Anodal tDCS Combined With Radial Nerve Stimulation Promotes Hand Motor Recovery in the Acute Phase After Ischemic Stroke.

BACKGROUND AND OBJECTIVE: The question of the best therapeutic window in which noninvasive brain stimulation (NIBS) could potentiate the plastic changes for motor recovery after a stroke is still unresolved. Most of the previous NIBS studies included patients in the chronic phase of recovery and very few in the subacute or acute phase. We investigated the effect of transcranial direct current stimulation (tDCS) combined with repetitive peripheral nerve stimulation (rPNS) on the time course of motor recovery in the acute phase after a stroke. METHODS: Twenty patients enrolled within the first few days after a stroke were randomized in 2 parallel groups: one receiving 5 consecutive daily sessions of anodal tDCS over the ipsilesional motor cortex in association with rPNS and the other receiving the same rPNS combined with sham tDCS. Motor performance (primary endpoint: Jebsen and Taylor Hand Function Test [JHFT]) and transcranial magnetic stimulation cortical excitability measures were obtained at baseline (D1), at the end of the treatment (D5), and at 2 and 4 weeks' follow-up (D15 and D30). RESULTS: The time course of motor recovery of the 2 groups of patients was different and positively influenced by the intervention (Group × Time interaction P = .01). The amount of improvement on the JHFT was greater at D15 and D30 in the anodal tDCS group than in the sham group. CONCLUSION: These results show that early cortical neuromodulation with anodal tDCS combined with rPNS can promote motor hand recovery and that the benefit is still present 1 month after the stroke.

Transition from rest to movement: brain correlates revealed by functional connectivity.

It is suggested that resting state networks reflecting correlated neural regional activities participate significantly in brain functioning. A fundamental issue is to understand how these networks interact and how their activities change during behavioral transitions. Our aim was to understand better with functional MRI connectivity how the brain switched from a "resting" to a movement-related state by exploring the transitory readiness state for an intended movement of the right hand. Our study does not address movement preparation occurring in a time scale of milliseconds before movement which has been widely studied but movement-readiness which can last longer. At rest, in the absence of overt goal-directed behavior, a "default-mode" network, whose main areas are the posterior cingulate cortex and precuneus (PCC/Pcu), shows high activity interpreted as day dreaming, free association, stream of consciousness, and inner rehearsal. We found that, during rest, the "default-mode" network and the sensorimotor network were not functionally correlated. During movement-readiness, the two networks were functionally correlated through an interaction between the PCC/Pcu and the medial superior parietal cortex in the upper precuneus. The complex PCC/Pcu has been shown to be involved in retrieval and/or setting up spatial attributes for motor imagery, and thus, would be a key region in the movement-readiness phase. It might functionally connect to the medial superior parietal cortex to initiate the movement programming through retrieval of suited movement parameters. The anterior cingulum, functionally correlated to the primary sensorimotor cortex during movement-readiness would have a motivational role or could generate predictions about the movement.

Induction of cortical plastic changes in wrist muscles by paired associative stimulation in the recovery phase of stroke patients.

BACKGROUND: Paired associative stimulation (PAS) combining peripheral nerve and transcranial magnetic stimulation (TMS) have been proposed to induce long-term changes in excitability of the cerebral cortex and potentially optimize motor recovery in stroke patients. OBJECTIVE: This pilot study examined whether short-lasting changes in cortical excitability could be induced by a single session of PAS within the first months after stroke. METHODS: Six hemiparetic patients with a subcortical stroke were included. The single session PAS protocol was applied at 1, 5, and 12 months after stroke. During the follow-up, the clinical recovery of wrist function was assessed in parallel to the PAS study by the Fugl-Meyer motor scale and dynamometry of wrist extension. RESULTS: The PAS protocol induced a significant extensor carpi radialis motor evoked potential facilitation (mean +78.5%) on the paretic side 5 months after stroke. The facilitation was still present 12 months after stroke but on average smaller (+30 %). CONCLUSIONS: These electrophysiological findings suggest that patients with subcortical infarcts may respond to PAS in an earlier than later period after stroke. If the clinical efficacy of interventions such as PAS is confirmed, it could be proposed early as add-on therapy to optimize training-induced plasticity processes.

Hypothalamic activation in spontaneous migraine attacks.

BACKGROUND: Migraine sufferers experience premonitory symptoms which suggest that primary hypothalamic dysfunction is a likely trigger of the attacks. Neuroendocrine and laboratory data also support this hypothesis. To date, positron emission tomography (PET) scans of migraine sufferers have demonstrated activation of brainstem nuclei, but not of the hypothalamus. OBJECTIVE: To record cerebral activations withH2 15OPET during spontaneous migraine without aura attacks. METHODS: We scanned 7 patients with migraine without aura (6 females and 1 male) in each of 3 situations: within 4 hours of headache onset, after headache relief by sumatriptan injection (between the fourth and the sixth hour after headache onset), and during an attack-free period. RESULTS: During the headache we found not only significant activations in the midbrain and pons, but also in the hypothalamus, all persisting after headache relief by sumatriptan. CONCLUSION: Hypothalamic activity, long suspected by clinical and experimental arguments as a possible trigger for migraine, is demonstrated for the first time during spontaneous attacks.

Writing, calculating, and finger recognition in the region of the angular gyrus: a cortical stimulation study of Gerstmann syndrome.

OBJECT: In an attempt to gain a better understanding of the cerebral functions represented in the angular gyrus and to spare them during surgery, the authors studied patients with brain tumors located close to the angular gyrus and mapped cortical sites by using electrostimulation. METHODS: Before undergoing tumor removal, six right-handed patients (five with left and one with right hemisphere tumors) were studied using cortical mapping with the aid of calculating, writing, finger-recognition, and color-naming tasks in addition to standard reading and object-naming tasks (for a total of 36 brain mapping studies). Strict conditions of functional site validation were applied to include only those cortical sites that produced repetitive interferences in the function tested. Preoperatively, four of the patients exhibited discrete symptoms related to Gerstmann syndrome while performing very specific tasks, whereas the other two patients presented with no symptoms of the syndrome. No patient had significant language or apraxic deficits. Distinct or shared cortical sites producing interferences in calculating, finger recognition, and writing were repeatedly found in the angular gyrus. Object- or color-naming sites and reading-interference sites were also found in or close to the angular gyrus; although frequently demonstrated, these latter results were variable and unpredictable in the group of patients studied. Finger agnosia and acalculia sites were also found elsewhere, such as in the supramarginal gyrus or close to the intraparietal sulcus. Mechanisms involved in acalculia, agraphia, or finger agnosia (either complete interferences or hesitations) during stimulation were various, from an aphasia-like form (for instance, the patient did not understand the numbers or words given for calculating or writing tasks) to an apparently pure interference in the function tested (patients understood the numbers, but were unable to perform a simple addition). CONCLUSIONS: Symptoms of Gerstmann syndrome can be found during direct brain mapping in the angular gyrus region. In this series of patients, sites producing interferences in writing, calculating, and finger recognition were demonstrated in the angular gyrus, which may or may not have been associated with object-naming, color-naming, or reading sites.