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Biomedical subjects

R F Kaplan

Publications and source records attributed to R F Kaplan.

At least 37 records · Page 2Linked to original sources
PubMed1995

Mivacurium-induced neuromuscular blockade during sevoflurane and halothane anaesthesia in children.

The neuromuscular blocking effects of mivacurium during sevoflurane or halothane anaesthesia was studied in 38 paediatric patients aged 1-12 yr. All received premedication with midazolam, 0.5 mg.kg-1 po and an inhalational induction with up to 3 MAC of either agent in 70% N2O and O2. The ulnar nerve was stimulated at the wrist by a train-of-four stimulus every ten seconds and the force of adduction of the thumb recorded with a Myotrace force transducer. Anaesthesia was maintained with a one MAC end-tidal equivalent of either volatile agent for five minutes before patients received mivacurium (0.2 mg.kg-1) iv. The onset of maximal blockade occurred in 2.4 +/- 1.26 (mean +/- SD) min with halothane and 1.8 +/- 0.54 min with sevoflurane (NS). Four patients failed to achieve 100% block (3 halothane, 1 sevoflurane). The times from injection to 5, 75, and 95% recovery during sevoflurane (9.8 +/- 2.6, 19.5 +/- 4.4, and 24.2 +/- 4.8 min) were greater than during halothane anaesthesia (7.2 +/- 2.2, 15.0 +/- 4.0, 19.2 +/- 4.9 min, respectively (P < 0.005). All patients demonstrated complete spontaneous recovery of neuromuscular function (T1 > 95%, T4/T1 > 75%) during the surgery which lasted 24-63 min. All patients showed clinical signs of full recovery of neuromuscular blockade (i.e., headlift, gag, or cough). Pharmacological reversal was not required. It is concluded that following a single intubating dose of mivacurium, the time to maximum relaxation was not different during halothane and sevoflurane anaesthesia; recovery times to 5, 75 and 95% twitch height were longer during sevoflurane anaesthesia and neuromuscular reversal was not necessary.

Anesthesia Recovery Period↗
PubMed1995

Extinction during time controlled direct retinal stimulation after recovery from right hemispheric stroke.

The temporal variables of extinction in two patients with right hemispheric stroke and two normal controls were studied using a scanning laser ophthalmoscope (SLO). This instrument enabled eye movements to be controlled for by projecting time controlled stimuli directly on to the retina. Both patients had recovered from their stroke (four months and five years) and seemed clinically normal. At 50 ms, patient 1 extinguished one of two stimuli on seven of 40 double simultaneous stimulation (DSS) trials (five left, two right) and patient 2 extinguished the left stimulus on every DSS trial. At 100 ms, patient 1 performed almost perfectly, whereas patient 2 extinguished on 30% of the DSS trials (10 left, two right). At 200 ms, patient 2 performed perfectly. Neither of the controls showed extinction to DSS at any presentation time. Thus detecting DSS was time dependent in the patients but not the normal subjects. These data support the theory that recovery from neglect after right hemispheric damage may be mediated by the left hemisphere.

Adult↗
PubMed1994

The long-term clinical outcomes of Lyme disease. A population-based retrospective cohort study.

OBJECTIVE: To ascertain the prevalence of and risk factors for long-term sequelae from acute Lyme disease. DESIGN: Population-based, retrospective cohort study. SETTING: A coastal region endemic for Lyme disease. PARTICIPANTS: Patients with a history of Lyme disease who were previously treated with antibiotics were compared with randomly selected controls. MEASUREMENTS: A standardized physical examination, health status measure (Short Form 36), psychometric test battery, and serologic analysis. RESULTS: Compared with the control group (n = 43), the Lyme group (n = 38; mean duration from disease onset to study evaluation, 6.2 years) had more arthralgias (61% compared with 16%; P < 0.0001); distal paresthesias (16% compared with 2%; P = 0.03); concentration difficulties (16% compared with 2%; P = 0.03); and fatigue (26% compared with 9%; P = 0.04), and they had poorer global health status scores (P = 0.04). The Lyme group also had more abnormal joints (P = 0.02) and more verbal memory deficits (P = 0.01) than did the control group. Overall, 13 patients (34%; 95% CI, 19% to 49%) had long-term sequelae from Lyme disease (arthritis or recurrent arthralgias [n = 6], neurocognitive impairment [n = 4], and neuropathy or myelopathy [n = 3]). Compared with controls, patients who had long-term sequelae had higher IgG antibody titers to the spirochete (P = 0.03) and received treatment later (34.5 months compared with 2.7 months; P < 0.0001). CONCLUSIONS: Persons with a history of Lyme disease have more musculoskeletal impairment and a higher prevalence of verbal memory impairment when compared with those without a history of Lyme disease. Our findings suggest that disseminated Lyme disease may be associated with long-term morbidity.

