulation in Parkinson disease: intraoperative predictive factors

BACKGROUND

High-frequency stimulation of the subthalamic nucleus (STN) is an effective treatment for advanced forms of Parkinson disease. Postoperative improvement of motor parkinsonian disability is known to depend on patient selection and surgical targeting.

OBJECTIVE

To determine which clinical and electrophysiological variables evaluated during the operation predict the postoperative clinical outcome of patients with Parkinson disease treated by bilateral high-frequency stimulation of the STN.

METHODS

Intraoperative clinical and electrophysiological data obtained in 41 patients with Parkinson disease who underwent bilateral implantation of electrodes for STN stimulation were correlated with the improvement in parkinsonian disability assessed 6 months after the operation.

RESULTS

The extent of STN neuronal activity recorded along the trajectory of the therapeutic electrode had no effect on the postoperative clinical outcome. The intraoperative improvement in segmental akinesia, but not rigidity, was predictive of the postoperative improvement in parkinsonian motor disability and reduction in daily levodopa-equivalent dosage. Parkinsonian motor disability scores assessed after surgery were lower in patients with intraoperative stimulation-induced dyskinesias than in those without stimulation-induced dyskinesias.

CONCLUSION

The improvement of segmental akinesia and the observation of dyskinesias provoked by stimulation during the operation predict the best postoperative effects of bilateral STN stimulation on parkinsonian motor disability.

Deep brain stimulation of the subthalamic nucleus for Parkinson's disease: a therapy approaching evidence-based standards

DBS of the STN is one of the most promising new therapies for the treatment of PD. However - like many other therapies for PD - the present stage of the scientific assessment does not yet suffice the rigid criteria of evidence-based medicine. Further studies should specifically address the questions of efficacy and side effects as well as the impact on quality of life.

[Variance in effects of subthalamic nucleus stimulation]

Chronic stimulation of subthalamus nucleus (STN) is effective in treating severe motor fluctuation and levodopa induced dyskinesia as well as parkinsonian motor symptoms. The improvement of peak-dose/diphasic dyskinesias of STN stimulation is considered to be due to the decrease in the daily dosage of antiparkinsonian drugs. However one report pointed out that STN stimulation improved directly levodopa induced dyskinesia. Moreover the timing of the improvement for levodopa induced dyskinesia is not yet obvious. In the present study, we have assessed variance in the latency of improvement of levodopa induced dyskinesia due to STN stimulation. In addition, we would clarify an issue which cite of STN stimulation improved parkinsonian symptoms and motor complication (motor dyskinesias and motor fluctuation). We have studied seven patients diagnosed with advanced idiopathic Parkinson's disease with motor fluctuations and levodopa induced dyskinesias. Before and after the implantation of stimulating electrode, patients were assessed by the Unified Parkinson's Disease Rating Scale and % 'OFF' motor state. The dosage of the antiparkinsonian medication was not modified for one month prior to implantation. Following implantation, dosage of the medication and strength of stimulation was adjusted, if necessary. Symptoms of motor fluctuation and dyskinesia improved in all patients six month after surgery. The mean off-time duration and dyskinesia disability improved compared with presurgical conditions. However, the time course of the improvement of dyskinesias was not the same among patients. Contralateral limb dyskinesias in three patients improved immediately after the stimulation without modification of medication. In contrast, the stimulation worsened contralateral limb dyskinesias in other three patients immediately following the surgery. In two of the three patients, dyskinesias gradually improved within one month after surgery without reducing the dosage of medication. Dyskinesias of the other patient improved following a reduction in the dosage of medication one month after the surgery. Improvement of parkinsonian symptoms of the patients with longer latency of stimulation effect for dyskinesias was better than that of the patients with shorter latency. Stimulation cite of the former group appeared to locate more central than that of the latter group. Latency and strength of the effects of STN stimulation are variable.

