Acute secondary adrenal insufficiency after traumatic brain injury: a prospective study.

OBJECTIVE: To determine the prevalence, time course, clinical characteristics, and effect of adrenal insufficiency (AI) after traumatic brain injury (TBI). DESIGN: Prospective intensive care unit-based cohort study. SETTING: Three level 1 trauma centers. PATIENTS: A total of 80 patients with moderate or severe TBI (Glasgow Coma Scale score, 3-13) and 41 trauma patients without TBI (Injury Severity Score, >15) enrolled between June 2002 and November 2003. MEASUREMENTS: Serum cortisol and adrenocorticotropic hormone levels were drawn twice daily for up to 9 days postinjury; AI was defined as two consecutive cortisols of < or =15 microg/dL (25th percentile for extracranial trauma patients) or one cortisol of < 5 microg/dL. Principal outcome measures included: injury characteristics, hemodynamic data, usage of vasopressors, metabolic suppressive agents (high-dose pentobarbital and propofol), etomidate, and AI status. MAIN RESULTS: AI occurred in 42 TBI patients (53%). Adrenocorticotropic hormone levels were lower at the time of AI (median, 18.9 vs. 36.1 pg/mL; p = .0001). Compared with patients without AI, those with AI were younger (p = .01), had higher injury severity (p = .02), had a higher frequency of early ischemic insults (hypotension, hypoxia, severe anemia) (p = .02), and were more likely to have received etomidate (p = .049). Over the acute postinjury period, patients with AI had lower trough mean arterial pressure (p = .001) and greater vasopressor use (p = .047). Mean arterial pressure was lower in the 8 hrs preceding a low (< or =15 microg/dL) cortisol level (p = .003). There was an inverse relationship between cortisol levels and vasopressor use (p = .0005) and between cortisol levels within 24 hrs of injury and etomidate use (p = .002). Use of high-dose propofol and pentobarbital was strongly associated with lower cortisol levels (p < .0001). CONCLUSIONS: Approximately 50% of patients with moderate or severe TBI have at least transient AI. Younger age, greater injury severity, early ischemic insults, and the use of etomidate and metabolic suppressive agents are associated with AI. Because lower cortisol levels were associated with lower blood pressure and higher vasopressor use, consideration should be given to monitoring cortisol levels in intubated TBI patients, particularly those receiving high-dose pentobarbital or propofol. A randomized trial of stress-dose hydrocortisone in TBI patients with AI is underway.

Relationship between valve opening pressure, body position, and intracranial pressure in normal pressure hydrocephalus: paradigm for selection of programmable valve pressure setting.

OBJECTIVE: There is little scientific basis for guidance in selecting the optimal valve for the treatment of normal pressure hydrocephalus. The aim of this study was to determine the programmable valve opening pressure setting that would result in a slight reduction in intracranial pressure (ICP) after a ventriculoperitoneal shunt is implanted. We also assessed whether shunt-induced ICP could be predicted on the basis of a simple hydrodynamic equation. METHODS: In this prospective study of 11 patients with normal pressure hydrocephalus, ICP was measured before and after implantation of a shunt incorporating a programmable valve without an antisiphon device. Pressure measurements, including intraperitoneal pressure, were recorded at body angles ranging from 0 to 55 degrees and at valve settings ranging from 30 to 200 mm H(2)O. Measured ICP values were compared with values computed using a simple hydrodynamic equation. RESULTS: Even at a valve setting greater than the mean baseline ICP (200 mm H(2)O), the supine ICP was significantly lower than the baseline value (baseline ICP, 164 +/- 64 mm H(2)O; postoperative ICP, 125 +/- 69 mm H(2)O, P = 0.04). Valve pressure did not equate 1:1 with the measured postoperative ICP. Comprehensive ICP measurements at upright body positions demonstrated a stepwise reduction in ICP rather than a precipitous decline as a result of so-called siphoning. CONCLUSION: This study indicates that very high valve opening pressure settings may be optimal for the initial treatment of normal pressure hydrocephalus. The relationship between ICP and opening pressure valves is linear but not predicted by simple hydrodynamics.

