Steven M. Toutant, Michael M. Todd and Harvey M. Shapiro
✓ An easily used, sensitive, and highly accurate method of measuring movement of the exposed brain surface is described. The technique may be useful to both neurophysiologists and neurosurgeons.
Pigmented villonodular synovitis associated with pathological fracture of the odontoid and atlantoaxial instability
Case report and review of the literature
Michael A. Finn, Todd D. McCall and Meic H. Schmidt
✓Pigmented villonodular synovitis (PVNS) is a proliferative disorder of the synovium with a predisposition for the appendicular skeleton. Rarely PVNS can arise from the spine, where this disorder usually presents with localized or radicular pain secondary to involvement of the posterior elements. The authors report the case of an 82-year-old woman who presented with long-standing neck pain and acute upper-extremity numbness and weakness. Computed tomography imaging revealed a mixed sclerotic and lucent lesion affecting the dens and right lateral mass of C-2. There was also a pathological fracture at the base of the dens with 8 mm of anterior dens displacement. Magnetic resonance imaging demonstrated a diffusely infiltrative process that was nonenhancing. Because of instability, the patient underwent transarticular screw fixation, and a biopsy of the lesion was also performed at this time. Histopathological analysis was consistent with a diagnosis of PVNS. To the authors' knowledge, this is the first report of PVNS involving the C-2 vertebra or causing a pathological fracture.
Michael M. Todd, Concezione Tommasino and Suzanne Moore
✓ In view of a growing interest in the resuscitative use of hypertonic saline solutions, the authors have examined the cerebral effects of isovolemic hemodilution carried out over 1 hour (hematocrit decreased from 40% to 20%, stable arterial and right arterial pressures), using a hypertonic lactated Ringer's solution (HT-LR:Na+ 252 mEq/liter, osmolality 480 mOsm/liter). Experiments were carried out in anesthetized ventilated rabbits. Measured variables included cerebral blood flow (using the H2 clearance method), intracranial pressure (ICP), the electroencephalogram, spinal cord and skeletal muscle water content (%H2O), and the specific gravity of small (10- to 30-mg) tissue samples taken from different areas of the left hemisphere (including the cortex, thalamus, internal capsule, and hippocampus). The changes produced by HT-LR were compared with those seen in both undiluted control animals and in rabbits hemodiluted with normal saline (Na+ 155 mEq/liter, osmolality 310 mOsm/liter). The results demonstrate that hemodilution with HT-LR leads to the expected increases in serum Na+ and osmolality (158 ± 6 mEq/liter and 320 ± 5 mOsm/kg, respectively, mean ± standard deviation) and that these were accompanied by reductions in the %H2O of all cerebral and extracerebral tissues, increases in the specific gravity of all tissue regions studied, and a decrease in ICP (1.9 ± 0.7 mm Hg). By contrast, rabbits with hemodilution by normal saline showed no changes in either %H2O or specific gravity, but had significant increases in ICP (3.3 ± 1.3 mm Hg). Cerebral blood flow increased in all animals hemodiluted with either HT-LR or normal saline by a combined average of +29 ml/100 gm/min.
Although these studies were performed in neurologically normal animals, the combination of cerebral changes seen with HT-LR (cerebral dehydration, less peripheral edema, decreased ICP but with increased cerebral blood flow) suggests that this approach may have some advantages over the use of isotonic fluids, and may have some utility in the resuscitation of head-injured patients.
Todd M. Goldenberg and Michael B. Pritz
✓ A simple technique to lengthen the distal catheter of ventriculoperitoneal shunts is described. This method, which utilizes a guidewire, has been successful in elective shunt revisions in eight children.
Kelly B. Mahaney, Michael M. Todd, Emine O. Bayman and James C. Torner
Subarachnoid hemorrhage (SAH) results in significant morbidity and mortality, even among patients who reach medical attention in good neurological condition. Many patients have neurological decline in the perioperative period, which contributes to long-term outcomes. The focus of this study is to characterize the incidence of, characteristics predictive of, and outcomes associated with acute postoperative neurological deterioration in patients undergoing surgery for ruptured intracranial aneurysm.
The Intraoperative Hypothermia for Aneurysm Surgery Trial (IHAST) was a multicenter randomized clinical trial that enrolled 1001 patients and assesssed the efficacy of hypothermia as neuroprotection during surgery to secure a ruptured intracranial aneurysm. All patients had a radiographically confirmed SAH, were classified as World Federation of Neurosurgical Societies (WFNS) Grade I–III immediately prior to surgery, and underwent surgery to secure the ruptured aneurysm within 14 days of SAH. Neurological assessment with the National Institutes of Health Stroke Scale (NIHSS) was performed preoperatively, at 24 and 72 hours postoperatively, and at time of discharge. The primary outcome variable was a dichotomized scoring based on an IHAST version of the Glasgow Outcome Scale (GOS) in which a score of 1 represents a good outcome and a score > 1 a poor outcome, as assessed at 90-days' follow-up. Data from IHAST were analyzed for occurrence of a postoperative neurological deterioration. Preoperative and intraoperative variables were assessed for associations with occurrence of postoperative neurological deterioration. Differences in baseline, intraoperative, and postoperative variables and in outcomes between patients with and without postoperative neurological deterioration were compared with Fisher exact tests. The Wilcoxon rank-sum test was used to compare variables reported as means. Multiple logistic regression was used to adjust for covariates associated with occurrence of postoperative deficit.
