Association between visual parameters and neuroimaging features of idiopathic intracranial hypertension

Authors: Padhye LV, Van Stavern GP, Sharma A, Viets R, Huecker JB, Gordon MO.

BACKGROUND/AIMS: Papilledema refers to optic disc swelling resulting from high intracranial pressure (ICP). The precise mechanism by which papilledema occurs remains uncertain. Although orbital neuroimaging features associated with papilledema are well-described, it is unclear whether these findings correlate with visual function. Idiopathic Intracranial Hypertension (IIH) is a condition in which the intracranial pressure is elevated with no obvious cause, causing papilledema and visual loss. The utility of papilledema and IIH neuroimaging findings as a surrogate marker for visual loss, or a predictor of visual loss, is understudied. This retrospective cross-sectional review aims to correlate parameters of visual function with orbital magnetic resonance imaging (MRI) findings.
METHODS: Patients meeting criteria for IIH who had received orbital imaging within 4weeks of examination were included. Visual parameters of papilledema grade, visual field mean deviation, and visual acuity were correlated with neuroimaging features, including optic nerve thickness, and optic nerve sheath thickness, among others. All MRI scans were reviewed by a neuroradiologist blinded to clinical status. Spearman rank correlations and t-tests were generated with SAS (v9.2).
RESULTS: Thirty five patients were included. No significant relationships were found between the main visual parameters of papilledema grade and visual field mean deviation, and MRI findings.
CONCLUSIONS: We found no significant correlation between visual parameters and imaging features of papilledema. This might indicate that MRI features may provide insight into the structural changes that occur in papilledema, but may not be helpful when making clinical management decisions for patients with IIH in particular, and papilledema in general.

Acute intracranial hematoma formation following excision of a cervical subdural tumor: a report of two cases and literature review

Authors: Ma X, Zhang Y, Wang T, Li G, Zhang G, Khan H, Xiang H, Chen B.

An intracranial hematoma is a rare, yet significant, complication following spinal surgery. The authors describe two cases with acute intracranial hematoma formation after excision of a cervical subdural schwannoma. One was a 14-year-old girl who developed bilateral intracranial extradural hematomas immediately following excision of the C4 subdural schwannoma. The other was a 59-year-old woman who had an acute cerebellar hematoma after removal of the C2-C5 subdural schwannoma. During the surgeries of both cases, spinal dura was partially removed together with the tumor and the dural sac could not be repaired, resulting in large amounts of intraoperative CSF loss and persistent postoperative CSF leakage. Both patients failed to regain consciousness from anesthesia after surgery, and a cranial CT scan identified large intracranial hematomas. Urgent hematoma evacuation was ultimately performed to save the patients. Based on the authors' experience and literature review, a conclusion was drawn that considerable CSF leakage and a sharp decrease of CSF pressure are common features during the excision of a spinal subdural tumor, which may lead to acute intracranial hematomas. Continual postoperative monitoring in patients with this condition should be of a very high priority. A CT or MRI should be immediately investigated to exclude intracranial hematomas for any patient with delayed emergence from anesthesia following spinal surgery. Hematoma evacuation is indispensable once an intracranial hematoma is identified in the patient who fails to regain consciousness from anesthesia post surgery. Furthermore, the possible pathophysiological mechanisms responsible for the formation of an intracranial hematoma after spinal procedures, particularly after manipulations of a cervical subdural tumor, are discussed.

Measuring and Monitoring ICP in Neurocritical Care: Results from a National Practice Survey

Authors: Olson DM, Batjer HH, Abdulkadir K, Hall CE.

INTRODUCTION: The use of intracranial pressure (ICP) monitors is nearly synonymous with Neurocritical Care. Recent studies in nursing literature have report high levels of practice variance associated with ICP monitoring and treatment. There are no recent practice surveys to describe how critical care physicians and nurses who are familiar with ICP management provide care to their patients.
METHODS: A short survey was developed and disseminated electronically to the members of the Neurocritical Care Society.
RESULTS: The summary from 241 professionals provides evidence that there is significant practice variation associated with ICP monitoring and management.
CONCLUSION: The results highlight the need to develop standardized approaches to measuring, monitoring, recording, and treating ICP.

Beyond intracranial pressure: optimization of cerebral blood flow, oxygen, and substrate delivery after traumatic brain injury

Authors: Bouzat P, Sala N, Payen JF, Oddo M.

