Causes and prognosis of adults experiencing a first seizure in adulthood: A pilot cohort study conducted in five countries in Latin America.

There are limited data on first seizure (FS) among adults in low and middle-income countries. We describe findings from a prospective cohort study involving 180 adults presenting with seizures in emergency departments in five Latin American countries. Overall, 102 participants (56.7%) had acute symptomatic seizures (ASyS) while 78 (43.3%) had unprovoked seizures (UPS). Among patients with ASyS, 55 (53.9%) had structural causes, with stroke (n = 24, 23.5%), tumor (n = 10, 9.8%), and trauma (n = 3, 3%) being the most frequent. Nineteen patients (18.6%) had infectious causes, including four (4%) with meningoencephalitis, three (3%) neurocysticercosis, and two (2%) bacterial meningoencephalitis. Twenty patients (19.6%) had metabolic/toxic evidence, including four (4%) with uremic encephalopathy, two (2%) hyponatremia, and three (3%) acute alcohol intoxication. Immune dysfunction was present in seven (7%) patients and neurodegenerative in two (2%). Among participants with UPS, 45 (57.7%) had unknown etiology, 24 (30.7%) had evidence of structural disorders (remote symptomatic), four (5%) were related to infectious etiology (>7 days before the seizure), and five (6.4%) had genetic causes. During the 3- and 6-month follow-up, 29.8% and 14% of patients with UPS, respectively, experienced seizure recurrence, while 23.9% and 24.5% of patients with ASyS had seizure recurrence. Longer follow-up is necessary to assess seizure recurrence for patients with ASyS after the acute cause is resolved and to determine the 10-year risk of recurrence, which is part of the definition of epilepsy. PLAIN LANGUAGE SUMMARY: We monitored 180 adults who presented with their first seizure in emergency departments across five Latin American countries. Among these patients, 57% had acute symptomatic seizures, with structural causes such as stroke (23%), infection (17%), or tumor (10%) being more prevalent. Among the 43% with unprovoked seizures, 58% showed no identifiable acute cause, while 6.4% were due to genetics. Within 3 months after their initial seizure, 26.6% of individuals experienced a second seizure, with 11.9% continuing to have seizures in Months 3-6. Between Months 3 and 6, an additional 20% of patients encountered a second seizure. Research is needed to better understand the cause and prognosis of these patients to improve outcomes.

Environmental and occupational exposure to metals (manganese, mercury, iron) and Parkinson's disease in low and middle-income countries: a narrative review.

OBJECTIVES: We designed and conducted a narrative review consistent with the PRISMA guidelines (PROSPERO registration number: CRD42018099498) to evaluate the association between environmental metals (manganese, mercury, iron) and Parkinson's Disease (PD) in low and middle-income countries (LMIC). METHODS: Data sources: A total of 19 databases were screened, and 2,048 references were gathered. Study selection: Randomized controlled trials, cluster trials, cohort studies, case-control studies, nested case-control studies, ecological studies, cross-sectional studies, case series, and case reports carried out in human adults of LMIC, in which the association between at least one of these three metals and the primary outcome were reported. Data extraction: We extracted qualitative and quantitative data. The primary outcome was PD cases, defined by clinical criteria. A qualitative analysis was conducted. RESULTS: Fourteen observational studies fulfilled the selection criteria. Considerable variation was observed between these studies' methodologies for the measurement of metal exposure and outcome assessment. A fraction of studies suggested an association between the exposure and primary outcome; nevertheless, these findings should be weighted and appraised on the studies' design and its implementation limitations, flaws, and implications. CONCLUSIONS: Further research is required to confirm a potential risk of metal exposure and its relationship to PD. To our awareness, this is the first attempt to evaluate the association between environmental and occupational exposure to metals and PD in LMIC settings using the social determinants of health as a framework.

[Effect of muscle contraction on heart rate and skin blood flow. Preliminary results]. / Efecto de la contracción muscular en la frecuencia cardiaca y en el flujo sanguíneo cutáneo. Resultados preliminares.

Evaluation of heart rate variability is an important tool to study several diseases. The most important tests include the variability of the heart rate as a function of time and as function of frequency, variability of blood pressure and pulsatile cutaneous blood flow (PCBF). We studied the effect of a sustained contraction of the quadriceps muscle on the instantaneous heart rate and pulsatile cutaneous blood flow in 10 healthy subjects. We measured the R-R interval and the instantaneous heart rate, in the time domain, 10 beats before the contraction, the R-R interval that coincided with the onset of the contraction, and the 30 R-R intervals after the beginning of the contraction. To measure the PCBF we used a photopletismograph designed for this purpose. We recorded the surface electromyographic activity (EMG) of the quadriceps muscle to determine the onset and end of the muscle contraction, and measured respiratory movements with a belt. We found an increase of the instantaneous heart rate at the first and second beats after the onset of the contraction. There was a decrease of the pulsatile cutaneous blood flow of the finger pad immediately after the contraction, which lasted for approximately eight beats. The findings support the idea of a central command and co-activation of the motor and sympathetic nervous systems. This efferent sympathetic activity seems to act not just on the contracting muscle but also on the heart and the cutaneous blood vessels of the extremities. These findings imply that it is quite likely that the sympathetic efferent effect has a supraspinal origin. This is a test that could be used to study cardiovascular control by the sympathetic nervous system.