Cohort Studies↗
PubMed1994

Dissociation of autonomic and subjective responses to emotional slides in right hemisphere damaged patients.

Autonomic and subjective responses to emotional and neutral slides were studied in patients with right hemisphere damage (RHD), left hemisphere damage (LHD) and normal controls (CON). Orienting and habituation to a series of pure tones (1000 Hz) were also examined. All subjects showed appropriate slide recognition and there were no group differences in subjective ratings. The CON group showed higher skin conductance responses (SCRs) to the emotional slides relative to the neutral slides, while the RHD group showed lower SCRs to both sets of slides. The LHD group showed higher SCRs independent of slide type. The results support the hypothesis (Heilman and Watson, Handbook of Neurology, Elsevier Science, 1989) that emotional paucity in RHD patients may be related to reduced autonomic arousal. However, there were no significant differences between groups in the orienting response or habituation to loud tones, suggesting that decreased arousal following RHD is not ubiquitous.

Arousal↗
PubMed1994

Habituation and sensitization of the orienting response following bilateral anterior cingulotomy.

Skin conductance response (SCR) was measured in an orienting response (OR) and habituation paradigm in 10 post-cingulotomy and age-matched control subjects. While both groups habituated, the cingulotomy patients exhibited a slower habituation rate, and greater variability across trials compared to controls. Habituation abnormalities were not associated with increased sensitization, as neither extended habituation training or dishabituation differentiated the groups. An increased frequency of spontaneous SCR activations occurred post-cingulotomy. The results suggest that the cingulate cortex influences the temporal stability of habituation. These findings are consistent with the subtle attentional dysfunction noted following cingulate damage.

Acoustic Stimulation↗
PubMed1994

A clinical grading scale to predict malignant hyperthermia susceptibility.

BACKGROUND: The diagnosis of an acute malignant hyperthermia reaction by clinical criteria can be difficult because of the nonspecific nature and variable incidence of many of the clinical signs and laboratory findings. Development of a standardized means for estimating the qualitative likelihood of malignant hyperthermia in a given patient without the use of specialized diagnostic testing would be useful for patient management and would promote research into improved means for diagnosing this disease. METHODS: Using the Delphi method and an international panel of 11 experts on malignant hyperthermia, a multifactor malignant hyperthermia clinical grading scale comprising standardized clinical diagnostic criteria was developed for classification of existing records and for application to new patients. RESULTS: This scale ranks the qualitative likelihood that an adverse anesthetic event represents malignant hyperthermia (malignant hyperthermia event rank) and that, with further investigation of family history, an individual patient will be diagnosed as malignant hyperthermia susceptible (malignant hyperthermia susceptibility rank). The assigned rank represents a lower bound on the likelihood of malignant hyperthermia. The clinical grading scale requires the anesthesiologist to judge whether specific clinical signs are appropriate for the patient's medical condition, anesthetic technique, and surgical procedure. CONCLUSIONS: The malignant hyperthermia clinical grading scale is recommended for use as an aid to the objective definition of this disease. It use may improve malignant hyperthermia research by allowing comparisons among well-defined groups of patients. This clinical grading system provides a new and comprehensive clinical case definition for the malignant hyperthermia syndrome.

Adult↗
PubMed1994

Jaw relaxation after a halothane/succinylcholine sequence in children.