Endonasal transsphenoidal removal of tuberculum sellae meningiomas: technical note.

OBJECTIVE: Tuberculum sellae meningiomas traditionally have been removed through a transcranial approach. More recently, the sublabial transsphenoidal approach has been used to remove such tumors. Here, we describe use of the direct endonasal transsphenoidal approach for removal of suprasellar meningiomas. METHODS: Three women, aged 32, 34, and 55 years, each sought treatment for visual loss and headaches. In each patient, magnetic resonance imaging (MRI) showed a suprasellar mass causing optic chiasmal and optic nerve compression (average size, 2 x 2 cm). All three patients underwent tumor removal via an endonasal approach with the operating microscope. Suprasellar exposure was facilitated by removal of the posterior planum sphenoidale. Ultrasound was used to help define tumor location before dural opening. The extent of tumor removal was verified with angled endoscopes in all patients, and with intraoperative MRI in one patient. The surgical dural and bony defects were repaired in all patients with abdominal fat, titanium mesh, and 2 to 3 days of cerebrospinal fluid lumbar drainage. Nasal packing was not used. RESULTS: There were no postoperative cerebrospinal fluid leaks or meningitis. One patient required a reoperation 2 weeks after surgery to reduce the size of her fat graft, which was causing optic nerve compression; within 24 hours, her vision rapidly improved. At 3 months after surgery, all three patients had normal vision, no new endocrinopathy, and no residual tumor on MRI. At 10 months after surgery, one patient had a small asymptomatic tumor regrowth seen on MRI. CONCLUSION: The endonasal approach with the operating microscope appears to be an effective minimally invasive method for removing relatively small midline tuberculum sellae meningiomas. Intraoperative ultrasound, the micro-Doppler probe, and angled endoscopes are useful adjuncts for safely and completely removing such tumors. Longer follow-up is needed to monitor for tumor recurrence in these patients.

Cerebral hemispherectomy in pediatric patients with epilepsy: comparison of three techniques by pathological substrate in 115 patients.

OBJECT: Cerebral hemispherectomy for intractable seizures has evolved over the past 50 years, and current operations focus less on brain resection and more on disconnection. In addition, cases involving cortical dysplasia and Rasmussen encephalitis are being identified and surgically treated in younger individuals. Few studies have been conducted to compare whether there are perioperative differences based on hemispherectomy technique and/or pathological substrate in pediatric patients with epilepsy. METHODS: In this study the authors compared, stratified by disease, anatomical (37 cases) and Rasmussen functional hemispherectomy (32 cases) with a new modified lateral hemispherotomy (46 cases). Pathological processes included cortical dysplasia (55 cases), Rasmussen encephalitis (21 cases), infarction/ischemia (27 cases), and other/miscellaneous (12 cases). The authors found differences in perioperative clinical factors based on operative technique and/or pathological substrate. In terms of technique, the lateral hemispherotomy was associated with the least intraoperative blood loss, shortest intensive care unit stay, and lowest complication rate. The anatomical hemispherectomy was associated with the longest hospital stay, delayed oral food intake, highest postsurgery fevers, and the highest incidence of shunt requirement. The functional hemispherectomy was associated with the highest reoperation rate for recurrent seizures (25%). In terms of pathology, patients with cortical dysplasia were the youngest at surgery, suffered the greatest amount of blood loss, and required the longest operative/anesthesia times compared with the other pathologically defined groups. Postoperative seizure control (range 0.5-2 years) was not statistically different according to technique or disease process and was similar to that in cases of pediatric temporal lobe epilepsy. CONCLUSIONS: The authors found differences in perioperative risks and hospital course but not postsurgery seizure control, which vary by hemispherectomy technique and/or disease process. The modified lateral hemispherotomy approach offers various advantages related to operative blood loss and reoperation compared with anatomical and functional hemispherectomies that are especially relevant in younger patients with cortical dysplasia and Rasmussen encephalitis with small and/or malformed ventricles.