[Response of skin blood flow to several respiratory maneuvers in healthy subjects]. / Respuesta del flujo sanguíneo de la piel con diferentes maniobras respiratorias en sujetos sanos.

INTRODUCTION: In the diagnosis of autonomic disturbances, the variability of skin blood flow (SBF) and the sympathetic skin response (SSR) in response to several respiratory maneuvers are not routinely studied. OBJECTIVE: We sought to standardize the method of SBF variability and SSR in healthy subjects during four respiratory maneuvers: 1) spontaneous breathing (SB); 2) rhythmic breathing at a rate of 6 per minute (RB); 3) sudden deep inspiration (SDI); 4) Valsalva maneuver (VM). SUBJECTS, MATERIAL AND METHOD: We studied 30 healthy subjects with a mean age of 32 years, 60% were men and 40% women. We used a photopletysmograph in the finger pad to measure SBF and surface electrodes on the palms of the hand to register the SSR. We also recorded the ECG and the respiratory movements. The variables were: 1) amplitude of SBF; 2) latency and duration of SSR; 3) percentage of decrease of the SBF during the maneuvers compared with the basal flow. RESULTS: During spontaneous breathing there was no respiratory modulation of the SBF and during RB the SBF was modulated with respiration. With SDI there was a 60% decrease of the SBF. VM induced a larger SBF decrease of 72 per cent. A significant statistical difference was revealed when we compared the decrease of SBF basal breathing with SDI and VM (P < 0.001). The difference was also significant between the SDI and VM (P < 0.001). The SBF decrease recovered more slowly after the SDI (beat 7) than after the VM (veat 6). The SBF decrease was more pronounced in magnitude during the VM. The latency of the SSR appears spontaneously and at random in 57% of subjects during normal breathing but it appeared consistently during RB, SDI, and VM. The latency of SSR was longer during SB (1.7 +/- 0.7 s), RB (1.6 +/- 0.7 s) than SDI (0.7 +/- 0.5 s) and VM (0.8 +/- 0.9 s) (P > 0.050). Duration of the SSR was significantly longer in the SDI (around 7.8 +/- 2.4 s) and during the VM (8 +/- 2.5 s) as compared to normal breathing (6.3 +/- 1.0 s) and RB (6.4 +/- 1.5 s) (P < 0.009). CONCLUSIONS: SB and RB induce periodic modulation of sympathetic activity to skin blood vessels and sweat glands. SDI and VM produced a much greater activation of sympathetic skin activity than SB and RB. The increased SSR duration and the profound SBF decrease with SDI and VM as compared to SB or RB are consistent with this hypothesis. The latency of the SSR is much shorter with SDI and VM than with SB or RB. The most likely explanation is that the SSR, under these circumstances, results from a central command. The recovery to normal SBF is faster after the VM as compared to SDI. This suggests that the withdrawal of sympathetic responses is faster after the VM. The explanation for this is unknown but suggests that it might be baroreceptor mediated.

Efecto de la contracción muscular en la frecuencia cardiaca y en el flujo sanguÝneo cutßneo / Resultados preliminares. Effect of muscle contraction on heart rate and skin blood flow. Preliminary results

Evaluation of heart rate variability is an important tool to study several diseases. The most important tests include the variability of the heart rate as a function of time and as function of frequency, variability of blood pressure and pulsatile cutaneous blood flow (PCBF). We studied the effect of a sustained contraction of the quadriceps muscle on the instantaneous heart rate and pulsatile cutaneous blood flow in 10 healthy subjects. We measured the R-R interval and the instantaneous heart rate, in the time domain, 10 beats before the contraction, the R-R interval that coincided with the onset of the contraction, and the 30 R-R intervals after the beginning of the contraction. To measure the PCBF we used a photopletismograph designed for this purpose. We recorded the surface electromyographic activity (EMG) of the quadriceps muscle to determine the onset and end of the muscle contraction, and measured respiratory movements with a belt. We found an increase of the instantaneous heart rate at the first and second beats after the onset of the contraction. There was a decrease of the pulsatile cutaneous blood flow of the finger pad immediately after the contraction, which lasted for approximately eight beats. The findings support the idea of a central command and co-activation of the motor and sympathetic nervous systems. This efferent sympathetic activity seems to act not just on the contracting muscle but also on the heart and the cutaneous blood vessels of the extremities. These findings imply that it is quite likely that the sympathetic efferent effect has a supraspinal origin. This is a test that could be used to study cardiovascular control by the sympathetic nervous system.