This study was designed to evaluate the functional response of the median nerve at the wrist to various degrees of acute, local compression in hypertensive patients. After measuring resting tissue fluid pressure in the carpal tunnel of the nondominant hand of nine subjects (diastolic pressures of 90 mm Hg or greater), localized pressures of 50, 60, or 70 mm Hg were applied to the palmar aspect of the wrist. Motor and sensory latencies and amplitudes of the median nerve were evaluated before compression, during 30-240 min of compression, and during the postcompression recovery phase. Sensory responses were completely blocked at a threshold tissue fluid pressure of 60-70 mm Hg, measured by the wick catheter technique. This pressure threshold was greater than the 40-50 mm Hg previously found in normotensive subjects. The tissue pressure threshold of normotensive and hypertensive subjects was consistently 30 mm Hg below diastolic blood pressure (approximately 45 mm Hg below mean arterial blood pressure). These results support the concept that ischemia is the prime mechanism of conduction block in low pressure, nerve-compression syndromes.
The investigation of Structure 10L-26 has revealed a series of sequent monumental constructions underlying the elaborate final phase temple/pyramid made famous by the Maya area's largest hieroglyphic stairway. The meticulous recording and analysis of the archaeological, architectural, hieroglyphic, and iconographic materials from this sequence of sculpture-adorned buildings provides the opportunity for a diachronic view of the nature of the historical record and political symbolism. Investigations conducted to date provide hieroglyphic and archaeological evidence in support of the sequence of rulers documented in the official histories of the last four rulers of Copan, and evidence of a dramatic shift in the use of this space, and of political symbolism in general, by the fifteenth king, Smoke Shell. While the lack of evidence for “re-writing of history” will be encouraging to many, the evidence also shows the need for a careful assessment of official histories by archaeological excavations. Just as important, the Copan Acropolis research demonstrates the usefulness of incorporating ideas and data derived from the careful scrutiny of the public monuments in ongoing archaeological investigations and model building.
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