Factors influencing the therapeutic effect of muscle afferent block for oromandibular dystonia and dyskinesia: implications for their distinct pathophysiology

Oromandibular dystonia (OMD) is a focal dystonia manifested by involuntary masticatory and/or lingual muscle contractions. Muscle afferent block (MAB) by injecting anaesthetic and alcohol intramuscularly is recently used for the treatment of OMD. To study the factors affecting the efficacy of MAB, 44 patients with OMD were treated by local injection of lidocaine and ethanol. They were divided into four groups (spastic, rhythmic, dyskinetic, and task-specific) according to the pattern of incisal movement and involuntary contraction. We used a clinical scaling protocol in terms of four parameters (mastication, speech, pain, and discomfort) to evaluate the change of symptoms objectively. The relationship of improvement in clinical scores with various parameters was assessed statistically. The overall objective improvement was 60.2 +/- 29.5%. The scores decreased significantly (P<0.0001, paired t-test) after MAB. The maximal incisal velocity significantly correlated inversely with the clinical improvement, and MAB was particularly effective for spastic contraction. Dyskinetic and rhythmic groups showed variable and significantly less improvements than the spastic group. MAB is highly effective for OMD, but not for the patients with dyskinetic symptoms. The jaw movement pattern is an important factor for predicting the outcome. The difference in the response to MAB in OMD and oral and/or orofacial dyskinesia suggests the distinct pathophysiology between the two.

Which factors influence therapeutic decisions in Parkinson's disease?

Development of dyskinesia is a common phenomenon during the long-term course of Parkinson's disease. During the last few years, some but not all pathogenetic mechanisms causing dyskinesias in PD have become better understood. Severity of Parkinson's disease and levodopa dosing are the main clinical risk factors. Most concepts underline the significance of pulsatile D1-receptor stimulation for the development of dyskinesias. The interactions between D1- and D2-mediated STR-Gpi pathways and colocalized neuropeptides are important but not fully understood. Glutamatergic overactivity might also be a significant pathogenetic factor. According to these pathophysiological concepts, therapeutic strategies focus mainly on continuous postsynaptic DA-receptor stimulation by long-acting DA-agonists or highly selective D2-agonists. Another strategy is the use of NMDA antagonists.

Cellular replacement therapy for Parkinson's disease--where we are today?

The concept of replacing lost dopamine neurons in Parkinson's disease using mesencephalic brain cells from fetal cadavers has been supported by over 20 years of research in animals and over a decade of clinical studies. The ambitious goal of these studies was no less than a molecular and cellular "cure" for Parkinson's disease, other neurodegenerative diseases, and spinal cord injury. Much research has been done in rodents, and a few studies have been done in nonhuman primate models. Early uncontrolled clinical reports were enthusiastic, but the outcome of the first randomized, double blind, controlled study challenged the idea that dopamine replacement cells can cure Parkinson's disease, although there were some significant positive findings. Were the earlier animal studies and clinical reports wrong? Should we give up on the goal? Some aspects of the trial design and implantation methods may have led to lack of effects and to some side effects such as dyskinesias. But a detailed review of clinical neural transplants published to date still suggests that neural transplantation variably reverses some aspects of Parkinson's disease, although differing methods make exact comparisons difficult. While the randomized clinical studies have been in progress, new methods have shown promise for increasing transplant survival and distribution, reconstructing the circuits to provide dopamine to the appropriate targets and with normal regulation. Selected promising new strategies are reviewed that block apoptosis induced by tissue dissection, promote vascularization of grafts, reduce oxidant stress, provide key growth factors, and counteract adverse effects of increased age. New sources of replacement cells and stem cells may provide additional advantages for the future. Full recovery from parkinsonism appears not only to be possible, but a reliable cell replacement treatment may finally be near.

