Increased intracranial pressure

Does bilateral transverse cerebral venous sinus stenosis exist in patients without increased intracranial pressure?

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

OBJECTIVE: Transverse cerebral venous sinus stenosis (TSS) is common among patients with idiopathic intracranial hypertension. TSS likely also exists among individuals with normal intracranial pressure (ICP) but the prevalence is unclear. The goal of this study was to identify patients with incidental TSS and normal ICP and describe their characteristics.
METHODS: Among 240 adult patients who underwent brain magnetic resonance imaging (MRI) with magnetic resonance venography (MRV) with contrast at our institution between September 2009 and September 2011, 44 had isolated TSS without further substantial imaging abnormality. Medical records were reviewed for symptoms of increased ICP, papilledema, cerebrospinal fluid (CSF) constituents and opening pressure (OP), and reason for brain imaging. Of these, 37 were excluded for confirmed or possible idiopathic intracranial hypertension. Of the remainder, 5 had CSF-OP ≤25cmH(2)O without papilledema, and 2 did not have measured ICP, but had no papilledema or symptoms of increased ICP. Imaging was re-interpreted to assess for signs suggestive of elevated ICP and to characterize the TSS further.
RESULTS: All patients were women (mean age: 41, mean BMI: 37.1). CSF contents were normal, but OPs were at the upper limit of normal (22-25cmH(2)O). Indications for MRI/MRV included query pituitary abnormality (1), migraine (4), and anomalous-appearing optic nerves (2). All had bilateral TSS. Six had short TSS and an empty sella; 1 had long TSS and no empty sella; 1 had flattening of the posterior sclera; 2 had prominence of peri-optic nerve CSF.
CONCLUSION: Asymptomatic bilateral TSS exists in patients with ICP≤25cmH(2)O, but is likely uncommon. CSF-OP was at the upper limit of normal in our patients, who also had other radiologic signs suggestive (but not specific) of chronically-raised ICP. Findings of bilateral TSS on imaging should prompt funduscopic examination for papilledema.
Copyright © 2012 Elsevier B.V. All rights reserved.

Modified brain stem auditory evoked potentials in patients with intracranial mass lesions

Authors: Stone JL, Fino J, Patel K, Calderon-Arnulphi M, Suss N, Hughes JR.

The authors report their experience utilizing a recently described rapid rate, binaural click and 1000-Hz tone burst modification of the brain stem auditory evoked potentials (BAEP), modified (MBP), in 27 symptomatic patients with non-brain stem compressive space-taking cerebral lesions (22), hydrocephalus (4), and pseudotumor cerebri (1).  Many presented with clinical signs suggestive of increased intracranial pressure (ICP) and focal neurological deficits. The cerebral lesions, mostly large tumors with edema, had very substantial radiological signs of mass effect. Fourteen patients were also studied following surgical decompression. A number of significant changes in the wave V and Vn latency/intensity and less so amplitude/intensity function was found in the 27 patients, compared to normal volunteers, as well as those studied pre- and postoperatively. Similar MBP changes had been noted in normal volunteers placed in a dependent head position. Possible mechanisms to explain these findings are discussed.  The MBP methodology shows promise and further development could make neuro-intensive care unit monitoring practical.

Increased intracranial pressure is associated with the development of acute lung injury following severe traumatic brain injury

Authors: Lou M, Chen X, Wang K, Xue Y, Cui D, Xue F.

