The role of the homeobox transcription factor Pitx3 in the mesencephalic dopaminergic system

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal

Localisation Of The Subthalamic Nucleus In Parkinson’s Disease with Neural Beta and Gamma Activity of Local Field Potentials

Introduction: To refine the MRI-based target during DBS surgery, microelectrode recordings (MER) are often performed to detect target-specific single unit activity. This requires additional recording time and increases the risk for haemorrhage. In the future it may therefore be relevant to be able to determine the implantable lead's position based on local field potential (LFP) recordings from the lead itself which reflect activity of a larger neural population. This study aims to evaluate the nature of oscillatory activity in the subthalamic nucleus (STN) by means of intraoperative LFP-recordings, its relationship with microelectrode recordings and its potential use to locate the STN and its sensorimotor sub-area in patients with Parkinson’s disease during deep brain stimulation (DBS) surgery.Methods: 25 patients with Parkinson’s disease are included in this study. MER and LFPs are recorded every 0.5 mm from multiple microelectrodes during DBS surgery in 48 STNs. A novel optimization approach to map the measurement points on an atlas STN based on the MER properties is used to enable a detailed spatial representation of these points. Power and coherence in different LFP frequencies at all points are assessed in reference to the point's location inside or outside the STN and its sensorimotor sub-area.Results: Coherence between LFPs and the envelope of spiking activity significantly increases when entering the STN. There is also a pronounced increase in the LFP power in the gamma band, which persists throughout the entire STN in 100% of the cases. In 70% of the cases LFPs have a significantly higher power in the high beta frequency band in the sensorimotor STN, defined by the mapping algorithm, compared to the non-sensorimotor STN.Conclusions: LFP gamma oscillations provide a useful tool for locating the STN intraoperatively and LFP beta oscillations can become useful to discriminate the sensorimotor area within the STN

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

Decompressive hemicraniectomy in severe cerebral venous thrombosis: a prospective case series

Small retrospective case series suggest that decompressive hemicraniectomy can be life saving in patients with cerebral venous thrombosis (CVT) and impending brain herniation. Prospective studies of consecutive cases are lacking. Thus, a single centre, prospective study was performed. In 2006 we adapted our protocol for CVT treatment to perform acute decompressive hemicraniectomy in patients with impending herniation, in whom the prognosis with conservative treatment was considered infaust. We included all consecutive patients with CVT between 2006 and 2010 who underwent hemicraniectomy. Outcome was assessed at 12 months with the modified Rankin Scale (mRS). Ten patients (8 women) with a median age of 41 years (range 26–52 years) were included. Before surgery 5 patients had GCS < 9, 9 patients had normal pupils, 1 patient had a unilaterally fixed and dilated pupil. All patients except one had space-occupying intracranial hemorrhagic infarcts. The median preoperative midline shift was 9 mm (range 3–14 mm). Unilateral hemicraniectomy was performed in 9 patients and bilateral hemicraniectomy in one. Two patients died from progressive cerebral edema and expansion of the hemorrhagic infarcts. Five patients recovered without disability at 12 months (mRS 0–1). Two patients had some residual handicap (one minor, mRS 2; one moderate, mRS 3). One patient was severely handicapped (mRS 5). Our prospective data show that decompressive hemicraniectomy in the most severe cases of cerebral venous thrombosis was probably life saving in 8/10 patients, with a good clinical outcome in six. In 2 patients death was caused by enlarging hemorrhagic infarcts