Elevated Intracranial Pressure

MRI findings of elevated intracranial pressure in cerebral venous thrombosis versus idiopathic intracranial hypertension with transverse sinus stenosis

Authors: Ridha MA, Saindane AM, Bruce BB, Riggeal BD, Kelly LP, Newman NJ, Biousse V.

PURPOSE: To determine whether MRI signs suggesting elevated intracranial pressure (ICP) are preferentially found in patients with idiopathic intracranial hypertension (IIH) than in those with cerebral venous thrombosis (CVT).
METHODS: Among 240 patients who underwent standardized contrast-enhanced brain MRI/MRV at our institution between 9/2009 and 9/2011, 60 with abnormal imaging findings on MRV were included: 27 patients with definite IIH, 2 patients with presumed IIH, and 31 with definite CVT. Medical records were reviewed, and imaging studies were prospectively evaluated by the same neuroradiologist to assess for presence or absence of transverse sinus stenosis (TSS), site of CVT if present, posterior globe flattening, optic nerve sheath dilation/tortuosity, and the size/appearance of the sella turcica.
RESULTS: 29 IIH patients (28 women, 19 black, median-age 28, median-body mass index, 34) had bilateral TSS. 31 CVT patients (19 women, 13 black, median-age 46, median-BMI 29) had thrombosis of the sagittal (3), sigmoid (3), cavernous (1), unilateral transverse (7), or multiple (16) sinuses or cortical veins (1). Empty/partially-empty sellae were more common in IIH (3/29 and 24/29) than in CVT patients (1/31 and 19/31) (p<0.001). Flattening of the globes and dilation/tortuosity of the optic nerve sheaths were more common in IIH (20/29 and 18/29) than in CVT patients (13/31 and 5/31) (p<0.04).
CONCLUSION: Although abnormal imaging findings suggestive of raised ICP are more common in IIH, they are not specific for IIH and are found in patients with raised ICP from other causes such as CVT.

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.

Measuring Elevated Intracranial Pressure through Noninvasive Methods: A Review of the Literature

Authors: Kristiansson H, Nissborg E, Bartek J Jr, Andresen M, Reinstrup P, Romner B.

Elevated intracranial pressure (ICP) is an important cause of secondary brain injury, and a measurement of ICP is often of crucial value in neurosurgical and neurological patients. The gold standard for ICP monitoring is through an intraventricular catheter, but this invasive technique is associated with certain risks. Intraparenchymal ICP monitoring methods are considered to be a safer alternative but can, in certain conditions, be imprecise due to zero drift and still require an invasive procedure. An accurate noninvasive method to measure elevated ICP would therefore be desirable. This article is a review of the current literature on noninvasive methods for measuring and evaluating elevated ICP. The main focus is on studies that compare noninvasively measured ICP with invasively measured ICP. The aim is to provide an overview of the current state of the most common noninvasive techniques available. Several methods for noninvasive measuring of elevated ICP have been proposed: radiologic methods including computed tomography and magnetic resonance imaging, transcranial Doppler, electroencephalography power spectrum analysis, and the audiological and ophthalmological techniques. The noninvasive methods have many advantages, but remain less accurate compared with the invasive techniques. None of the noninvasive techniques available today are suitable for continuous monitoring, and they cannot be used as a substitute for invasive monitoring. They can, however, provide a reliable measurement of the ICP and be useful as screening methods in select patients, especially when invasive monitoring is contraindicated or unavailable.

Treatment of Elevated Intracranial Pressure with Hyperosmolar Therapy in Patients with Renal Failure

Authors: Hirsch KG, Spock T, Koenig MA, Geocadin RG.

