Biomedical subjects

Clement Hamani

Publications and source records attributed to Clement Hamani.

22 records · Page 2Linked to original sources

PubMed2003

Longevity of batteries in internal pulse generators used for deep brain stimulation.

The longevity of batteries in internal pulse generators (IPGs) used clinically for deep brain stimulation is not known. We conducted a study to assess the life span of these batteries. From 1993 to 2000, 163 single-channel batteries were surgically implanted in our institution. The electrical settings utilized in patients who had battery failures were assessed and the total electrical energy delivered (TEED) was calculated and correlated with battery longevity. Fourteen IPGs had battery failure requiring replacement. The median life span of the batteries was 45 months. Batteries with high energy consumption as assessed by TEED had a reduced life span (r = -0.82, p < or = 0.001). Patients with essential tremor who required battery replacement needed higher settings to control their symptoms and therefore presented a shorter battery life when compared to patients with Parkinson's disease. In our series of patients who needed battery replacement, battery longevity varied with stimulation parameters but was longer than expected from the manufacturer's specifications.

Electric Power Supplies↗

PubMed2002

Inhibitory role of the zona incerta in the pilocarpine model of epilepsy.

Recent experiments have suggested that the zona incerta might be regarded as a highly sensitive structure for seizure induction. This sensitivity has been linked to this structure's abundant expression of cholinergic receptors. Here we have decided to investigate the participation of the GABAergic system of the zona incerta, one of its major neurotransmitters with widespread projections to the neocortex, in the pilocarpine (Pilo) model of epilepsy. Stereotaxic administration of a GABA(A) agonist (muscimol), antagonist (bicuculline) or saline (controls) bilaterally into the zona incerta of adult male Wistar rats was performed 30 min prior to the systemic injection of pilocarpine. Animals were electroencephalographically and behaviorally monitored for seizure activity. Administration of muscimol had a pro-convulsant effect characterised by a higher percentage of animals developing SE with a shorter latency. Conversely, administration of bicuculline had a dose dependent anticonvulsant effect, with no animals displaying SE. Our results contribute to the further characterisation of the regulatory role of the zona incerta in seizure-related phenomena, suggesting that its modulation might be a relevant target for anticonvulsant strategies.

Animals↗

PubMed2002

Spontaneous recurrent seizures and neuropathology in the chronic phase of the pilocarpine and picrotoxin model epilepsy.

In a recent publication, we have shown a potent interaction between the cholinergic and GABAergic systems in regard to seizure generation and developed the pilocarpine(pilo)/picrotoxin(PTX) model, in which combined injections of these agents have induced status epilepticus (SE) in rats. Here we report on the chronic features of this new animal model of epilepsy. Adult male Wistar rats were systemically injected with solutions containing 150/0.5 mg kg-1, 75/1.5 mg kg-1 and 50/2.0 mg kg-1 (pilo dose/PTX dose). Six epileptic and six control animals were observed for 120-131 days for the occurrence of spontaneous recurrent seizures (SRS). Electroencephalographic, neuropathologic and behavioral analyses were subsequently performed. Following SE, the animals went through a latent period and, subsequently, towards a state of 'chronic' epilepsy, characterized by the emergence of SRS. Animals that received 150/0.5 mg kg-1 presented a relatively short latent period, partial events as their most common initial seizure manifestations and a considerable subsequent progression towards generalization. The group injected with 75/1.5 mg kg-1 presented an extensive period during which the majority of the animals exclusively developed partial seizures (50 days). Animals injected with 50/2.0 mg kg-1 presented an average latent period of over 100 days. Only few animals within this group developed SRS. Our EEG, neuropathological and ictal behavioral findings, in conjunction with the fact that SE was required for the posterior development of SRS, suggest that our model parallels a human TLE condition. Even though diverse TLE models have been described, the pilo/PTX model has as a major feature the intriguing occurrence of disparities among these three groups in the chronic period, although no differences could be observed during SE induction. Future experiments conducted in this sense, might lead to important results in regard to the elucidation of mechanisms of epileptogenesis.

Acetylcholine↗

PubMedDate not supplied

The future of deep brain stimulation.

During the last year, there has been an increase in the number of applications of deep brain stimulation (DBS) for the treatment of several neurologic disorders. With a better understanding of the mechanisms of action of DBS, it is likely that improvement in the outcomes and an increase in the indications for these procedures will be possible. In fact, the knowledge gained with the applications of stimulation for movement disorders and pain has been leveraged toward the treatment of other disorders, including epilepsy and psychiatric conditions. This will act as a driving force to increase the efforts to improve the technology applied to design and manufacture new hardware.

Brain↗