Long-term experience with intraoperative microrecording during DBS neurosurgery in STN and GPi

Intraoperative microelectrode recording (MER) for targeting during deep brain stimulation (DBS) procedures has been evaluated over a period of 4 years, in 57 consecutive patients with Parkinson's disease, who received DBS in the subthalamic nucleus (STN-DBS), and 28 consecutive patients with either dystonia (23) or Parkinson's disease (five), in whom the internal segment of the globus pallidus (GPi-DBS) was targeted. The procedure for DBS was a one-stage bilateral stereotactic approach using a combined electrode for both MER and macrostimulation. Up to five micro/macro-electrodes were used in an array with a central, lateral, medial, anterior, and posterior position. Final target location was based on intraoperative test stimulation. For the STN, the central trajectory was chosen for implantation in 50% of the cases and for the globus pallidus internus (GPi) in 57% of the cases. Furthermore, in 64% of the cases, the channel selected for the permanent electrode corresponded with the trajectory having the longest segment of STN MER activity. For the GPi, this was the case in 61%. The mean and standard deviation of the deepest contact point with respect to the magnetic resonance imaging (MRI)-based target for the STN was 2.1 +/- 1.5 mm and for the GPi was -0.5 +/- 1.2 mm. MER facilitates the selection of the final electrode location in STN-DBS and GPi-DBS, and based on the observed MER activity, a pre-selection could be made as to which channel would be the best candidate for macro-test stimulation and at which depth should be stimulated. The choice of the final location is based on intraoperative test stimulation, and it is demonstrated that regularly it is not the central channel that is chosen for implantation. On average, the target as defined by MER activity intensity was in accordance with the MRI-based targets both for the STN and GPi. However, the position of the best MER activity did not necessarily correlate with the locus that produced the most beneficial clinical response on macroelectrode testing intraoperativel

Clinical practice: evidence-based recommendations for the treatment of cervical dystonia with botulinum toxin

Cervical dystonia (CD) is the most frequent form of focal dystonia. Symptoms often result in pain and functional disability. Local injections of botulinum neurotoxin are currently the treatment of choice for CD. Although this treatment has proven effective and is widely applied worldwide, many issues still remain open in the clinical practice. We performed a systematic review of the literature on botulinum toxin treatment for CD based on a question-oriented approach, with the aim to provide practical recommendations for the treating clinicians. Key questions from the clinical practice were explored. Results suggest that while the beneficial effect of botulinum toxin treatment on different aspects of CD is well established, robust evidence is still missing concerning some practical aspects, such as dose equivalence between different formulations, optimal treatment intervals, treatment approaches, and the use of supportive techniques including electromyography or ultrasounds. Established strategies to prevent or manage common side effects (including excessive muscle weakness, pain at injection site, dysphagia) and potential contraindications to this treatment (pregnancy and lactation, use of anticoagulants, neurological comorbidities) should also be further explored

Clinical heterogeneity in newly diagnosed Parkinson's disease

OBJECTIVE: To determine clinical heterogeneity in newly diagnosed Parkinson's disease using cluster analysis and to describe the subgroups in terms of impairment, disability, perceived quality of life, and use of dopaminergic therapy. METHODS: We conducted a k-means cluster analysis in a prospective hospital based cohort of 133 patients with newly diagnosed Parkinson's disease. Variables selected for the cluster analysis were age of disease onset, age at the moment of examination, rate of disease progression, levodopa responsive PD symptoms and levodopa non-responsive PD symptoms, cognition (mini-mental state examination) and emotional functioning (hospital anxiety depression scale). In addition, the homogeneous subgroups identified were clinically validated using descriptive statistics. RESULTS: Cluster analysis with a two-cluster solution identified a younger and older age group. The three-cluster solution identified an intermediate group with respect to age. In both cluster solutions the older the onset group, the higher the progression rate and the level of motor impairments. The intermediate older onset group in the three cluster solution was characterized by more anxiety and depressive symptoms. Increasing age at disease onset was significantly associated with higher Hoehn and Yahr stages, level of disability and lower perceived quality of life. CONCLUSIONS: We hypothesize there are three distinct subgroups in patients with newly diagnosed PD: a younger onset group, an intermediate older onset group with more anxiety and depressive symptoms and an oldest onset group with more motor impairment and higher rate of progressio

Long-term follow-up of thalamic stimulation versus thalamotomy for tremor suppression

