Assel Saryyeva

c-Fos expression after deep brain stimulation of the pedunculopontine tegmental nucleus in the rat 6-hydroxydopamine Parkinson model

Deep brain stimulation (DBS) is used to alleviate motor dysfunction in Parkinsons disease (PD). The pedunculopontine nucleus (PPN) may be a potential target for severe freezing and postural instability with 25 Hz stimulation being considered more effective than 130 Hz stimulation. Here we evaluated the expression of c-Fos after 25 Hz and 130 Hz DBS of the pedunculopontine tegmental nucleus (PPTg, i.e., the rodent equivalent to the human PPN) in the rat 6-hydroxydopamine (6-OHDA) PD model. Anaesthetized male Sprague Dawley rats with unilateral 6-OHDA-induced nigrostriatal lesions were stimulated with 25 Hz, 130 Hz, or 0 Hz sham-stimulation for 4h by electrodes implanted into the ipsilateral PPTg. Thereafter the distribution and number of neurons expressing the immediate early gene c-Fos, a marker for acute neuronal activity, was assessed. DBS of the PPTg induced strong ipsilateral c-Fos expression at the stimulation site, with 25 Hz having a more marked impact than 130 Hz. Additionally, c-Fos was strongly expressed in the central gray. In the dorsal part expression was stronger after 25 Hz stimulation, while in the medial and ventral part there was no difference between 25 Hz and 130 Hz stimulation. Expression in the basal ganglia was negligible. In the rat 6-OHDA PD model stimulation of the PPTg did not affect c-Fos expression in the basal ganglia, but had a strong impact on other functional circuitries. PPN stimulation in humans might therefore also have an impact on other systems than the motor system.

Cervical Myelopathy due to an Epidural Cervical Mass after Chronic Cervical Spinal Cord Stimulation

Background: Spinal cord stimulation (SCS) is an established treatment for neuropathic pain. Severe long-term complications are rare. Only recently secondary mass lesions associated with chronic stimulation were noted to occur. Objectives: To report the rare occurrence of cervical myelopathy secondary to an epidural cervical spinal mass after chronic cervical SCS. Methods: Implantation of a paddle electrode at C2-C4 for chronic neuropathic pain resulted in improvement of pain for several years but it lost its efficacy after 8 years. Myelography and postmyelographic CT detected an epidural mass surrounding the electrode and compressing the spinal cord when cervical myelopathy had developed 17 years after electrode implantation. Results: The mass which consisted of dense fibrous scar tissue was removed via hemilaminectomy. At postoperative follow-up at 8 months there was no further progression of gait disorder. Conclusion: Long-term cervical SCS in a rare case may lead to fibrous epidural mass lesions which may not only cause loss of efficacy but which may also result in new neurological deficits.

Human subthalamic nucleus – Automatic auditory change detection as a basis for action selection

The subthalamic nucleus (STN) shapes motor behavior and is important for the initiation and termination of movements. Here we ask whether the STN takes aggregated sensory information into account, in order to exert this function. To this end, local field potentials (LFP) were recorded in eight patients suffering from Parkinsons disease and receiving deep-brain stimulation of the STN bilaterally. Bipolar recordings were obtained postoperatively from the externalized electrode leads. Patients were passively exposed to trains of auditory stimuli containing global deviants, local deviants or combined global/local deviants. The surface event-related potentials of the Parkinsons patients as well as those of 19 age-matched healthy controls were characterized by a mismatch negativity (MMN) that was most pronounced for the global/local double deviants and less prominent for the other deviant conditions. The left and right STN LFPs similarly were modulated by stimulus deviance starting at about 100ms post-stimulus onset. The MMN has been viewed as an index of an automatic auditory change detection system, more recently phrased in terms of predictive coding theory, which prepares the organism for attention shifts and for action. The LFP-data from the STN clearly demonstrate that the STN receives information on stimulus deviance, possibly as a means to bias the system to interrupt ongoing and to allow alternative actions.