Dyskinesias and grip control in Parkinson's disease are normalized by chronic stimulation of the subthalamic nucleus

Deep-brain stimulation of the subthalamic nucleus appears to reduce levodopa-induced dyskinesias, but whether this effect is caused by the reduction of the total levodopa ingestion or represents a direct effect on the motor system is unknown. Precision grip force of grasping movements and levodopa-induced dyskinesias was analyzed in 10 parkinsonian patients before and after 3 months of deep-brain stimulation of the subthalamic nucleus. Peak grip force was abnormally increased before surgery in the off-drug state and, particularly, in the on-drug state (sensitization). This grip force upregulation normalized with chronic deep-brain stimulation in both conditions (desensitization). Peak-dose dyskinesias also improved, and off-dystonia was completely abolished. Mean dosage of dopaminergic drugs was reduced, but force overflow and dyskinesias were equally improved in 2 patients without a reduction. Despite the same single levodopa test dose, force excess and levodopa-induced dyskinesias were drastically reduced after 3 months of deep-brain stimulation of the subthalamic nucleus. This indicates that direct effects of deep-brain stimulation of the subthalamic nucleus on levodopa-induced dyskinesias are likely to occur. Grip force overflow is a promising parameter to study the desensitizing effect of chronic deep-brain stimulation on levodopa-induced dyskinesias.

Consequences of oral rehabilitation on dyskinesia in adults with Down's syndrome: a clinical report

The aim of this article is to demonstrate that the presence of orofacial dyskinesia is often owing to underlying facial dysmorphology in persons with Down's syndrome. A series of cases is presented where orofacial dyskinesia was successfully treated by therapy establishing occlusal stability. The diagnosis of dyskinesia owing to dysmorphology should be precluded before any link with the degree of intellectual disability or neurological deficit is presumed. A multidisciplinary approach may be necessary to diagnose and treat these patients.

Pallidal deep brain stimulation in patients with cervical dystonia and severe cervical dyskinesias with cervical myelopathy

OBJECTIVES

Surgical treatment of complex cervical dystonia and of cervical dyskinesias associated with cervical myelopathy is challenging. In this prospective study, the long term effect of chronic pallidal stimulation in cervical dystonia and on combining the technique with spinal surgery in patients with severe cervical dyskinesias and secondary cervical myelopathy is described.

METHODS

Eight patients with a history of chronic dystonia who did not achieve adequate benefit from medical treatment or botulinum toxin injection participated in the study. Five patients had complex cervical dystonia with tonic postures and phasic movements. Three patients had rapidly progressive cervical myelopathy secondary to severe cervical dyskinesias and dystonia in the context of a generalised movement disorder. Quadripolar electrodes were implanted in the posteroventral lateral globus pallidus internus with stereotactic CT and microelectrode guidance. In the three patients with secondary cervical myelopathy, spinal surgery was performed within a few weeks and included multilevel laminectomies and a four level cervical corporectomy with spinal stabilisation.

RESULTS

Improvement of the movement disorder was noted early after pallidal surgery, but the full benefit could be appreciated only with a delay of several months during chronic stimulation. Three months after surgery, patients with cervical dystonia had improved by 38% in the severity score, by 54% in the disability score, and by 38% in the pain score of a modified version of the Toronto western spasmodic torticollis rating scale. At a mean follow up of 20 months, the severity score had improved by 63%, the disability score by 69%, and the pain score by 50% compared with preoperatively. There was also sustained amelioration of cervical dyskinesias in the three patients who underwent spinal surgery. Lead fractures occurred in two patients. The mean amplitude needed for chronic deep brain stimulation was 3.8 V at a mean pulse width of 210 micros, which is higher than that used for pallidal stimulation in Parkinson's disease.

CONCLUSIONS

Chronic pallidal stimulation is effective for complex cervical dystonia and it is a useful adjunct in patients with cervical dyskinesias and secondary cervical myelopathy who undergo spinal surgery.

Surgical and nonsurgical treatment options in patients with movement disorders of the platysma

PURPOSE

Movement disorders of the platysma may constitute both an aesthetic and a functional problem for the affected patients, who almost always have hyperkinesis. This article describes the different treatment options for movement disorders of the platysma.

PATIENTS AND METHODS

The therapeutic options that we used involved surgical and nonsurgical strategies (33 patients), including neurectomy of the cervical branch of the facial nerve, myectomy of the platysma, and the injection of botulinum toxin A. After therapy, patients were evaluated through self-assessment of the clinical outcome, clinical examination, and electromyography.

