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Biomedical subjects

P R Yarnell

Publications and source records attributed to P R Yarnell.

At least 19 recordsLinked to original sources
PubMed1998

High-altitude cerebral edema evaluated with magnetic resonance imaging: clinical correlation and pathophysiology.

CONTEXT: Because of its onset in generally remote environments, high-altitude cerebral edema (HACE) has received little scientific attention. Understanding the pathophysiology might have implications for prevention and treatment of both this disorder and the much more common acute mountain sickness. OBJECTIVES: To identify a clinical imaging correlate for HACE and determine whether the edema is primarily vasogenic or cytotoxic. DESIGN: Case-comparison study. SETTING: Community hospitals accessed by helicopter from mountains in Colorado and Alaska. PATIENTS: A consecutive sample of 9 men with HACE, between 18 and 35 years old, 8 of whom also had pulmonary edema, were studied after evacuation from high-altitude locations; 5 were mountain climbers and 4 were skiers. The control group, matched for age, sex, and altitude exposure, consisted of 3 subjects with high-altitude pulmonary edema only and 3 who had been entirely well at altitude. Four patients with HACE were available for follow-up imaging after complete recovery. MAIN OUTCOME MEASURES: Magnetic resonance imaging (MRI) of the brain during acute, convalescent, and recovered phases of HACE, and once in controls, immediately after altitude exposure. RESULTS: Seven of the 9 patients with HACE showed intense T2 signal in white matter areas, especially the splenium of the corpus callosum, and no gray matter abnormalities. Control subjects demonstrated no such abnormalities. All patients completely recovered; in the 4 available for follow-up MRI, the changes had resolved entirely. CONCLUSIONS: We conclude that HACE is characterized on MRI by reversible white matter edema, with a predilection for the splenium of the corpus callosum. This finding provides a clinical imaging correlate useful for diagnosis. It also suggests that the predominant mechanism is vasogenic (movement of fluid and protein out of the vascular compartment) and, thus, that the blood-brain barrier may be important in HACE.

Adult↗
PubMed1998

Lightning injuries during snowy conditions.

Skiers and other snow sports enthusiasts can become lightning casualties. Two such accidents are reported, one being fatal. There are fewer warning signals of impending lightning strikes in winter-like conditions. However, outdoor activists should be aware of at least two suspicious clues: the appearance of convective clouds, and the presence of graupel (snow pellets) during precipitation.

Adult↗
PubMed1997

A bolt from the blue: lightning strike to the head.

We report an extraordinary event of a lightning strike to the head of a helmeted bicyclist that occurred under fair weather conditions with a cloudless sky. The patient sustained a cardiac arrest and hypoxic encephalopathy with residual neurologic impairment. With the availability of highly developed meteorologic equipment, we were able to determine that the lightning "bolt from the blue" probably originated in a thunderstorm that was about 16 km away and obscured by the mountains.

Brain Injuries↗
PubMed1995

Neurorehabilitation of lightning and electrical injuries.

Lightning and electrical (L/E) injuries can be among the most dramatic of all events that damage the nervous system. The three major classes of neurologic sequelae that require the expertise of the neurorehabilitationist are: (1) cerebral disorders, either global or focal; (2) neuropsychologic sequelae; and (3) spinal cord injury. Neurorehabilitation management necessary for each of these three areas will be discussed. From the viewpoint of the neurorehabilitationist, therapy principles are the same for L/E trauma as for other more common forms of injury. The goal is to maximize the functional return given the specific impairment.

Brain Injuries↗
PubMed1995

Neurologic complications of lightning injuries.

Over the past ten years, we have cared for 13 patients who suffered serious neurologic complications after being struck by lightning. The spectrum of neurologic lesions includes the entire neuraxis from the cerebral hemispheres to the peripheral nerves. We describe these various neurologic disorders with regard to the site of the lesion, severity of the deficit, and the outcome. Damage to the nervous system can be a serious problem for patients struck by lightning. Fatalities are associated with hypoxic encephalopathy in patients who suffered cardiac arrests. Patients with spinal cord lesions are likely to have permanent sequelae and paralysis. New technology for detecting lightning with wideband magnetic direction finders is useful in establishing lightning-flash densities in each state. Florida and the Gulf Coast states have the highest densities. Colorado and the Rocky Mountain states have the next highest.

Adolescent↗
PubMed1980

Long-term survival and neurologic status after resuscitation from out-of-hospital cardiac arrest.

Thirty-eight survivors from among 117 patients hospitalized after out-of-hospital cardiac arrest were evaluated approximately 3 1/2 years later. Twenty patients were living; 18 had died. Fifty-three percent had resumed independent social activities, but only 32% had returned to work. Eight of 14 patients tested were normal on limited neuropsychologic tests. Satisfactory long-term outcome was associated statistically with the patient's being awake on admission or awakening to follow simple commands within 2 days, and with good neurologic status at the time of discharge from the hospital. None of nine patients with poor neurologic function at discharge subsequently resumed working or independent living.

