MRI maps, segregation, and white matter connectivity of the human hypothalamus in health.

The human hypothalamus is composed of several gray matter territories, forming 10 different structures mainly referred to as nuclei: the preoptic, suprachiasmatic, supraoptic, infundibular, paraventricular, dorsomedial, ventromedial, posterior (dorsal; dorsal hypothalamic area), and tuberomamillary nuclei, and the lateral hypothalamic area. The macroconnectivity, described since the middle of the 19th century, is currently probed using MRI methods, notably those relying on diffusion techniques. The structural connections can be grouped as follows: connections with the olfactory system; stria terminalis connections; stria medullaris connections; ansa lenticularis connections; subthalamus connections; optic tract connections; intrahypothalamic connections; hypothalamo-hypophysis connections; hypothalamic commissures; cortex connections.

New insights into the functional significance of the frontal aslant tract: an anatomo-functional study using intraoperative electrical stimulations combined with diffusion tensor imaging-based fiber tracking.

We used the method of direct electrostimulation combined with navigated tractography to map the frontal "aslant" tract, enabling us to perform reliable anatomo-functional correlation in a patient undergoing awake surgery to remove a left frontal glioma. The findings enhanced our understanding of the organization of language within the human brain.

Neuromodulation for eating disorders: obesity and anorexia.

Extremes of eating disorders (ED) have become prevalent in both developed and developing countries. Available therapies, though largely effective, fail in a substantial number of patients and carry considerable side effects. Morbid obesity and anorexia nervosa (AN) represent important causes of morbidity and mortality among young adults. Morbid obesity affects disproportionate numbers of children. AN is also important for its high mortality in young adults. The challenges of effectively treating AN are well recognized. In this article, important aspects of ED are reviewed in detail and novel approaches to the treatment of ED are proposed.

Motor cortex stimulation does not improve dystonia secondary to a focal basal ganglia lesion.

OBJECTIVE: To assess the efficacy of epidural motor cortex stimulation (MCS) on dystonia, spasticity, pain, and quality of life in patients with dystonia secondary to a focal basal ganglia (BG) lesion. METHODS: In this double-blind, crossover, multicenter study, 5 patients with dystonia secondary to a focal BG lesion were included. Two quadripolar leads were implanted epidurally over the primary motor (M1) and premotor cortices, contralateral to the most dystonic side. The leads were placed parallel to the central sulcus. Only the posterior lead over M1 was activated in this study. The most lateral or medial contact of the lead (depending on whether the dystonia predominated in the upper or lower limb) was selected as the anode, and the other 3 as cathodes. One month postoperatively, patients were randomly assigned to on- or off-stimulation for 3 months each, with a 1-month washout between the 2 conditions. Voltage, frequency, and pulse width were fixed at 3.8 V, 40 Hz, and 60 µs, respectively. Evaluations of dystonia (Burke-Fahn-Marsden Scale), spasticity (Ashworth score), pain intensity (visual analog scale), and quality of life (36-Item Short Form Health Survey) were performed before surgery and after each period of stimulation. RESULTS: Burke-Fahn-Marsden Scale, Ashworth score, pain intensity, and quality of life were not statistically significantly modified by MCS. CONCLUSIONS: Bipolar epidural MCS failed to improve any clinical feature in dystonia secondary to a focal BG lesion. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that bipolar epidural MCS with the anode placed over the motor representation of the most affected limb failed to improve any clinical feature in dystonia secondary to a focal BG lesion.

Improved dexterity after chronic electrical stimulation of the motor cortex for central pain: a special relevance for thalamic syndrome.

