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Periodic features of local field potentials (LFP) are extensively studied to establish the pathophysiological features contributing to Parkinson's disease (PD). Pathological LFP synchronization in the subthalamic nucleus (STN) was assumed to link with motor signs of PD. Commonly, the association between oscillations and clinical signs is studied while the patients are at rest. However, changes in LFPs during movement may reflect particular traits of motor processing in the basal ganglia under PD. Recently, the aperiodic 1/f broadband component of LFP spectra has attracted the attention of researchers because it may provide meaningful information about the neural activity in the brain. Here, we compared LFP signals in the STN of parkinsonian patients at rest and during hand movements occasionally followed by leg movements using two approaches, one of which accounts for the aperiodic features of LFP spectra. Using both methods, a significant increase was observed in synchronization in the low beta range during sequent leg but not hand movements. For either movement, there was a significant increase in gamma range synchronization using uncorrected power spectra and a significant decrease in the slope of the aperiodic component for the 1/f‐corrected method. These findings may support the claim that the 1/f slope possibly reflects the excitatory/inhibitory projections ratio in the recording site. Only the difference in the slope correlated significantly with motor signs of PD. These data show that the slope of aperiodic component may be a useful measure that is sensitive to the specific state and its changes in the brain. [ABSTRACT FROM AUTHOR]

Background: Dystonia is a heterogeneous group of movement disorders, which is specified by sustained or intermittent muscular contractions, causing involuntary abnormal movements and/or postures. Indications for neurosurgical treatment in dystonia include inefficacy/insufficiency of pharmacological treatment, widespread distribution of pathological movements, limitation in activities of daily living and self-service due to dystonic movements. Main clinical goal of the surgery is prevention of permanent disability and improving in the quality of life of dystonia patients. Objective: To analyze the experience of neurosurgical treatment of dystonia patients in Burdenko Neurosurgical Institute. Patients and Methods: 179 patients with different types of dystonia were operated in the period from 2003 to 2015: 56 patients with isolated (primary) generalized dystonia; 44 with isolated segmental dystonia; 41 with isolated focal/cervical dystonia; 7 with myoclonic or tremulous dystonia; 2 with basal ganglia calcification; 6 with the other neurodegenerative dystonia; 4 with tardive dystonia, 14 with dyskinetic cerebral palsy (CP); 5 with the other acquired dystonia. Disease duration ranged from 2 to 57 years; age at surgery ranged from 7 to 67 years. We assessed clinical outcome in patients with the minimum three-year follow-up available. Burke-Fahn-Marsden rating scale was used to evaluate dystonia severity. For cervical dystonia, TWSTRS and Tsui scales were applied. Postoperative changes in functional and motor state were assessed using Global outcome scale (GOS). Results: Majority of the patients with primary (isolated) dystonia received DBS GPi (134 patients, 95%). Ten of them had a history of previous stereotactic lesioning surgery. Main clinical improvement was observed in the first 6 months of DBS GPi. 86 patients were available for evaluation in long-term follow-up. Motor improvement in patients with generalized dystonia after 3 years was 59.7 ± 15.7%, in patients with segmental dystonia - 66.5 ± 17.5%, according to BFMDRS. In cervical dystonia, motor improvement after 3 years of DBS GPi was 55.5 ± 22.1%, according to TWSTRS, and 60.9 ± 19.9%, according to Tsui scale. 88% of patients had stable excellent or good motor and functional outcome in long-term follow-up (up to 12 years, GOS). Negative predictive factors for DBS GPi efficacy in primary dystonia appeared to be longer disease duration, earlier age of onset, and severity of motor impairment. Four patients required implantation of the second pair of GPi-electrodes for optimizing clinical outcome. One patient with previous thalamotomy underwent bilateral DBS STN with 66% improvement. In 6 patients with predominantly tonic pharmacoresistant cervical dystonia, selective peripheral denervation of cervical muscles was performed alone (3 patients) or in addition to DBS GPi (3 patients). Among non-primary dystonia, high DBS GPi efficacy was observed in patients with tardive dystonia. Mean improvement in motor BFMDRS was up to 90%. In BGC-associated dystonia, initial response to DBS GPi was good, however, deteriorated in the later time course. In the other neurodegenerative and acquired dystonia associated with structural brain lesions, functional outcome of DBS GPi was poor with minimal motor improvement. In patients with predominant dystonic tremor or myoclonus and distal limb dystonia, DBS of ventral lateral thalamic nuclei was preferred. Two patients with unilateral limb dystonia (incl. hemidystonia, action-specific/occupational dystonia) underwent unilateral Vopthalamotomy with good functional outcome. For dyskinetic CP patients, intrathecal baclofen pump therapy or selective combined (dorsal and ventral) rhizotomy was applied alone or in combination with stereotactic procedures (DBS or lesioning) and peripheral neurotomy. Conclusion: At present, DBS GPi has the largest evidence of efficacy and safety for dystonia. Selection of the other surgical approaches and targets is possible on the individual basis. Thalamic targets are to consider in tremulous/myoclonic dystonia or limb dystonia. There is still no clear evidence for DBS of subthalamic nucleus in dystonia. Stereotactic lesioning procedures have limited application and need to be performed unilaterally to avoid neurological complications. Surgical outcome in non-primary dystonia varies individually; in CP, often staged surgical procedures are needed. For maximal efficacy the timeliness of surgical intervention is important. Preoperative evaluation of surgical candidates should be carried on by experienced multidisciplinary team. [ABSTRACT FROM AUTHOR]

