In: Encyclopedic Reference of Pain, eds. R.F. Schmidt and W.D. Willis, 2006. Summary Neurophysiological studies at the cellular level (single unit activity and local field potentials or LFPs) as well as electroencephalographic (EEG) and magnetoencephalographic (MEG) recordings provide converging evidence for a thalamocortical dysregulation at the origin of chronic neurogenic pain of both peripheral and […]
To study the mechanisms of chronic neurogenic pain, we compared the power spectra of the resting EEG of patients (n = 15, 38-75 years, median 64 years, 6 women) and healthy controls (n = 15, 41-71 years, median 60 years, 8 women). On an average, the patient group exhibited higher spectral power over the frequency […]
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 […]
Neurophysiological studies at the cellular level (microelectrode unit activity recordings and local field potentials) as well as electro- and magnetoencephalographic recordings provide converging evidence for a thalamocortical dysregulation at the source of chronic neurogenic pain of both peripheral and central origin. These indicate an increase of low frequency thalamo-cortical rhythmicity originating in disfacilitation of thalamic […]
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 […]
Neuropsychiatric surgery has had a long and complex history with examples of less than optimal surgical procedures implemented in wrong settings. Such past errors have raised important philosophical and ethical issues that remain with us for good reasons. However, the existence of enormous suffering due to chronic therapy-resistant disabling neuropsychiatric disorders compels a search for […]
In: Surgical Management of Pain, chapter 63. Ed. K. Burchiel. Thieme New York, pp. 808-811, 2002 Read a part of the chapter on Google Books
Thalamic and cortical neurons are richly and reciprocally interconnected and support recurrent functional loops in the intact brain, but the role of this circuitry is still poorly understood. Here, we present evidence—from cellular and from functional neuroimaging in control and clinical domains—that thalamocortical resonance is not only a prerequisite for normal cognition, but that its […]
The companion paper (Llinás et al., 2001) presents evidence, at both cellular and network levels, for the role of resonant oscillatory thalamocortical properties in normal and pathological brain function. Here we present confirmatory single cell electrophysiology from the thalami of thalamocortical dysrhythmia (TCD) patients and review our surgical approach towards the relief of this chronic […]
Stereotactic neurosurgery aims at placing therapeutic lesions or chronic stimulating electrodes at very precise locations within the brain. Microelectrode recording and macrostimulation are used in addition to anatomoradiological techniques to optimize targeting. Recently, the usefulness of electrophysiological procedures has been questioned. Based on more than 500 therapeutic stereotactic lesions in the last 10 years at […]
Following earlie rstereotactic experiences, we re-explored the possibilities of a therapeutic lesion of the pallidothalamic tract in the fields H1 and H2 of Forel in patients with parkinsonian signs. The physiopathological rationale of the pallidothalamic tractotomy (PTT) is based on the presence in the parkinsonian brain of a state of thalamic overinhibition due to an […]
Reactualization of the medial thalamotomy, performed since the fifties in cases of neurogenic pain, has been guided by the discovery of low threshold calcium spikebursts at frequencies in the delta–theta range in the posterior part of the central lateral (CL) nucleus. This thalamic rhythmicity is transmitted to the cortex through thalamocortical resonant properties, giving rise […]