OBJECTIVES: To demonstrate that motor cortex stimulation (MCS) could improve motor function in patients with neuropathic pain. METHODS: In this prospective clinical study of 38 patients referred for MCS as treatment for their neuropathic pain, we collected any declaration of improvement in motor performance that could be attributed to MCS. RESULTS: Ten patients (26%) declared a benefit in their motor function. Eight presented objective evidence of recovered dexterity for rapid alternating movements. A minor proportion had improvement in dystonic posture (n = 2), but none had detectable increased motor strength or tonus changes. Overall, 73% of the patients with limb ataxia declared a benefit after MCS. In 6 out of 10 patients (60%), the anatomic lesion responsible for pain was restricted to the lateral aspect of the thalamus. All of them had either clinical or electrophysiological evidence of lemniscal dysfunction (proprioceptive ataxia). No correlation was found between the scores of pain relief and the modification of motor status. The correlation between thalamic lesions and benefits in motor performance was significant (Fisher's exact test, two-tailed, p = 0.0017). CONCLUSIONS: Up to 26% of patients estimated that MCS improved their motor outcome through recovered dexterity and in cases of lateral thalamic lesions.

White matter connectivity of human hypothalamus.

The macroscopic extrinsic white matter connectivity and the internal structure of the hypothalamus are still incompletely defined in humans. We investigated whether in-vivo diffusion tensor imaging tractography provides evidence of systematization according to hypothalamic compartmentalization. Six defined hypothalamic macroscopic compartments, preoptic, supraoptic, anteroventral, anterodorsal, lateral and posterior, were probed, within the right and left hemispheres of 14 subjects. Important new insights into the macroscopic structure of hypothalamus and white matter connections were found; the preoptic, anteroventral, lateral and posterior compartments are strongly connected to the cortex. The anteroventral connects particularly to the prefrontal cortex while the preoptic compartment connects mainly to the deep anterior brain. The anterodorsal connects mainly to the medial thalamus and the midline gray matter. There is a rightward frontal trend of hemispheric connectivity for the preoptic, anteroventral and lateral compartments. These findings may aid new neuromodulation applications and understanding in brain connectomics.

Anatomy of the human thalamus based on spontaneous contrast and microscopic voxels in high-field magnetic resonance imaging.

BACKGROUND: Since the pioneering studies of human thalamic anatomy based on histology and binding techniques, little new work has been done to bring this knowledge into clinical practice. OBJECTIVE: With the advent of magnetic resonance imaging (MRI) we hypothesized that it was possible, in vitro, to make use of high spontaneous MRI contrasts between white and grey matter to directly identify the subcompartmentalisation of the thalamus. METHODS: An anatomic specimen was imaged at high field (4.7 T) (basal ganglia plus thalamus block; 3-dimensional (3D) T1-weighted spin echo sequence; matrix, 256 x 256 x 256; isotropic voxel, 0.250 mm/edge; total acquisition time, 14 hours 30 minutes). Nuclei were manually contoured on the basis of spontaneous contrasted structures; labeling relied on 3D identification from classic knowledge; stereotactic location of centers of nuclei was computed. RESULTS: Almost all intrathalamic substructures, nuclei, and white matter laminae were identified. Using 3D analysis, a simplified classification of intrathalamic nuclei into 9 groups was proposed, based on topographic MRI anatomy, designed for clinical practice: anterior (oral), posterior, dorsal, intermediate, ventral, medial, laminar, superficial, and related (epi and metathalamus). The overall 4.7-T anatomy matches that presented in the atlases of Schaltenbrand and Bailey (1959), Talairach et al (1957), and Morel et al (1997). CONCLUSION: It seems possible to identify the subcompartments of the thalamus by spontaneous MRI contrast, allowing a tissue architectural approach. In addition, the MRI tissue architecture matches the earlier subcompartmentalization based on cyto- and chemoarchitecture. This true 3D anatomic study of the thalamus may be useful in clinical neuroscience and neurosurgical applications.

Long-term follow-up of globus pallidus chronic stimulation in advanced Parkinson's disease.

To assess the long-term follow-up of the globus pallidus internus (GPi) stimulation, six patients were evaluated every year by using the Unified Parkinson's Disease Rating Scale (UPDRS). Three years postoperatively, GPi stimulation led to a significant improvement of dyskinesia severity (50%, P = 0.05) and activities of daily living (subscore of quality of life scale, 9%, P = 0.05). However, the improvement induced by chronic pallidal stimulation on the mean daily duration in the off state was lost at the last assessment.