Journal of neurosurgery
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Journal of neurosurgery · Nov 1996
Monitoring of cerebral oxygenation in patients with severe head injuries: brain tissue PO2 versus jugular vein oxygen saturation.
Monitoring of cerebral oxygenation is considered to be of great importance in minimizing secondary hypoxic and ischemic brain damage following severe head injury. Although the threshold for cerebral hypoxia in jugular bulb oximetry (measurement of O2 saturation in the jugular vein (SjvO2)) is generally accepted to be 50% oxygen saturation, a comparable value in brain tissue PO2 (PtiO2) monitoring, a new method for direct assessment of PO2 in the cerebral white matter, has not yet been established. Hence, the purpose of this study was to compare brain PtiO2 with SjvO2 in severely head injured patients during phases of reduced cerebral perfusion pressure (CPP) to define a threshold in brain PtiO2 monitoring. ⋯ This study demonstrates that monitoring brain PtiO2 is a safe, reliable, and sensitive diagnostic method to follow cerebral oxygenation. In comparison to SjvO2, PtiO2 is more suitable for long-term monitoring. It can be used to minimize episodes of secondary cerebral maloxygenation after severe head injury and may, hopefully, improve the outcome in severely head injured patients.
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Journal of neurosurgery · Nov 1996
Magnetic resonance imaging for the evaluation of patients with occult cervical spine injury.
Because it is often difficult to diagnose accurately the structurally intact cervical spine after acute trauma, a series of patients was evaluated with magnetic resonance (MR) imaging to assess its efficacy for the evaluation and clearance of the cervical spine in a trauma victim in the early posttrauma period. Ultralow-field MR imaging was used to evaluate 174 posttraumatic patients in whom physical findings indicated the potential for spine injury or minor radiographic findings indicated injury. This series includes only those patients who did not appear to harbor disruption of spinal integrity on the basis of a routine x-ray film. ⋯ A negative MR image should be considered as confirmation of a negative or "cleared" subaxial cervical spine. Diagnostic and patient management algorithms may be appropriately tailored by this information. Thus, MR imaging is useful for early acute posttrauma assessment in a very select group of patients.
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Journal of neurosurgery · Nov 1996
Clinical significance of diffuse dural enhancement detected by magnetic resonance imaging.
This study was performed to determine the clinical significance of diffuse dural enhancement (DDE) detected by magnetic resonance (MR) imaging and to typify enhancing patterns related to inflammatory or metastatic causes. The authors retrospectively evaluated the clinical, imaging, and laboratory characteristics of 20 consecutive patients with DDE. Those with DDE and an underlying neoplastic disease (13 patients) were compared to 11 consecutive patients with cytological evidence of neoplastic leptomeningeal metastasis evaluated by MR imaging. ⋯ The findings indicate that DDE is not a radiographic hallmark of leptomeningeal metastasis in spite of the similarities in clinical manifestations (for example, headache and cranial polyneuropathy). Nonetheless, DDE is most frequently associated with metastatic malignancies and particularly with skull metastases and CSF leak. Special MR techniques can discern the underlying cause and elucidate the disparity in the pathophysiological mechanisms leading to DDE.
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Diffuse cerebral swelling after severe traumatic brain injury (TBI) develops more commonly in children than adults; however, models of diffuse brain injury in immature animals are lacking. The authors developed a new model of diffuse severe TBI in immature rats by modifying a recently described closed head injury model for adult rats. A total of 105 Sprague-Dawley immature rats (17 days old; average weight 38.5 +/- 5.46 g) were subjected to head impact using variable weights (0 g (sham), 75 g, 100 g, or 125 g) delivered from a height of 2 m onto a metal disk cemented to the intact cranium. ⋯ Weight loss, acute physiological instability, and acute neurological deficits were also indicative of an SI. Mortality was eliminated when ventilatory support was used during the peritrauma period. This model should be useful in studying the response of the immature rat to diffuse severe TBI.
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Journal of neurosurgery · Nov 1996
Cerebral blood flow and vasoresponsivity within and around cerebral contusions.
There is increasing evidence that regional ischemia plays a major role in secondary brain injury. Although the cortex underlying subdural hematomas seems particularly vulnerable to ischemia, little is known about the adequacy of cerebral blood flow (CBF) or the vasoresponsivity within the vascular bed of contusions. The authors used the xenon-enhanced computerized tomography (CT) CBF technique to define the CBF and vasoresponsivity of contusions, pericontusional parenchyma, and the remainder of the brain 24 to 48 hours after severe closed head injury in 10 patients: six patients with one contusion and four with two contusions, defined as mixed or high-density lesions on CT scanning. ⋯ Intracontusional CBF is significantly reduced relative to surrounding brain parenchyma, and CO2 vasoresponsivity is usually present. In the contusion and the surrounding parenchyma, vasoresponsivity may be nearly three times normal, suggesting hypersensitivity to hyperventilation therapy. Given this possible hypersensitivity and relative hypoperfusion within and around cerebral contusions, these lesions are particularly vulnerable to secondary injury such as that which may be caused by hypotension or aggressive hyperventilation.