Publications
Concept, neuroanatomy and surgical techniques
Functional stereotactic lesions in the central lateral nucleus of the medial thalamus have proved to be an effective treatment of neurogenic pain and other neurological disorders associated with thalamocortical dysrhythmia. The mechanisms underlying patient recovery after surgery are currently being explored using quantitative electroencephalography. Here we test the hypothesis that the particular role played by the non‐specific medial thalamic nuclei in thalamocortical dysrhythmia is based on the divergent connectivity between these non‐specific and reticular nuclei.
Functional neurosurgery relies on robust localization of the subcortical target structures, which cannot be visualized directly with current clinically available in-vivo imaging techniques. Therefore, one has still to rely on an indirect approach, by transferring detailed histological maps onto the patient's individual brain images.
During stereotactic functional neurosurgery, stimulation procedure to control for proper target localization provides a unique opportunity to investigate pathophysiological phenomena that cannot be addressed in experimental setups. Here we report on the distribution of response modalities to 487 intraoperative thalamic stimulations performed in 24 neurogenic pain (NP), 17 parkinsonian (PD) and 10 neuropsychiatric (Npsy) patients.
EEG techniques
We simultaneously recorded local field potentials (LFP) in the thalamus and EEG on the scalp of 17 patients suffering from neurogenic pain, epilepsy and movement disorders. The EEG of 11 patients displayed enhanced power in the theta frequency range (4–8Hz). The thalamic LFP of 14 patients peaked in the theta range. The theta coherence between EEG and LFP was significant for 12 patients and reached strengths up to 70%. These findings suggest that enhanced theta rhythmicity occurs in tight functional thalamocortical loops and is a major element in all three diseases investigated.
Investigation of sleep and sleep EEG before and after stereotactic neurosurgery.
The emergence of positive clinical symptoms is viewed as resulting from ectopic gamma-band activation, which we refer to as the "edge effect." This effect is observable as increased coherence between low- and high-frequency oscillations, probably resulting from inhibitory asymmetry between high- and low-frequency thalamocortical modules at the cortical level.
Epilepsy, Tinnitus and Neuropsychiatry
Essential Tremor
Neurogenic Pain
Patients with severe and chronic neurogenic pain are known to exhibit excess EEG oscillations in the 4- to 9-Hz theta frequency band in comparison with healthy controls. The generators of these excess EEG oscillations are localized in the cortical pain matrix. Since cortex and thalamus are tightly interconnected anatomically, we asked how thalamic activity and EEG are functionally related in these patients.
Das Buch spannt einen Bogen von den anatomischen und physiologischen Voraussetzungen der Schmerzempfindung über unterschiedliche medizinische Methoden der Schmerzbekämpfung bis zur gestalterischen Auseinandersetzung mit Schmerz in Literatur und Kunst.
This reference presents a new collection of diagrams of the human thalamus, basal ganglia, and adjoining structures for accurate targeting in stereotactic functional neurosurgery. This guide consists of a series of maps in the three stereotactic planes and comparisons between brains with similar and differing intercommissural distances to help specialists pinpoint precise targets, map through anatomic variations, and develop computerized models for stereotactic functional neurosurgery. Paired with a CD that allows for the enlargement and reader-friendly analysis of maps and illustrations found within the text, this source stands as the first atlas of the human thalamus and basal ganglia to focus on combined high stereotactic precision and anatomical resolution.
Parkinson
This reference presents a new collection of diagrams of the human thalamus, basal ganglia, and adjoining structures for accurate targeting in stereotactic functional neurosurgery. This guide consists of a series of maps in the three stereotactic planes and comparisons between brains with similar and differing intercommissural distances to help specialists pinpoint precise targets, map through anatomic variations, and develop computerized models for stereotactic functional neurosurgery. Paired with a CD that allows for the enlargement and reader-friendly analysis of maps and illustrations found within the text, this source stands as the first atlas of the human thalamus and basal ganglia to focus on combined high stereotactic precision and anatomical resolution.
According to the established pathophysiological concept of Parkinson's disease (PD), the loss of dopaminergic projections from the substantia nigra to the striatum leads to changes in basal ganglia activity (Lozano et al., 1998). The main output from the basal ganglia complex is via the pallido-thalamic tract to the thalamus.
The over-inhibition of thalamic relay cells by hyperactivity of the internal part of the globus pallidus is a cornerstone of the
parkinsonian pathophysiology that leads to a distortion of the thalamocortical dynamics called thalamocortical dysrhythmia
(TCD). Here, we present the results of the stereotactic pallidothalamic tractotomy (PTT), which interrupts selectively the
enhanced pallidal output to the thalamus in a restricted location in the fields of Forel.