BACKGROUND: To evaluate the use of hyperosmolar therapy in the management of elevated intracranial pressure (ICP) and transtentorial herniation (TTH) in patients with renal failure and supratentorial lesions.
METHODS: Patients with renal failure undergoing renal replacement therapy treated with 23.4% saline (30-60 mL) and/or mannitol for high ICP or clinical evidence of TTH were analyzed in a retrospective cohort.
RESULTS: The primary outcome measure was reversal of TTH or ICP crisis. Secondary outcome measures were modified Rankin scale on hospital discharge, survival to hospital discharge, and adverse effects. Of 254 subjects over 7 years, 6 patients with end-stage renal disease had 11 events. All patients received a 23.4% saline bolus, along with mannitol (91%), hypertonic saline (HS) maintenance fluids (82%), and surgical interventions (n = 2). Reversal occurred in 6/11 events (55%); 2 of 6 patients survived to discharge. ICP recording of 6 TTH events showed a reduction from ICP of 41 ± 3.8 mmHg (mean ± SEM) with TTH to 20.8 ± 3.9 mmHg (p = 0.05) 1 h after the 23.4% saline bolus. Serum sodium increased from 141.4 to 151.1 mmol/L 24 h after 23.4% saline bolus (p = 0.001). No patients were undergoing hemodialysis at the time of the event. There were no cases of pulmonary edema, clinical volume overload, or arrhythmia after HS.
CONCLUSIONS: Treatment with hyperosmolar therapy, primarily 23.4% saline solution, was associated with clinical reversal of TTH and reduction in ICP and had few adverse effects in this cohort. Hyperosmolar therapy may be safe and effective in patients with renal failure and these initial findings should be validated in a prospective study.

Influence of the Individual Dpoae Growth Behavior on Dpoae Level Variations Caused by Conductive Hearing Loss and Elevated Intracranial Pressure

Authors: Deppe C, Kummer P, Gürkov R, Olzowy B.

OBJECTIVES: Minor conductive hearing loss (CHL) can compromise the evaluation of the inner ear function with distortion product otoacoustic emissions (DPOAE). Elevation of the intracranial pressure (ICP) is also expected to alter the middle ear (ME) sound transmission. An impaired ME sound transmission leads to an attenuation of the DPOAE primary tone levels (L1 and L2) during forward transmission and of DPOAE levels (LDP) during backward transmission. The effect of the attenuation of L1 and L2 is complex and might have unexpected effects on DPOAE levels. In this work, CHL- and ICP-induced alterations of LDP versus L1 growth functions (constant L2 and increasing L1) are investigated. The first aim of this study is to explain how alterations of ME sound transmission can affect DPOAEs and to characterize the dependency of DPOAE level alterations on L2,L1 combinations and on the individual shape of LDP versus L1 growth functions. The second aim is to identify analogies between CHL- and ICP-induced alterations of DPOAEs and to discuss implications for a potential noninvasive ICP monitoring.
DESIGN: This study focuses on general theoretical considerations, supported by selected experimental observations in different species and simulations. DPOAEs were measured in guinea pigs before and after induction of a CHL (1 ear) and during increased ICP (1 ear), and in humans during changes of the postural position to alter the ICP (4 ears).
RESULTS: In both CHL and elevated ICP, DPOAE levels are not only reduced, but LDP versus L1 growth functions exhibit a shift to higher L1. The absolute DPOAE level alterations strongly depend on the L2,L1 combinations and the individual shape of the LDP versus L1 growth functions. In steeper LDP versus L1 growth functions, the DPOAE level alterations exhibit a larger variation. DPOAE levels can even increase. The largest variation can be found in ears with a nonmonotonic DPOAE growth behavior. An example of a guinea pig ear is presented with a nonmonotonic DPOAE growth behavior and a CHL of 4 dB, where the DPOAE level alterations varied between -32 and +9 dB depending on L1.
CONCLUSIONS: The data enable a more comprehensive view of DPOAE level alterations during CHL and elevated ICP. The observations also explain the problem that DPOAE and ICP alterations do not correlate linearly. An evaluation of the shift of the LDP versus L1 growth function along the L1 axis provides a potential tool to improve both the assessment of the inner ear function in the presence of a CHL and noninvasive ICP monitoring with DPOAEs.

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