BACKGROUND: Lack of complete jaw relaxation after a halothane-succinylcholine sequence has been described in the literature. To date, however, most existing studies are retrospective, and lack agreement on the magnitude and incidence of this phenomenon. This prospective study examined the incidence and degree of incomplete jaw relaxation in 500 children who were given intravenous succinylcholine during halothane anesthesia. METHODS: Five hundred consecutive unmedicated children received a minimum dose of 2 mg/kg intravenous succinylcholine after induction of anesthesia with halothane. The degree of jaw relaxation was assessed 45-60 s later by the same observer using a standardized clinical scale. The degree of relaxation was correlated with the type of surgical procedure, and the presence and intensity of fasciculations. RESULTS: Complete relaxation (mouth opened easily and fully) occurred in 95.4% of study patients. Incomplete relaxation (firm manual separation required to open the mouth fully) was seen in 4.4% of the patients. One child (0.2%) had masseter muscle rigidity (mouth could not be fully opened but intubation possible). There were no incidents of trismus (teeth clamped shut and intubation via direct visualization impossible). The incidence of incomplete relaxation and masseter muscle rigidity did not correlate with the presence or degree of fasciculations or the type of surgical procedure. There were no clinical signs of a hypermetabolic state or myoglobinuria in any patient. CONCLUSIONS: Incomplete jaw relaxation after a halothane-succinylcholine sequence is not uncommon in children, and is considered a normal response.

Anesthesia↗
PubMed1994

Serial assessment of acute stroke using the NIH Stroke Scale.

BACKGROUND AND PURPOSE: The National Institutes of Health (NIH) Stroke Scale has been used in clinical trials to assess neurological outcome after investigational therapy for acute stroke. We used the NIH Stroke Scale to study the degree and time course of recovery in patients with acute stroke who were treated with conventional therapy. METHODS: We serially assessed 50 patients with ischemic stroke who presented within 24 hours of onset of symptoms. Patients were grouped by stroke subtype. Major neurological improvement was defined as a decrease in the stroke score by 4 points or more. RESULTS: The mean NIH stroke score for all patients improved significantly by 7 to 10 days and at last follow-up (average, 44 days). Major neurological improvement was seen in 5 of 41 patients (12%; 95% confidence interval [CI], 2% to 22%) by 24 hours, 11 of 40 patients (28%; 95% CI, 14% to 41%) by 48 hours, and 19 of 37 patients (51%; 95% CI, 35% to 67%) by follow-up. The subgroup of patients with middle cerebral artery territory embolism showed a similar pattern of improvement; in contrast, patients with lacunar infarcts did not show significant change in scores during the study period. The score on admission did not correlate with the degree of subsequent improvement or deterioration. CONCLUSIONS: A significant percentage of patients with acute ischemic stroke treated with conventional therapy show early improvement as assessed by the NIH Stroke Scale. The degree and time course of recovery may be influenced by stroke type.

Acute Disease↗
PubMed1994

Lateralization of memory for the visual attributes of objects: evidence from the posterior cerebral artery amobarbital test.

We used the posterior cerebral artery amobarbital test to examine how each temporal lobe mediates memory for objects. Temporal lobectomy candidates were presented with four objects while one hemisphere was anesthetized. We assessed recall and recognition following recovery from the drug. Verbal recall was significantly better following object presentation to the left hemisphere when the left hemisphere was not the seizure focus. Recognition memory, tested with two identical objects, two objects that shared the same name but had different physical characteristics, and two foils, was superior following object presentation to the right hemisphere. Only the right hemisphere could discriminate identical objects from same-name foils. These data confirm that the left temporal lobe has an advantage in encoding the verbal representation of an object and suggest that the right temporal lobe is critical for memory of specific visual attributes of objects.

Adult↗
PubMed1992

Memory impairment and depression in patients with Lyme encephalopathy: comparison with fibromyalgia and nonpsychotically depressed patients.

Lyme encephalopathy, primarily manifested by disturbances in memory, mood, and sleep, is a common late neurologic manifestation of Lyme disease. We compared 20 patients with Lyme encephalopathy with 11 fibromyalgia patients and 11 nonpsychotically depressed patients using the California Verbal Learning Test, Wechsler Memory Scale, Rey-Osterrieth Complex Figure Test, Minnesota Multiphasic Personality Inventory (MMPI), and Beck Depression Inventory. Compared with patients with fibromyalgia or depression, the Lyme encephalopathy group showed mild, but statistically significant, memory deficits on two of the three memory tests. In contrast, the patients with fibromyalgia scored significantly higher than both other groups on the MMPI scale most sensitive to somatic concerns (scale 1), while the depressed patients scored higher than the Lyme patients on the scales most sensitive to depression (scale 2) and anxiety (scale 7). Physical complaints and depression were not major factors in memory performance among Lyme patients. These data support the hypothesis that Lyme encephalopathy is caused by CNS dysfunction and cannot be explained as a psychological response to chronic illness.

Adult↗
PubMed1991

Changing attentional demands in left hemispatial neglect.