Reversal of Status Dystonicus after Relocation of Pallidal Electrodes in DYT6 Generalized Dystonia

Background DYT6 dystonia can have an unpredictable clinical course and the result of deep brain stimulation (DBS) of the internal part of the globus pallidus (GPi) is known to be less robust than in other forms of autosomal dominant dystonia. Patients who had previous stereotactic surgery with insufficient clinical benefit form a particular challenge with very limited other treatment options available. Case Report A pediatric DYT6 patient unexpectedly deteriorated to status dystonicus 1 year after GPi DBS implantation with good initial clinical response. After repositioning the DBS electrodes the status dystonicus resolved. Discussion This case study demonstrates that medication‐resistant status dystonicus in DYT6 dystonia can be reversed by relocation of pallidal electrodes. This case highlights that repositioning of DBS electrodes may be considered in patients with status dystonicus, especially when the electrode position is not optimal, even after an initial clinical response to DBS.

Pallidal and thalamic neural oscillatory patterns in tourette's syndrome: Pallido-Thalamic Activity in Tourette's Syndrome

Aberrant oscillatory activity has been hypothesized to play a role in the pathophysiology of Tourettes syndrome (TS). Deep brain stimulation (DBS) has recently been established as an effective treatment for severe TS. Modulation of symptom‐specific oscillations may underlie the mechanism of action of DBS and could be used for adaptive neuromodulation to improve therapeutic efficacy. The objective of this study was to demonstrate a pathophysiological association of pallidal and thalamic local field potentials (LFPs) with TS.

Sensory Alterations in Patients with Isolated Idiopathic Dystonia: An Exploratory Quantitative Sensory Testing Analysis

Abnormalities in the somatosensory system are increasingly being recognized in patients with dystonia. The aim of this study was to investigate whether sensory abnormalities are confined to the dystonic body segments or whether there is a wider involvement in patients with idiopathic dystonia. For this purpose, we recruited 20 patients, 8 had generalized, 5 had segmental dystonia with upper extremity involvement, and 7 had cervical dystonia. In total, there were 13 patients with upper extremity involvement. We used Quantitative Sensory Testing (QST) at the back of the hand in all patients and at the shoulder in patients with cervical dystonia. The main finding on the hand QST was impaired cold detection threshold (CDT), dynamic mechanical allodynia (DMA), and thermal sensory limen (TSL). The alterations were present on both hands, but more pronounced on the side more affected with dystonia. Patients with cervical dystonia showed a reduced CDT and hot detection threshold (HDT), enhanced TSL and DMA at the back of the hand, whereas the shoulder QST only revealed increased cold pain threshold and DMA. In summary, QST clearly shows distinct sensory abnormalities in patients with idiopathic dystonia, which may also manifest in body regions without evident dystonia. Further studies with larger groups of dystonia patients are needed to prove the consistency of these findings.

Bilateral Pallidal Stimulation Improves Chorea in Antiphospholipid Antibody Syndrome With Oral Anticoagulation

There are only few reports on DBS for chorea, almost all of which are related to Huntington’s disease, neuroacanthocytosis, or cerebral palsy. Chorea may also occur in antiphospholipid antibody syndrome (APLS), which is an adolescent-onset autoimmune disease associated with venous and arterial thromboses as well as miscarriages. Apart from movement disorders, patients with APLS often present with migraine and psychiatric symptoms. Thus far, no experience with DBS has been reported, which may either be owing to its often transient character or to concerns regarding the need for anticoagulation. Here, we report on the (long-term) efficacy and safety of DBS of the posteroventral lateral globus pallidus internus (GPi) in APLS.

Stereotactic Drainage of Empyema of the Cavum Septi Pellucidi et Vergae

Background: Persistent midline ventricular cavae may only rarely cause clinical symptoms. Exceptionally, empyemas may develop in these cavae. Optimal treatment has been defined only poorly so far. Methods: Here, we report successful treatment of a bacterial empyema in the cavum septi pellucidi et vergae due to sphenoid sinus sinusitis in a 36-year-old woman by stereotactic puncture and drainage of the empyema and long-term administration of antibiotics. Results and Conclusions: Stereotactic puncture and drainage accompanied by antibiotic therapy result in beneficial outcome in the long term. Transcallosal interhemispheric approaches and free-hand techniques should be discouraged since, according to previously published reports, they may result in severe morbidity or mortality in this condition.