Acute and Evolving MRI of High-Altitude Cerebral Edema: Microbleeds, Edema, and Pathophysiology.

MR imaging of high-altitude cerebral edema shows reversible WM edema, especially in the corpus callosum and subcortical WM. Recent studies have revealed hemosiderin deposition in WM long after high-altitude cerebral edema has resolved, providing a high-altitude cerebral edema "footprint." We wished to determine whether these microbleeds are present acutely and also describe the evolution of all MR imaging findings. In 8 patients with severe high-altitude cerebral edema, we obtained 26 studies: 18 with 3T and 8 with 1.5T scanners, during the acute stage, recovery, and follow-up in 7 patients and acutely in 1 patient. Imaging confirmed reversible cytotoxic and vasogenic WM edema that unexpectedly worsened the first week during clinical improvement before resolving. The 3T SWI, but not 1.5T imaging, showed extensive microbleeds extending beyond areas of edema seen acutely, which persisted and with time coalesced. These findings support cytotoxic and vasogenic edema leading to capillary failure/leakage in the pathophysiology of high-altitude cerebral edema and provide imaging correlation to the clinical course.

Mountain medical mystery. Unwitnessed death of a healthy young man, caused by lightning.

A healthy 20-year-old man failed to return home after a jog in the Colorado mountains. His lifeless body was found the next day on an exposed mountain slope. The differential diagnosis in such mysterious, unwitnessed mountain deaths includes cardiac arrhythmia, cerebral hemorrhage, pulmonary embolism, seizures, trauma, high-altitude sickness, and hypothermia. The cause of death in this case was established on postmortem examination. The findings of ruptured tympanic membranes and a melted shoe established this as a case of lightning strike fatality. The National Lightning Detection Network can be a valuable resource to investigators by providing information on the location and date of lightning strikes in the vicinity of the victim.

High-altitude cerebral edema (HACE): the Denver/Front Range experience.

High-altitude cerebral edema (HACE) is a potentially fatal metabolic encephalopathy associated with a time-dependent exposure to the hypobaric hypoxia of altitude. Symptoms commonly are headache, ataxia, and confusion progressing to stupor and coma. HACE is often preceded by symptoms of acute mountain sickness and coupled, in its severe form, with high-altitude pulmonary edema. Although HACE is mostly seen at altitudes above that of the Denver/Front Range visitor-skier locations, we report our observations over a 13-year period of skier-visitor HACE patients. It is believed that this is a form of vasogenic edema, and it is responsive to expeditious treatment with a successful outcome.

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.

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.

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.

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.

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.

Childhood lightning injuries on the playing field.

Two young boys were struck by lightning during summer outdoor activities. One of them died. A literature review reveals that the most commonly reported locations of childhood lightning injuries are on the playing field, at the swimming pool, and in tents. Knowledge of measures to lower the risks of lightning strikes as well as the use of new lightning detection technology should help to reduce the numbers of these tragic events in the future.

Minor whiplash head injury with major debilitation.

A group of patients suffering major debility after minor whiplash head trauma, seen in one office practice, has been retrospectively studied. Typically, acute neck and upper back aches and headache evolved into a multiple somatic, affective and cognitive dysfunction syndrome. Neuropsychological evaluations noted impairments on tests of cognitive flexibility, non-verbal reasoning, new learning/memory, psychomotor agility, and attention. However, in the subacute period, neurological examination, imaging and clinical electrophysiological studies were unable to localize, structurally or functionally, the source of the above dysfunctions.

Basilar artery narrowing and hyperparathyroidism: illustrative case.

A patient presenting with a pontine infarction caused by mid-basilar artery narrowing associated with hyperparathyroidism is described. The narrowing reversed with surgical removal of his parathyroid adenoma and normalization of his serum calcium. This patient's illness lends evidence to the role of calcium in cerebral vasoconstriction.

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.

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.

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.

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.