Acute postoperative neurological deterioration was observed in 42.6% of the patients. New focal motor deficit accounted for 65% of postoperative neurological deterioration, while 60% was accounted for using the NIHSS total score change and 51% by Glasgow Coma Scale score change. Factors significantly associated with occurrence of postoperative neurological deterioration included: age, Fisher grade on admission, occurrence of a procedure prior to aneurysm surgery (ventriculostomy), timing of surgery, systolic blood pressure during surgery, ST segment depression during surgery, history of abnormality in cardiac valve function, use of intentional hypotension during surgery, duration of anterior cerebral artery occlusion, intraoperative blood loss, and difficulty of aneurysm exposure. Of the 426 patients with postoperative neurological deterioration at 24 hours after surgery, only 46.2% had a good outcome (GOS score of 1) at 3 months, while 77.7% of those without postoperative neurological deterioration at 24 hours had a good outcome (p < 0.05)
Neurological injury incurred perioperatively or in the acute postoperative period accounts for a large percentage of poor outcomes in patients with good admission WFNS grades undergoing surgery for aneurysmal SAH. Avoiding surgical factors associated with postoperative neurological deterioration and directing investigative efforts at developing improved neuroprotection for use in aneurysm surgery may significantly improve long-term neurological outcomes in patients with SAH.
Kelly B. Mahaney, Michael M. Todd and James C. Torner
The past 30 years have seen a shift in the timing of surgery for aneurysmal subarachnoid hemorrhage (SAH). Earlier practices of delayed surgery that were intended to avoid less favorable surgical conditions have been replaced by a trend toward early surgery to minimize the risks associated with rebleeding and vasospasm. Yet, a consensus as to the optimal timing of surgery has not been reached. The authors hypothesized that earlier surgery, performed using contemporary neurosurgical and neuroanesthesia techniques, would be associated with better outcomes when using contemporary management practices, and sought to define the optimal time interval between SAH and surgery.
Data collected as part of the Intraoperative Hypothermia for Aneurysm Surgery Trial (IHAST) were analyzed to investigate the relationship between timing of surgery and outcome at 3 months post-SAH. The IHAST enrolled 1001 patients in 30 neurosurgical centers between February 2000 and April 2003. All patients had a radiographically confirmed SAH, were World Federation of Neurosurgical Societies Grades I–III at the time of surgery, and underwent surgical clipping of the presumed culprit aneurysm within 14 days of the date of hemorrhage. Patients were seen at 90-day follow-up visits. The primary outcome variable was a Glasgow Outcome Scale score of 1 (good outcome). Intergroup differences in baseline, intraoperative, and postoperative variables were compared using the Fisher exact tests. Variables reported as means were compared with ANOVA. Multiple logistic regression was used for multivariate analysis, adjusting for covariates. A p value of less than 0.05 was considered to be significant.
Patients who underwent surgery on Days 1 or 2 (early) or Days 7–14 (late) (Day 0 = date of SAH) fared better than patients who underwent surgery on Days 3–6 (intermediate). Specifically, the worst outcomes were observed in patients who underwent surgery on Days 3 and 4. Patients who had hydrocephalus or Fisher Grade 3 or 4 on admission head CT scans had better outcomes with early surgery than with intermediate or late surgery.
Early surgery, in good-grade patients within 48 hours of SAH, is associated with better outcomes than surgery performed in the 3- to 6-day posthemorrhage interval. Surgical treatment for aneurysmal SAH may be more hazardous during the 3- to 6-day interval, but this should be weighed against the risk of rebleeding.
Todd A. Patrick, Caterina Giannini, Michael J. Ebersold and Michael J. Link
✓ Metastatic seeding or iatrogenic implantation of numerous types of primary central nervous system tumors, typically along cerebrospinal fluid pathways, is a frequently described albeit rare phenomenon and has never been reported in association with vestibular schwannoma (VS). The authors present a case of inadvertent surgical implantation of VS into the cerebellar hemisphere during resection of a recurrent VS in the cerebellopontine angle and internal auditory canal. A 42-year-old man presented with a 2.5-cm right VS that was removed without complication via a retrosigmoid approach. Routine imaging performed 5 years later revealed a 1.5-cm recurrence of the VS that was subsequently removed by reopening the retrosigmoid craniotomy. Five years later—10 years after initial presentation—follow-up imaging revealed a 1-cm recurrence of the VS and a separate 2.2-cm tumor in the inferior cerebellar parenchyma with surrounding edema. Both tumors were removed without complication by reopening the previous retrosigmoid craniotomy. Histological evaluation of these tumors revealed features typical of VS and similar to those of the tissue obtained from the two prior resections. Given the similarities among these tumors in pathological appearance and mitotic index, the presence of the intraparenchymal cerebellar schwannoma was probably due to intraoperative iatrogenic implantation.