Background: Perivascular spaces (Virchow-Robin, PVS) are pial-lined slit-like spaces that surround perforating cerebral vessels. Small PVS (<2mm) can be detected in MRI in all ages. Enlarged PVS are considered a sign of normal brain aging and mostly asymptomatic. In patients with Parkinson's disease (PD), expanded PVS are often. Relationship between dilated PVS and PD is unclear; both alleviation and worsening of parkinsonian symptoms in contralateral extremities are described. Objective: To report a case of successful DBS in patient with cribrous STN. Methods: A 57-year-old woman had an 11-year history of PD. Motor symptoms manifested on the right side. Disabling pharmacoresistant motor fluctuations and dyskinesia appeared after 9 years and she was assigned for evaluation for PDsurgery. On admission, patient had bilateral akinetic-rigid syndrome with significant predominance in the right extremities, moderate postural instability, slight cranial and cervical dystonia. Levodopa-intake induced significant amelioration in hypokinesia and rigidity, improvement in balance and walking. Moderate dyskinesia was observed mainly in the right arm and leg. We used standard scales for clinical evaluation (UPDRS, PDQ-39, Schwab&England). Standard MRI revealed pronounced lacunar cysts in the left brain peduncle and striatum limiting stereotactic placement of DBS-electrode. Results: In order to assess DBS-suitability, comprehensive neuroimaging evaluation was performed. Direct visualization of basal ganglia was performed using 3T MRI and MR-tractography. Overextended PVS were detected in the left subthalamic nucleus and posterior subthalamic area. However, shape and size of cribrous STN were within normal range and internal capsule was not dislocated. Subsequently, DBS-electrodes were implanted in STN bilaterally using standard procedure. Position of the left STN-electrode was calculated by the anterolateral margin of PVS. Microelectrode recording performed during surgery showed no differences in neuronal electrical activity of the cribrous and normal STN. At three-month follow-up, UPDRSIII in off-medication state reduced by 79%, levodopa equivalent daily dose by 61%, PDQ39 by 35%. Motor fluctuations and dyskinesia improved significantly. Daily activity in off-state increased by 30%. Conclusion: Expanded PVS in midbrain and basal ganglia region may affect clinical manifestation of PD. Although, presence of cribrous changes do not hinder DBS or predict unfavorable outcome. [ABSTRACT FROM AUTHOR]

Cervical dystonia (CD) is the third most common movement disorder affecting 1 million people worldwide. Proprioceptive modulation is the hallmark of contemporary therapies for dystonia, but the mechanism for this intervention is unclear. We studied proprioceptive influence on CD by measuring the spontaneous single-neuron responses and local field potentials (LFP) from the globus pallidus interna (GPi) in 17 CD patients (9 isolated CD and 8 with CD as a feature of generalized dystonia). The goal was to examine how high-frequency neck vibration, a putative modulator of neck proprioception changes pallidal physiology. We found that the neck vibration instantaneously alters the pallidal single neuron activity. We also found that neck vibration modulates pallido-cerebellar connectivity by changing alpha band in LFP recordings. The effects were more robust in those with isolated CD. The vibration also affects pallido-hippocampal connectivity by modulating theta-band power. These effects were more robust in CD with generalized dystonia. Vibration changed LFP only in select pallidal regions. Regions where LFP power was substantially modulated had a prominent proportion of burst subtypes of neurons, compared to pause or tonic subtypes. Such disparity in subtype was absent in regions where the LFP power was not modulated or subtly reduced with neck vibration. When changes in the theta, alpha and beta bands of the LFP recordings were compared against each other in response to vibration, high correlation was observed.