Follow-Up Studies↗
PubMed1979

Quality of survival after out-of-hospital cardiac arrest: predictive value of early neurologic evaluation.

One hundred and seventeen patients were admitted following out-of-hospital cardiac arrest. After initial neurologic evaluation, they were followed prospectively until discharge or death. Seventeen patients were alert when admitted. Of these, four died and 10 of 13 survivors were neurologically normal. One hundred of the patients were unresponsive; of these, 60 died. Of 40 survivors, 15 were neurologically normal, at discharge; 15 could perform some self-care but were confused, and 10 required total care. Absence of pupillary light reaction, oculocephalic reflexes, purposeful response to pain, and spontaneous respirations were associated with high mortality and more severe neurologic deficits. However, some patients with usually unfavorable signs recovered good neurologic function.

Aged↗
PubMed1977

Origin of seizures in elderly patients.

Among 50 previously well patients, aged 69 years or older, who had a first seizure, a cause could be identified in only 25 (50%). Cerebrovascular disease accounted for the seizures in 30% of the total group. Only one tumor was found. Treatable causes were found in 20%. In 25 patients (50%), a cause could not be identified. A total of 56% of the patients had focal motor seizures, and in 44%, the seizures were generalized. A definite cause could be established in 57% of those with focal seizure and in 41% of those with generalized seizures. These results are compared with previous surveys of adult-onset epilepsy and indicate a somewhat different etiologic distribution in elderly patients.

Age Factors↗
PubMed1977

Cortical deafness: demonstration of the pathologic anatomy by CT scan.

A 27-year-old man with a prosthetic mitral valve had bilateral cerebral infarcts that caused a nonfluent aphasia, oral apraxia, and deafness. A computer-assisted tomographic scan showed symmetrical bilateral temporoparietal lesions. A review of the literature on other cases of cortical auditory deficits suggests that the clinical syndrome of pure word deafness in many cases is probably a less severe form of cortical deafness and is due to less extensive bilateral temporal gray matter lesions. However, strictly white matter lesions may produce some cases of either syndrome.

Adult↗
PubMed1977

Hyponatremia and central pontine myelinolysis.

Autopsy in a patient with severe hyponatremia showed central pontine myelinolysis. Review of our patients with central pontine myelinolysis and those described in the English literature to data disclosed that 61 percent had documented hyponatremia. While the exact mechanism involving hyponatremia and central pontine myelinolysis cannot be defined, a circumstantial relationship is apparent. The purpose of this paper is to emphasize this relationship and to suggest that the possibility of central pontine myelinolysis be considered in any patient with hyponatremia and neurologic dysfunction.

Alcoholism↗
PubMed1976

Seizure admissions to a city hospital: the role of alcohol.

Among 472 adult seizure admissions to a municipal hospital, 41% had a history of alcohol abuse. Those were predominantly men aged 40 to 50 years. The primary underlying conditions were the alcohol withdrawal state (59%) and posttraumatic seizures. The nonalcohol groups included men and women equally, commonly between 20 and 40 years old, and frequent causes were vascular disease and posttraumatic seizures. However, many patients (24% in the alcohol and 39% in the nonalcohol groups) had no demonstrable cause. Focal sizures comprised 24% of the alcohol and 20% of the nonalcohol groups. Nonalcoholic focal seizures had a tumor or vascular lesion in 47%; above age 50 the association was 60%. Alcohol-related focal seizures had such a lesion in 15%, and only 19% above age 50. Conditions associated with alcoholic focal seizures were alcohol withdrawal and posttrauma sequelae.

Adult↗
PubMed1976

Alcoholic cerebellar disease and seizures.

Forty-eight chronic alcoholic patients with a clinical picture consistent with midline cerebellar disease were evaluated regarding alcohol related seizures. These seizures were noted in about 15% of this patient group. This seizure incidence approximates that in the severely alcoholic hospitalized population. Thus, the midline cerebellar degeneration does not appear to influence the seizure diathesis in the chronic alcoholic.

Adult↗
PubMed1975

Focal seizures and aminophylline.

Intravenous aminophylline therapy for acute exacerbation of chronic obstructive pulmonary disease may trigger prolonged and difficult to control focal motor seizures with generalization. This can occur in previously neurologically asymptomatic patients and be associated with a poor outcome. Most patients exhibited periodic lateralized epileptiform discharges or had autopsy-proved focal central nervous system lesions, or both. If focal and generalized seizures develop during aminophylline therapy, drug toxicity should be suspect as announcing a focal central lesion. Careful individual monitoring of aminophylline dose and administration rate is essential.

Aged↗