PubMed · 7908096
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R Simons, J Krol. 1994-04-02. Visual loss from bungee jumping.. https://doi.org/10.1016/s0140-6736(94)92053-2
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BACKGROUND AND PURPOSE: Cerebral vasomotor reactivity can easily be assessed reliably by measuring vasodilatory response to acetazolamide by transcranial Doppler sonography. The aim of this study was to confirm the hypothesis that female sex is associated with an increased cerebrovascular flow reserve. METHODS: Blood flow velocity of the middle cerebral artery was measured by transcranial Doppler sonography in 36 healthy sex- and age-matched subjects. After the initial blood flow velocities were recorded, the subjects received 14.3 mg/kg body wt acetazolamide, ie, 1 g/70 kg, intravenously. The measurements were repeatedly performed at 5-minute intervals starting 10 minutes after injection and lasting for 30 minutes. The highest measured flow velocities were used for further analysis. RESULTS: In both groups mean blood flow velocity increased significantly after acetazolamide (women, from 60.2 +/- 12.5 to 89.9 +/- 14.4 cm/s, P < .006; men, from 54.5 +/- 18.8 to 75.7 +/- 24.5 cm/s, P < .02). The difference in mean blood flow velocity after acetazolamide between groups of women and men was statistically significant (P < .02). CONCLUSIONS: Female subjects show an increased vasodilatory response to the acetazolamide test compared with men.
In order to determine whether short and middle latency vestibular evoked potentials (VsEPs) can be recorded in humans in response to angular acceleration stimuli in the vertical plane, a drum, head-holder, and stepper motor were designed to deliver upward acceleration impulses of 10,000 degrees/s2 (1.8 degrees displacement) to the human head. Forehead and mastoid electrodes recorded electrical activity that was filtered, differentially amplified, and averaged in short (12.7 milliseconds) and middle (63.5 milliseconds) latency time frames. Control recordings were used to eliminate various types of artifact. Recordings were conducted in 7 normal subjects and in 4 control patients with congenital, profound hearing loss and absence of caloric responses. Short and middle latency VsEPs with high intrasubject and intersubject consistency were recorded in normal subjects and not in control patients. The middle latency responses were larger in amplitude than the short latency responses. The effects of stimulus intensity and repetition rate on VsEP waveform, latency, and amplitude studied. Experiments have shown that the responses are not electrical artifact, nor are they contaminated by auditory, somatosensory, or passive eye movement potentials.
OBJECTIVE: To determine whether children presenting with epidural hemorrhage (EDH) are as likely to have been abused as are children presenting with subdural hemorrhage (SDH). DESIGN: Retrospective chart review. SETTING: Level I regional trauma center and a regional children's hospital. PATIENTS: All children at both institutions 3 years old or younger with a diagnosis of EDH or SDH identified by a search of the computerized trauma registry and hospital medical records from 1985 through 1991. MEASUREMENT AND RESULTS: Complete records were found for 93 of 94 eligible subjects. The diagnosis of accidental or inflicted injury was ascertained from the patient's hospital medical record or the records of Child Protective Services. Of all subjects (n = 93), 52% (48/93) were male and the median age was 15 months. Abuse was diagnosed in 47% (28/59) of children with SDH and 6% (2/34) of those with EDH. Other significant injuries were found in 47% of children with SDH and 18% of children with EDH. There was no statistically significant difference between the two groups with respect to the likelihood of identifying a skull fracture, the need for surgical evacuation of the hemorrhage, or mortality. CONCLUSIONS: Our data are consistent with current biomechanical concepts of intracranial injury. EDHs results from brief linear contact forces that commonly occur in unintentional falls. SDHs are caused by global high-energy rotational acceleration/deceleration forces that are commonly generated in episodes of abuse. Compared with SDH, EDH rarely results from abuse.