RESULTS

All patients showed improvement or complete alleviation of their symptoms. The data also showed that resection of the cervical branch of the facial nerve after its anterograde neurolysis may be performed during facial nerve reconstruction.

CONCLUSIONS

The various nonsurgical and surgical strategies are suitable for the treatment of different forms of platysmal movement disorders.

[Deep brain stimulation therapy for involuntary movements]

During the last decade, it has become clear that deep brain stimulation (DBS) therapy provides a dramatic improvement in the symptoms of movement disorders. We have experienced DBS in 110 patients with various types of involuntary movements, and confirmed the benefits of stimulation of the thalamic nucleus ventralis intermedius (Vim), internal globus pallidus (GPi) and subthalamic nucleus (STN) in these patients. DBS therapy affords the best effect on tremor when the Vim is selected as the stimulation site. DBS therapy is also useful for controlling rigidity when the GPi or STN is stimulated. Improvements of bradykinesia and gait disturbance are often induced by DBS therapy involving the GPi or STN. Dopa-induced dyskinesia can be attenuated effectively by the direct and/or indirect effects of DBS therapy. DBS of the Vim also provides excellent control of post-stroke involuntary movements, including hemiballism and hemichoreoathetosis. Dystonia in young patients is controlled effectively by DBS of GPi. Ablative procedures for control of involuntary movement disorders, such as thalamotomy and pallidotomy, always carry a risk associated with creating additional lesions in an already damaged brain. In contrast, there is not such a risk in DBS therapy. This modality of therapy is an important option in treating involuntary movements.

Bilateral GPi DBS is useful to reduce abnormal involuntary movements in advanced Parkinson's disease patients, but its action is related to modality and site of stimulation

In Parkinson's disease (PD) patients, internal globus pallidus (GPi) stimulation has been reported to produce good effects on abnormal involuntary movements (AIM); less improvement has been observed in extrapyramidal symptoms. We assessed the effect of monopolar dorsal (uppermost), ventral (lowest) and bipolar (uppermost vs. lowest) bilateral globus pallidus stimulation by quadripolar electrode on extrapyramidal symptoms and AIM induced by a dose of apomorphine. Six PD patients were studied in OFF therapy condition after surgery without stimulation (STIM OFF) and during stimulation (STIM ON) with the three different modalities. All patients were evaluated by the unified Parkinson's disease rating scale, section III (UPDRS) and by the AIM. Our results show that all three bilateral GPi stimulation modalities reduce the UPDRS score (between 49.7 and 31.5%), although the bipolar and lowest stimulation are the most effective. Similarly, bipolar and lowest stimulation were also the most effective in reducing the occurrence and intensity of the apomorphine-induced AIM. On the contrary, uppermost stimulation (UP ON) produced an AIM occurrence similar to that observed in the OFF stimulus condition. We suggest that bilateral GPi stimulation is an useful procedure to ameliorate extrapyramidal signs of advanced PD patients; however, it produces an antidyskinetic effect only if the ventral or the entire GPi is stimulated. On the contrary, the UP ON, most probably located in the external globus pallidus (GPe), does not modify the AIM occurrence.

Prosthetic dentistry in the treatment of movement disorders: dyskinesias and other neurological abnormalities

As long as the scope of dentistry is limited to teeth and supporting structures, their care and repair, probably no body of medical knowledge can be considered more traditional. However, a number of muscular and neurologic phenomena have been related to the dentition: unconventional dental prosthetic therapy has been shown to be effective in the treatment of temporomandibular joint disorders and movement disorders such as spontaneous orofacial dyskinesia and tardive dyskinesia. Although only anecdotal, the above results and an unanticipated event that occurred in one case of dystonia muscolorum deformans question everything that had been previously assumed about the limits of dentistry.

[Treatment of dyskinetic disorders with tremor by lesioning and DBS of Vim]

OBJECTIVE

To explore the effect of stereotactic operation in treatment of dyskinetic disorders with tremor as the main symptom and to study the value of anatomic location and microelectrode functional location.

