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Biomedical subjects

F Velasco

Publications and source records attributed to F Velasco.

At least 163 records · Page 9Linked to original sources
PubMed1975

Specific and nonspecific multiple unit activities during the onset of pentylentetrazol seizures. I. Intact animals.

A quantitative evaluation of specific and nonspecific multiple unit activity (MUA) before and during pentylenetetrazol-induced EEG tonic-clonic discharges (OTCD) was made at four levels of the CNS: cortical, thalamic, mesencephalic, and pontine. In addition, MUA of sciatic nerve was recorded to detect possible spinal cord efferent discharges. At all levels, sustained increase in specific and nonspecific multiple unit activity preceded EEG and sciatic nerve discharges induced by pentylenetetrazol. Increments in nonspecific MUA occurred sooner and were larger than those of specific MUA, and increments in mesencephalic nonspecific MUA occurred sooner and were larger than those of other cortical, thalamic, and pontine nonspecific MUAs. This sequence of neuronal activation suggests that pentylenetetrazol seizures are initiated in nonspecific structures at the mesencephalic level.

Animals↗
PubMed1975

A statisticl outline of the subthalamic target for the arrest of tremor.

In 60 cases operated on for the treatment of tremor, the insertion of an electrode that measured 1 mm in diameter produced complete arrest (40 cases) or significant decrease (20 cases) of the tremor on the contralateral side. The area where such effect was obtained was studied in AP and lateral radiograms. Using a method of standardization of the size of the thalamus and subthalamus, based on a proportional reucction of the length of the AC-PC line, the cases were found to cover a small area in the subthalamus. A statistical analysis of the position of the electrode tips at the moment the tremor was arrested was carried out in order to determine, with a high degree of probability, the area that includes the mean value of the target for the general population. This work allowed us to outline a small zone in the subthalamus as the target to be destroyed in future cases. The practical implications of the method are discussed and the possibility of reducing the size of the lesion is pointed out.

Electrocoagulation↗
PubMed1975

[Effect of chlormandinone acetate upon seizures in epileptic children with latent signs of hyperandrogenism].

The effect of chlormadinone acetate (24 mg/day) upon the plasma levels of pituitary gonadotropins and gonadal hormones on the number of generalized convulsions and spike EEG density was investigated in a group of epileptic children with intractable seizures and with clinical signs suggestive of hyperandrogenism. In each case, the effect of chlormadinone was evaluated in relation to hormonal levels and seizures observed during a control period and under the effect of placebo as follows: Control (PC)-Chlormadinone acetate (PCL1)-Placebo (PP)-Chlormadinone acetate (PCL2). In a male child (4MS), the number of convulsive attacks observed in the control period (26/month) was reduced during PCL1 (2/month) increased during PP (12/month) and was reduced again during PCL2 (0/month). Spike EEG density showed a parallel course to the clinical attacks. In this case, control levels of testosterone were markedly elevated (40 ng/ml) and were decreased during PCL1 to 4.0 increased again during PP to 34.0 and decreased again during PCL2 to 1.2 ng/ml. Plasma levels of pituitary gonadotropins were unchanged throughout the entire period of study. In other cases, neither the number of epileptic attacks nor spike EEG density were apparently affected by this regime and plasma levels of pituitary gonadotropins and gonadal hormones were also unmodified. These results suggest that a latent state of hyperandrogenism may be detected in some epileptic patients with intractable seizures and that chlormadinone may reduce convulsive attacks in these patients, probably by decreasing testosterone plasma levels.

Androstenedione↗
PubMedDate not supplied

Absolute and relative predictor values of some non-invasive and invasive studies for the outcome of anterior temporal lobectomy.

BACKGROUND: There is controversy in the literature regarding the strategy used to obtain better outcomes after performing an anterior temporal lobectomy (ATL). Some investigators prefer to reduce the risks and costs of the predictor studies despite the fact that the number of patients cured after ATL (no seizures with no medication) is relatively small. Other investigators prefer to attempt a total cure in all patients by using all available predictor studies regardless of risks and costs. The latter strategy was the aim of the present work. METHODS: The absolute (%) and relative (ratio differences) predictor values of non-invasive and invasive studies for the outcome 24 months post-ATL were determined on 22 patients suffering from intractable non-lesional temporal lobe epilepsy. RESULTS: Under these conditions, 11 (50%) patients had excellent outcomes (seizure-free, no medication), 8 ( 36%), good outcomes (only auras with medication), and 3 (13.6%), poor ou tcomes (1 with >70%-seizure reduction and two no changes in seizure frequency). Predictors of excellent (vs. poor outcome) include the following: complex partial seizures (CXP) alone or associated with secondary generalized tonic-clonic seizures; ictal motionless stare and postictal amnesia; abnormal bitemporal spikes (prominent ipsilateral to ATL) and secondary bilateral synchrony EEG activities; focal hippocampal ictal EEG activities, and the presence of focal anterior temporal delta EEG activity 3 months after ATL. Predictors of poor (vs. excellent) outcomes include the following: CXP associated with other generalized seizure types; CTS, MRI, and EEG extratemporal abnormalities, and generalized basotemporal ictal EEG activities and the presence of seizures and focal anterior temporal spikes 3 months after ATL. CONCLUSIONS: The present study corroborates that no single predictive study (including non-invasive MRI and invasive ictal EEG activity) is predictive of the success or failure of ATL. Rather, a concordant combination of non-invasive and invasive studies is more likely to be predictive of a high probability of success. The high efficiency of ATL (86% of patients seizure-free) was accomplished by using all available predictor studies.

Electroencephalography↗
PubMedDate not supplied

Neuromodulation: an overview.

For over two centuries, electricity has been known to induce modification of neural and nerve fiber activity and has been proposed to be used to treat some neurological dysfunctions. The new era of the use of electrical current in the treatment of neurological symptoms began in 1967 with the use of totally implanted devices that deliver a controlled amount of electricity on a precise structure within the nervous systems and was first used to control pain. Extensive research has been carried out ever since to elucidate the mechanism of action of this treatment and extend its indication for the treatment of the other neurological symptoms. So far, there is evidence that the treatment is safe and efficient for long periods of time, as it does not induce permanent damage to the stimulated structure. Most likely, electrical current at the parameters used for therapeutic purpose induces an inhibition of the structure on which it is applied. However, this may be accompanied by either inhibition or excitation of anatomically related structures. For this reason, it seems more convenient to refer to this type of therapy as neuromodulation.A review of the historical development of this fascinating area is presented, with special attention to the evidence derived from experimental work on the parameters that electrical current must maintain to avoid damage to the underlying tissue.

Electric Stimulation Therapy↗