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Brain Abscess

H. Richard Winn

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Cerebral blood flow

Warren R. Selman and H. Richard Winn

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Toward a rational treatment of Chiari I malformation and syringomyelia

Richard G. Ellenbogen, Rocco A. Armonda, Dennis W. W. Shaw, and H. Richard Winn

In patients with Chiari I malformation with and without associated syringomyelia, aberrant cerebrospinal fluid (CSF) dynamics and a spectrum of posterior fossa pathological findings are demonstrated. In this study, the authors test the validity of using prospective cardiac-gated phase-contrast cine-mode magnetic resonance (MR) imaging to define the malformation, delineate its pathophysiology, and assist in implementing a rational treatment plan.

Eighty-five cases were prospectively analyzed using cine MR imaging. Sixty-five patients, adults and children, with symptomatic Chiari malformation, with and without syringomyelia, were surgically treated from 1990 to 1999. All patients underwent pre- and postoperative cine MR evaluation. Ten patients were treated after a previous surgical procedure had failed. To establish CSF flow characteristics and normative CSF profiles, 20 healthy volunteers were examined.

Compared with normal volunteers, in Chiari I malformation patients with and without syringomyelia, uniformly abnormal craniocervical junction CSF flow profiles were revealed. After intradural exploration, nearly all patients with Chiari I malformation experienced clinical improvement and CSF flow profiles, paralleling those of normal volunteers, were shown. In all patients in whom treatment had failed, abnormal preoperative CSF flow profiles, which correlated with suspected physiological abnormalities and the pathological findings noted at reoperation, were demonstrated.

Symptomatic Chiari I malformation is a dynamic process characterized by the impaction of the hindbrain in an abnormal posterior fossa. This compression obstructs the normal venting of CSF in and out of the craniocervical sub-arachnoid space, throughout the cardiac cycle. Therefore, decompression or enlargement of the posterior fossa to establish normal CSF pathways should be the primary goal of surgical intervention. Aberrant CSF flow appears to be only one aspect of the pathological condition found in patients with Chiari I malformation. Arachnoid scarring in the posterior fossa and selective vulnerability of the spinal cord may also be factors in the pathogenesis and maintenance of associated syringomyelia. Phase-contrast cine MR imaging is a useful tool in defining physiological and anatomical problems in patients with Chiari I and syringomyelia, and it can help guide an appropriate primary or salvage surgical therapy.

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Cerebral arteriovenous oxygen difference: a predictor of cerebral infarction and outcome in patients with severe head injury

Peter D. Le Roux, David W. Newell, Arthur M. Lam, M. Sean Grady, and H. Richard Winn

Jugular bulb oxygen monitoring can be used to estimate the adequacy of cerebral blood flow to support cerebral metabolism after severe head injury. In the present study, the authors studied the cerebral arteriovenous oxygen difference (AVDO2) before and after treatment in 32 head-injured patients (Glasgow Coma Scale scores ¾ 8) to examine the relationships among AVDO2 and cerebral perfusion pressure (CPP), delayed cerebral infarction, and outcome. Fifteen patients (Group A) underwent craniotomy for hematoma evacuation and 17 (Group B) received mannitol for sustained intracranial hypertension (intracranial pressure > 20 mm Hg, > 10 minutes). Radiographic evidence of delayed cerebral infarction was observed in 14 patients. Overall, 17 patients died or were severely disabled. Cerebral AVDO2 was elevated before craniotomy or mannitol administration; the mean AVDO2 for all patients before treatment was 8.6 ± 1.8 vol%. Following craniotomy or mannitol administration, the AVDO2 decreased in 27 patients and increased in five patients (mean AVDO2 6.2 ± 2.1 vol% in all patients; 6 ± 1.9 vol% in Group A; and 6.4 ± 2.4 vol% in Group B). The mean CPP was 75 ± 9.8 mm Hg and no relationship with AVDO2 was demonstrated. Before treatment, the AVDO2 was not associated with delayed cerebral infarction or outcome. By contrast, a limited improvement in elevated AVDO2 after craniotomy or mannitol administration was significantly associated with delayed cerebral infarction (Group A: p < 0.001; Group B: p < 0.01). Similarly, a limited improvement in elevated AVDO2 after treatment was significantly associated with an unfavorable outcome (Group A: p < 0.01; Group B: p < 0.001). In conclusion, these findings strongly indicate that, despite adequate cerebral perfusion, limited improvement in elevated cerebral AVDO2 after treatment consisting of either craniotomy or mannitol administration may be used to help predict delayed cerebral infarction and poor outcome after traumatic brain injury.