Thalamic stimulation and thalamotomy for treatment of tremor due to Parkinson's disease, essential tremor, and multiple sclerosis were compared in a randomized trial. The symptomatic and functional outcome was studied after 5 years of follow-up. Sixty-eight patients were treated (45 Parkinson's disease, 13 essential tremor, 10 multiple sclerosis) by thalamotomy (n = 34) or thalamic stimulation (n = 34). After 5 years, 48 patients were available for follow-up. The primary outcome measure was change in functional status measured by the Frenchay Activities Index (FAI), scores ranging from 0 to 60. Secondary outcome measures were tremor severity, frequency of complications, and patients' assessment of the outcome. The mean difference in FAI scores between thalamic stimulation and thalamotomy was 4.4 (95% CI: 1.1-7.7) after 6 months, 3.3 (95% CI: -0.03-6.6) after 2 years and 4.0 (95% CI: 0.3-7.7) after 5 years in favor of stimulation. Tremor suppression was equally effective after both procedures, and stable in Parkinson patients. In ET and multiple sclerosis, a diminished effect of stimulation was observed in half of the patients. There were six stimulation equipment-related complications, but neurological side effects of surgery were higher after thalamotomy. Subjective outcome-assessment by the patients was more favorable in the stimulation group. (C) 2008 Movement Disorder Societ

Course of cognitive decline in Parkinson's disease: a meta-analysis

A meta-analysis was conducted on 25 longitudinal studies involving 901 initially non-demented Parkinson's disease (PD) patients to examine the magnitude of decline across multiple cognitive domains associated with disease progression. Pooled effect sizes reflecting the standardized difference between baseline and follow-up neuropsychological performance were calculated for 8 cognitive domains using a random-effects model. Relatively small effect sizes were found across all cognitive domains (d = .00 - .40). During a mean follow-up interval of 29 months, significant declines were detected in global cognitive ability (d = .40), visuoconstructive skills (d = .32), and memory (d = .29). Age showed a significant relation with decline in global cognitive ability and memory. Lower educational level was associated with greater decline in all cognitive domains. Studies with longer follow-up intervals yielded larger effect sizes for global cognitive ability. In non-demented PD patients, changes in cognitive functions over time appear to be modest. Educational level, age, and length of the follow-up interval are likely to affect the magnitude of decline in several domains. Methodological flaws, such as selection bias and uncontrolled practice effects, may have caused underestimation of the true extent of declin

Multicenter study on deep brain stimulation in Parkinson's disease: An independent assessment of reported adverse events at 4 years

Ongoing adverse events (AEs) at 4-years postsurgery in 69 patients with advanced Parkinson's disease (PD) who received deep brain stimulation (DBS) of the subthalamic nucleus (STN) (n = 49) or the internal globus pallidus (GPi) (n = 20), in the framework of a subset of eight centers of a multicenter study, were analyzed by an independent ad hoc committee. At baseline, the patients' age, sex, disease duration, and clinical condition were virtually identical, as was the duration of follow-up. There were 64 AEs reported in 53% of STN DBS patients and eight AEs reported in 35% of GPi DBS patients. Most of the AEs were not deemed severe and were reported to be present "both with and without stimulation." The majority of the AEs affected patients' cognitive, psychiatric and behavioral status, as well as speech, gait, and balance, and most of these AEs occurred in STN DBS patients. When comparing patients who exhibited AEs with those who did not, it was found that in the STN DBS group, the patients with AEs had a longer disease duration, as well as more gait disorders and psychiatric disturbances at baseline

Local field potentials and oscillatory activity of the internal globus pallidus in myoclonus-dystonia

The pathophysiology of myoclonus-dystonia (MD), an autosomal dominantly inherited movement disorder characterized by myoclonic jerks and dystonic contractions, is largely unknown. In the present study, local field potential (LFP) activities in the globus pallidus internus (GPi) from two genetically proven M-D patients are investigated. Coherence analysis between GPi UP activity and electromyographic muscle activity (EMG) and synchronization of GPi neuronal activity using event-related spectral perturbation (ERSP) in a go-no-go paradigm were studied. Significant increased coherence in the 3 to 15 Hz frequency band was detected between GPi LFP activity and several muscles, with the LFP leading the muscles. The ERSP analysis revealed synchronization in the 3 to 15 Hz frequency band within the GPi before the imperative cue of the go-no-go task and desynchronization in the same band after the Cue. The LFP recordings of the GPi in M-D show that the low-frequency band previously described in dystonia is also involved in the dystonia plus syndrome M-D. The 3 to 15 Hz synchronization in the go-no-go paradigm has not been described previously and may point to the existence of (myoclonus-)dystonia specific oscillatory activity in the GPi. (C) 2007 Movement Disorder Society