OBJECTIVE: This study investigated the relationship among intracranial pressure (ICP), the development of acute lung injury (ALI) and systemic inflammatory response syndrome (SIRS) following a severe traumatic brain injury (TBI).
METHODS: Post-traumatic ICP was continuously monitored for the first week following injury in a series of consecutive patients with isolated severe TBI. The initial ICP and the duration of intracranial hypertension (ICH) were calculated. The risk factors associated with the development of ALI and SIRS were evaluated.
RESULTS: Of the 86 patients enrolled, 22 patients developed ALI and 52 patients developed SIRS during the observation period. The patients with ALI presented with a significantly higher initial ICP (31.3±7.8mmHg vs. 23.0±8.8mmHg, p<0.001) and a longer duration of ICH (16.8±6.5h vs. 11.9±6.0h, p=0.002) than those without ALI. The incidence of both ALI and SIRS increased with increasing initial ICP, and the presence of SIRS was associated with a fourfold increase in the risk of developing ALI (odds ratio , 4.0; 95% confidence interval , 1.2-13.0).
CONCLUSIONS: Increased ICP is associated with increased risks of developing ALI and SIRS following severe TBI. Future studies designed to verify the causative relationship between increased ICP and the systemic responses are warranted.
Copyright © 2012 Elsevier B.V. All rights reserved.

Diagnosing increased intracranial pressure

Authors: Schimpf MM.

Increased intracranial pressure (ICP) is a challenging complication to treat within a critical care setting. It is imperative that clinicians use a stepwise approach in developing a diagnosis, as to be comprehensive and decrease morbidity and mortality related to increased ICP. This article provides an algorithm that can be used as a clinical guideline when assessing a patient who has an ICP monitor in place and is presenting with increased ICP. The algorithm is inclusive and composed of a history of present illness, review of systems, physical assessment, labs, and further testing.

The analysis of allodynia in patients with idiopathic intracranial hypertension

Authors: Ekizoglu E, Baykan B, Orhan EK, Ertas M.

Objectives: Allodynia is frequently associated with migraine and other primary headaches. Our aim was to investigate the presence of allodynia and related features in idiopathic intracranial hypertension (IIH), which is a disabling secondary headache disorder.Methods: We included 46 IIH patients and analyzed their clinical and laboratory findings retrospectively. Allodynia was assessed using the validated 12-item allodynia symptom checklist (ASC-12), in addition to examining pressure (with von Frey filaments) and brush allodynia.Results: Allodynia was detected in 23 (50%) of IIH patients with ASC-12 and/or instrumental testing. The most commonly reported location was unilateral V1 distribution. The allodynic symptom profile was similar but milder when compared to 143 migraineurs with ASC-12. Only the aggravation of headache with physical activity emerged as a significant variable associated with allodynia in IIH. Among allodynic patients, only eight had previous migraine diagnosis. After onset of IIH, 20 patients reported migraine-like headache, while only three reported non-migrainous headache. In contrast, 13 of 23 non-allodynic IIH patients had non-migrainous headache features (p = 0.0045).Conclusion: Half of the IIH patients reported allodynia, and these allodynic patients had mostly migraine-like headache profiles. Our study suggested that IIH may trigger some common mechanisms with migraine in pain pathways causing allodynia.

An unusual cause of visual impairment in tuberculous meningitis

Authors: Malhotra HS, Garg RK, Gupta A, Saxena S, Majumdar A, Jain A.

Impairment of vision is a devastating complication of tuberculous meningitis which may occur as a result of increased intracranial pressure, compression over the visual pathways or vasculitis. We herein present occurrence of neuroretinitis in a 35-year-old lady presenting with low grade fever and headache for one month, and associated with diminution of vision from 3weeks. She was diagnosed as a case of definite tuberculous meningitis and initiated on anti-tuberculous treatment as per WHO guidelines with supplemental corticosteroids. Marked improvement in vision was observed and at 3months of follow-up the patient was asymptomatic. Direct ophthalmoscopy, visual field analysis, fluorescein angiography, optical coherence tomography and magnetic resonance imaging of the brain were done to document the ophthalmological findings. Neuroretinitis, being an unusual cause of visual impairment in tuberculous meningitis, must be considered in patients without any evidence of raised intracranial pressure or compression, and with normal fluorescein angiography. We suggest that neuroretinitis may be added to list of causes of visual impairment in patients with tuberculous meningitis.

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