METHODS

Surgiplan system and microelectrode direction technique were used to locate the Vim, and then target lesioning and deep brain simulation (DBS) were performed in 22 patients with dyskinetic disorders with tremor. After the operation, a follow-up was conducted for 6 approximately 12 months.

RESULTS

After the operation, tremor disappeared in 21 patients and hypermyotonia was improved in 13 cases. During the follow-up tremor completely disappeared in 18 patients, including 3 cases treated with DBS, was markedly alleviated in 3 cases and was slightly improved in one case. Typical cell firing at tremor was recorded in 17 cases during the operation.

CONCLUSION

The surgiplan system and microelectrode recording technique play an important role in location of Vim. Accurate location is crucial for success of operation. The curative effect of DBS is similar as lesioning operation.

[Symptomatology of movement disorders in children]

Abnormal involuntary movements are common symptoms in children. The neuroanatomical basis for these movement disorders is the extrapyramidal system. Although present at rest they may be more intensive during the will - depending motor activity and increased under stress. They are almost absent during sleep. The underlying causal factors of involuntary movement disorders include metabolic disorders, progressive neurodegenarative diseases, central nervous system infection. The symptomatology of chorea, athetosis, dystonia, tremor, myoclonus and tics are discussed. Special attention is paid to differential diagnosis of myoclonus, chorea and tics as well as to movement disorders and epilepsy.

Functional mapping of the human globus pallidus: contrasting effect of stimulation in the internal and external pallidum in Parkinson's disease

Our objective was to elaborate a functional map of the globus pallidus by correlating the intrapallidal localization of quadripolar electrodes implanted in parkinsonian patients with the clinical effect of the stimulation of each contact. Five patients with L-DOPA-responsive Parkinson's disease presenting severe motor fluctuations and L-DOPA-induced dyskinesias were treated by continuous bilateral high-frequency stimulation of the globus pallidus. The effects of stimulation on parkinsonian disability were tested through each of the four stimulating contacts of each electrode. The anatomical localization of each of the stimulating contacts was determined by confronting the pre- and post-operative magnetic resonance imaging with the anatomical atlas of Schaltenbrand and Wharen.(34) The registration procedure comprised digitization of the atlas, the use of deformation tools to fit atlas sections with magnetic resonance imaging sections, and three-dimensional reconstruction of both the atlas and the magnetic resonance imaging sections. Analysis of the 32 stimulating contacts tested did not reveal a somatotopic organization in the pallidal region investigated but demonstrated that high-frequency stimulation had contrasting effects depending on whether it was applied to the external or the internal pallidum. Akinesia was improved by stimulation of the external pallidum but worsened by stimulation of the internal pallidum. In contrast, parkinsonian rigidity was improved by stimulation of either part of the pallidum. The areas in the internal pallidum where stimulation worsened akinesia were those in which stimulation reduced or suppressed L-DOPA-induced dyskinesias. Conversely, stimulation applied to the external pallidum induced dyskinesias. The fact that rigidity was improved by stimulation of the internal and external pallidum suggests that the neuronal bases of parkinsonian rigidity are different from those of akinesia and dyskinesias. The effect on akinesia and dyskinesias is in agreement with the current model of basal ganglia circuitry(10) if high-frequency stimulation activates rather than inhibits pallidal neurons, a possibility which is very likely since there are marked anatomical, biochemical and electrophysiological differences between the globus pallidus and the subthalamic nucleus. This study demonstrates that high-frequency stimulation of the globus pallidus in parkinsonian patients has contrasting effects depending on whether it is applied to the external or the internal part of this nucleus. The effect on akinesia and dyskinesias suggests that stimulation activates pallidal neurons, a result which challenges the generally accepted concept that high-frequency stimulation inactivates neurons in the region stimulated.