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Comparison of balloon angioplasty and papaverine infusion for the treatment of vasospasm following aneurysmal subarachnoid hemorrhage

J. Paul Elliott, David W. Newell, Derek J. Lam, Joseph M. Eskridge, Colleen M. Douville, Peter D. LeRoux, David H. Lewis, Marc R. Mayberg, M. Sean Grady, and H. Richard Winn

The authors used daily transcranial Doppler (TCD) evaluation to test the hypothesis that balloon angioplasty is superior to papaverine infusion for the treatment of proximal anterior circulation arterial vasospasm following subarachnoid hemorrhage (SAH). Between 1989 and 1995, 125 vasospastic distal internal carotid artery or proximal middle cerebral artery vessel segments were treated in 52 patients. Blood flow velocities of the involved vessels were assessed using TCD monitoring in relation to the day of treatment with balloon angioplasty or papaverine infusion. Balloon angioplasty and papavarine infusion cohorts were compared based on mean pretreatment velocity and mean posttreatment velocity at 24 and 48 hours using the one-tailed, paired-samples t-test. Balloon angioplasty alone was performed in 101 vessel segments (81%) in 39 patients (75%), whereas papaverine infusion alone was used in 24 vessel segments (19%) in 13 patients (25%). Although repeated treatment following balloon angioplasty was needed in only one vessel segment, repeated treatment following papaverine infusion was required in 10 vessel segments (42%) in six patients because of recurrent vasospasm (p < 0.001). Seven vessel segments (29%) with recurrent spasm following papaverine infusion were treated with balloon angioplasty. Although vessel segments treated with papaverine demonstrated a 20% mean decrease in blood flow velocity (p < 0.009) on posttreatment Day 1, velocities were not significantly lower than pretreatment levels by posttreatment Day 2 (p = 0.133). Balloon angioplasty resulted in a 45% mean decrease in velocity to a normal level following treatment (p < 0.001), which was sustained. The authors conclude that balloon angioplasty is superior to papaverine infusion for the permanent treatment of proximal anterior circulation vasospasm following aneurysmal SAH.

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Cerebral autoregulation following minor head injury

Elisabeth C. Jünger, David W. Newell, Gerald A. Grant, Anthony M. Avellino, Saadi Ghatan, Colleen M. Douville, Arthur M. Lam, Rune Aaslid, and H. Richard Winn

The purpose of this study was to determine whether patients with minor head injury experience impairments in cerebral autoregulation. Twenty-nine patients with minor head injuries defined by Glasgow Coma Scale (GCS) scores of 13 to 15 underwent testing of dynamic cerebral autoregulation within 48 hours of their injury using continuous transcranial Doppler velocity recordings and blood pressure recordings. Twenty-nine age-matched normal volunteers underwent autoregulation testing in the same manner to establish comparison values. The function of the autoregulatory response was assessed by the cerebral blood flow velocity response to induced rapid brief changes in arterial blood pressure and measured as the autoregulation index (ARI).

Eight (28%) of the 29 patients with minor head injury demonstrated poorly functioning or absent cerebral autoregulation versus none of the controls, and this difference was highly significant (p = 0.008). A significant correlation between lower blood pressure and worse autoregulation was found by regression analysis in head-injured patients (r = 0.6, p < 0.001); however, lower blood pressure did not account for the autoregulatory impairment in all patients. Within this group of head-injured patients there was no correlation between ARI and initial GCS or 1-month Glasgow Outcome Scale scores. This study indicates that a significant number of patients with minor head injury may have impaired cerebral autoregulation and may be at increased risk for secondary ischemic neuronal damage.

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Methylprednisolone or tirilazad mesylate administration after acute spinal cord injury: 1-year follow up

Results of the third National Acute Spinal Cord Injury randomized controlled trial

Michael B. Bracken, Mary Jo Shepard, Theodore R. Holford, Linda Leo-Summers, E. Francois Aldrich, Mahmood Fazl, Michael G. Fehlings, Daniel L. Herr, Patrick W. Hitchon, Lawrence F. Marshall, Russ P. Nockels, Valentine Pascale, Phanor L. Perot Jr., Joseph Piepmeier, Volker K. H. Sonntag, Franklin Wagner, Jack E. Wilberger, H. Richard Winn, and Wise Young

Object

A randomized double-blind clinical trial was conducted to compare neurological and functional recovery and morbidity and mortality rates 1 year after acute spinal cord injury in patients who had received a standard 24-hour methylprednisolone regimen (24MP) with those in whom an identical MP regimen had been delivered for 48 hours (48MP) or those who had received a 48-hour tirilazad mesylate (48TM) regimen.

Methods

Patients for whom treatment was initiated within 3 hours of injury showed equal neurological and functional recovery in all three treatment groups. Patients for whom treatment was delayed more than 3 hours experienced diminished motor function recovery in the 24MP group, but those in the 48MP group showed greater 1-year motor recovery (recovery scores of 13.7 and 19, respectively, p = 0.053).A greater percentage of patients improving three or more neurological grades was also observed in the 48MP group (p = 0.073). In general, patients treated with 48TM recovered equally when compared with those who received 24MP treatments. A corresponding recovery in self care and sphincter control was seen but was not statistically significant. Mortality and morbidity rates at 1 year were similar in all groups.

Conclusions

For patients in whom MP therapy is initiated within 3 hours of injury, 24-hour maintenance is appropriate. Patients starting therapy 3 to 8 hours after injury should be maintained on the regimen for 48 hours unless there are complicating medical factors.