Monitoring and management of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) is a standard of care after traumatic brain injury (TBI). However, the pathophysiology of so-called secondary brain injury, i.e., the cascade of potentially deleterious events that occur in the early phase following initial cerebral insult---after TBI, is complex, involving a subtle interplay between cerebral blood flow (CBF), oxygen delivery and utilization, and supply of main cerebral energy substrates (glucose) to the injured brain. Regulation of this interplay depends on the type of injury and may vary individually and over time. In this setting, patient management can be a challenging task, where standard ICP/CPP monitoring may become insufficient to prevent secondary brain injury. Growing clinical evidence demonstrates that so-called multimodal brain monitoring, including brain tissue oxygen (PbtO2), cerebral microdialysis and transcranial Doppler among others, might help to optimize CBF and the delivery of oxygen/energy substrate at the bedside, thereby improving the management of secondary brain injury. Looking beyond ICP and CPP, and applying a multimodal therapeutic approach for the optimization of CBF, oxygen delivery, and brain energy supply may eventually improve overall care of patients with head injury. This review summarizes some of the important pathophysiological determinants of secondary cerebral damage after TBI and discusses novel approaches to optimize CBF and provide adequate oxygen and energy supply to the injured brain using multimodal brain monitoring.

Viral-Induced Intracranial Hypertension Mimicking Pseudotumor Cerebri

Authors: Ravid S, Shachor-Meyouhas Y, Shahar E, Kra-Oz Z, Kassis I.

BACKGROUND: Pseudotumor cerebri or idiopathic intracranial hypertension is characterized by normal spinal fluid composition and increased intracranial pressure in the absence of a space-occupying lesion.
METHODS: This study describes a subgroup of 10 patients with the same typical presenting symptoms (headache, vomiting, and papilledema) but without nuchal rigidity, meningeal signs, or change in mental status. Patients had normal neuroimaging studies and intracranial hypertension but also pleocytosis in the cerebrospinal fluid, suggesting central nervous system infection. From the results it can be hypothesized that those children represent a unique subgroup of viral-induced intracranial hypertension when comparing their risk factors, clinical course, treatment, and outcome with 58 patients who had idiopathic intracranial hypertension.
RESULTS: All patients with viral-induced intracranial hypertension presented with papilledema but none had reduced visual acuity or abnormal visual fields, compared with 20.7% of patients who had idiopathic intracranial hypertension. They also responded better to treatment with acetazolamide, needed a shorter duration of treatment (7.7 ± 2.6 months vs 12.2 ± 6.3 months, P = 0.03), and had no recurrences.
CONCLUSION: The results suggest that children who fulfill the typical presenting signs and symptoms and all diagnostic criteria for pseudotumor cerebri other than the normal cerebrospinal fluid component may represent a unique subgroup of viral-induced intracranial hypertension and should be managed accordingly. The overall prognosis is excellent.
Copyright © 2013 Elsevier Inc. All rights reserved.

Complications associated with prolonged hypertonic saline therapy in children with elevated intracranial pressure

Authors: Gonda DD, Meltzer HS, Crawford JR, Hilfiker ML, Shellington DK, Peterson BM, Levy ML.

OBJECTIVES: Safe upper limits for therapeutic hypernatremia in the treatment of intracranial hypertension have not been well established. We investigated complications associated with hypernatremia in children who were treated with prolonged infusions of hypertonic saline.
DESIGN: Retrospective chart analysis.
SETTING: PICU in university-affiliated children's hospital.
PATIENTS: All children from 2004 to 2009 requiring intracranial pressure monitoring (external ventricular drain or fiberoptic intraparenchymal monitor) for at least 4 days who were treated with hypertonic saline infusion for elevated intracranial pressure and did not meet exclusion criteria.
INTERVENTION: Continuous hypertonic saline infusion on a sliding scale was used to achieve target sodium levels that would keep intracranial pressure less than 20 mm Hg once the conventional therapies failed.
MEASUREMENTS AND MAIN RESULTS: Eighty-eight children met inclusion criteria. Etiologies of elevated intracranial pressure included trauma (n = 48), ischemic or hemorrhagic stroke (n = 20), infection (n = 8), acute disseminated encephalomyelitis (n = 5), neoplasm (n = 2), and others (n = 5). The mean peak serum sodium was 171.3 mEq/L (range, 150-202). The mean Glasgow Outcome Score was 2.8 (± 1.1) at time of discharge from the hospital. Overall mortality was 15.9%. Children with sustained (> 72 hr) serum sodium levels above 170 mEq/L had a significantly higher occurrence of thrombocytopenia (p < 0.001), renal failure (p < 0.001), neutropenia (p = 0.006), and acute respiratory distress syndrome (p = 0.029) after controlling for variables of age, gender, Pediatric Risk of Mortality score, duration of barbiturate-induced coma, duration of intracranial pressure monitoring, vasopressor requirements, and underlying pathology. Children with sustained serum sodium levels greater than 165 mEq/L had a significantly higher prevalence of anemia (p < 0.001).
CONCLUSIONS: Children treated by continuous hypertonic saline infusion for intracranial hypertension whose serum sodium levels exceeded certain thresholds experienced significantly more events of acute renal failure, thrombocytopenia, neutropenia, anemia, and acute respiratory distress syndrome than those whose sodium level was maintained below these thresholds.

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