Deep brain stimulation of the subthalamic nucleus for control of extrapyramidal features in advanced idiopathic parkinson's disease: one year follow-up

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) with a quadripolar electrode was carried out in 9 patients with advanced idiopathic Parkinson's disease (PD) affected with severe diurnal motor fluctuations. The effect of bilateral STN stimulation was evaluated by clinical methods in all patients after 3 and 12 months. Assessment was based on the Unified Parkinson's Disease Rating Scale (UPDRS), timed motor tests, the Schwab and England Activities of Daily Living and a diary chart to document motor fluctuations. Alterations in parkinsonian signs, motor performance and functional outcome were recorded postoperatively (1) under temporary complete withdrawal of both STN stimulation and medication; (2) in the presence of STN stimulation only; and (3) in the presence of both STN stimulation and medication. The results were compared with the preoperative data assessed in defined on-phase and defined off-phase. STN stimulation on (compared to STN stimulation off) results in a significant improvement in UPDRS motor scores: after 3 months from 50.5 +/- 14.3 to 27.8 +/- 5.8, and after 12 months from 49.4 +/- 14.1 to 27.1 +/- 7.1 (p < 0.01). There was a significant decrease in the average duration of off-periods from 8.82 +/- 2.47 hours to 1.00 +/- 1.06 hours (p < 0.001), a marked increase in on-periods without dyskinesia from 4.62 +/- 2.72 to 14.62 +/- 1.51 hours (p < 0.01), and a sharp drop in on-periods with dyskinesia from 2.87 (+/- 4.18) to 0.25 (+/- 0.97) hours (p < 0.05), which remained stable up to 12 months (off-periods: 1.25 +/- 1.58 hours, p < 0.001; on-periods without: 13.87 +/- 1.95 hours, p < 0.001; and on-periods wth dyskinesia: 0.37 +/- 1.06 hours, p < 0.05). However, our first PD patient with an implanted DBS electrode within the STN died from cardiac infarction two days after surgery. This sudden death was not linked either to surgery nor to stimulation - and happened by chance. Our findings confirm that STN stimulation is a suitable functional neurosurgical procedure for the modulation and control of PD signs associated with severe motor fluctuations, in that they demonstrate a beneficial effect which was fully sustained over a one year follow-up period.

KEYWORDS

Subthalamic nucleus, deep brain stimulation, Parkinson's disease.

Correlation of neurological manifestations and MR images in a patient with Wilson's disease after liver transplantation

Orthotopic liver transplantation (OLT) has been applied to patients with Wilson's disease (WD) for correction of irreversible liver cirrhosis. However, the neurological outcome and the correlation between clinical manifestations and neuroimage findings after OLT remain uncertain. We present a WD patient who showed an improvement in both liver functions and neurological manifestations after OLT. Serum levels of ceruloplasmin and copper returned to normal rapidly after the operation. His ataxic gait was improved 5 months later and dysmetria and tremor disappeared 11 months later. The high signal intensities on T2-weighted brain magnetic resonance images regressed at bilateral thalami 5 months later and disappeared in bilateral thalami and red nuclei 16 months after OLT. We conclude that the neurological improvement could be expected in WD patients after OLT. The improvement was correlated with the MRI changes in red nuclei and bilateral thalami.

Bilateral subthalamic nucleus stimulation in a parkinsonian patient with preoperative deficits in speech and cognition: persistent improvement in mobility but increased dependency: a case study

We report a patient with advanced Parkinson's disease, including severe and frequent off periods with freezing of gait, moderate dysphonia, and some cognitive impairment, who underwent bilateral subthalamic nucleus (STN) stimulation. The patient was followed for 1 year after surgery, showing persistent good mobility without off periods and without freezing, which reverted completely when stopping the stimulation. There was deterioration of cognition as well as increased aphonia and drooling, all of which remained when the stimulation was turned off. The striking improvement in motor symptoms following STN stimulation was not paralleled by improvement in disability, probably as a result of a cognitive decline, suggesting a diagnosis of Parkinson's disease with dementia. We conclude that chronic STN stimulation is efficient in alleviating akinetic motor symptoms including gait freezing; this surgery should be offered before patients start to exhibit speech or cognitive disturbances.