Seven variations of a letter cancellation test were used to examine how varying attentional demands affect hemispatial neglect in patients with right hemisphere lesions. While the 14 targets always remained in the same location, the number of distractors (zero, nine, 28, or 82) as well as their complexity (one letter or nine different letters) were varied. The percentage of targets canceled in the left hemispace was linearly related to the number of distractors. There were no differences between the complexity conditions. In a second study, the same 14 targets were presented but the distractors (zero, 14, or 41) were all placed on the right. Increasing the number of distractors on the right increased neglect on both sides of the space. Taken together, these results suggest that, while the limited attentional resources of the left hemisphere are biased toward the right hemispace, the absence of contralateral attentional demands allows these resources to be directed ipsilaterally.

Aged↗
PubMed1990

Chronic neurologic manifestations of Lyme disease.

BACKGROUND AND METHODS: Lyme disease, caused by the tick-borne spirochete Borrelia burgdorferi, is associated with a wide variety of neurologic manifestations. To define further the chronic neurologic abnormalities of Lyme disease, we studied 27 patients (age range, 25 to 72 years) with previous signs of Lyme disease, current evidence of immunity to B. burgdorferi, and chronic neurologic symptoms with no other identifiable cause. Eight of the patients had been followed prospectively for 8 to 12 years after the onset of infection. RESULTS: Of the 27 patients, 24 (89 percent) had a mild encephalopathy that began 1 month to 14 years after the onset of the disease and was characterized by memory loss, mood changes, or sleep disturbance. Of the 24 patients, 14 had memory impairment on neuropsychological tests, and 18 had increased cerebrospinal fluid protein levels, evidence of intrathecal production of antibody to B. burgdorferi, or both. Nineteen of the 27 patients (70 percent) had polyneuropathy with radicular pain or distal paresthesias; all but two of these patients also had encephalopathy. In 16 patients electrophysiologic testing showed an axonal polyneuropathy. One patient had leukoencephalitis with asymmetric spastic diplegia, periventricular white-matter lesions, and intrathecal production of antibody to B. burgdorferi. Among the 27 patients, associated symptoms included fatigue (74 percent), headache (48 percent), arthritis (37 percent), and hearing loss (15 percent). At the time of examination, chronic neurologic abnormalities had been present from 3 months to 14 years, usually with little progression. Six months after a two-week course of intravenous ceftriaxone (2 g daily), 17 patients (63 percent) had improvement, 6 (22 percent) had improvement but then relapsed, and 4 (15 percent) had no change in their condition. CONCLUSIONS: Months to years after the initial infection with B. burgdorferi, patients with Lyme disease may have chronic encephalopathy, polyneuropathy, or less commonly, leukoencephalitis. These chronic neurologic abnormalities usually improve with antibiotic therapy.

Adult↗
PubMed1990

Prolonged neuromuscular blockade and ventilatory failure after renal transplantation and cyclosporine.

In a retrospective one-year study, we documented respiratory failure or prolonged neuromuscular blockade in eight of 65 patients with chronic renal failure who had received either vecuronium (four of 29 patients) or atracurium (four of 36 patients) during anaesthesia for kidney transplantation. We reviewed the charts of the patients and recorded all aspects of medication and anaesthesia to try to determine whether there might be a single factor associated with this high incidence (12 per cent) of respiratory failure. Anaesthesia for all patients was induced with thiopentone, isoflurane, and N2O/O2. Tracheal intubation was facilitated with muscle relaxants in a single bolus of vecuronium, 0.07 to 0.1 mg.kg-1, or atracurium, 0.3 to 0.5 mg.kg-1. Additional doses were given according to neuromuscular activity, which was monitored visually by response to train-of-four and tetanic stimulation. Anaesthesia was maintained with fentanyl/isoflurane and N2O/O2. After induction of anaesthesia, each patient received methylprednisolone, cefazolin, mannitol infusion for 24 hr beginning at the start of renal artery anatomosis, and either azathioprine (n = 57) or cyclosporine (n = 8). Relaxation was evaluated toward the end of the operation by train-of-four stimulation. Neuromuscular blockade was reversed with edrophonium (0.75-1 mg.kg-1) or neostigmine (0.06-0.08 mg.kg-1). The eight patients with prolonged neuromuscular blockade received ventilatory support for one to three hours after operation. Respiratory failure was significantly more frequent in patients who received cyclosporine (P less than 0.05).

Adult↗