Mahmoud Messerer

Cerebral Extracellular Lactate Increase is Predominantly Nonischemic in Patients with Severe Traumatic Brain Injury

Growing evidence suggests that endogenous lactate is an important substrate for neurons. This study aimed to examine cerebral lactate metabolism and its relationship with brain perfusion in patients with severe traumatic brain injury (TBI). A prospective cohort of 24 patients with severe TBI monitored with cerebral microdialysis (CMD) and brain tissue oxygen tension (PbtO2) was studied. Brain lactate metabolism was assessed by quantification of elevated CMD lactate samples (>4 mmol/L); these were matched to CMD pyruvate and PbtO2 values and dichotomized as glycolytic (CMD pyruvate > 119 μmol/L vs. low pyruvate) and hypoxic (PbtO2 < 20 mm Hg vs. nonhypoxic). Using perfusion computed tomography (CT), brain perfusion was categorized as oligemic, normal, or hyperemic, and was compared with CMD and PbtO2 data. Samples with elevated CMD lactate were frequently observed (41 ±8%), and we found that brain lactate elevations were predominantly associated with glycolysis and normal PbtO2 (73 ± 8%) rather than brain hypoxia (14 ±6%). Furthermore, glycolytic lactate was always associated with normal or hyperemic brain perfusion, whereas all episodes with hypoxic lactate were associated with diffuse oligemia. Our findings suggest predominant nonischemic cerebral extracellular lactate release after TBI and support the concept that lactate may be used as an energy substrate by the injured human brain.

Individual patient data systematic review and meta-analysis of optic nerve sheath diameter ultrasonography for detecting raised intracranial pressure: protocol of the ONSD research group

BackgroundThe purpose of the optic nerve sheath diameter (ONSD) research group project is to establish an individual patient-level database from high quality studies of ONSD ultrasonography for the detection of raised intracranial pressure (ICP), and to perform a systematic review and an individual patient data meta-analysis (IPDMA), which will provide a cutoff value to help physicians making decisions and encourage further research. Previous meta-analyses were able to assess the diagnostic accuracy of ONSD ultrasonography in detecting raised ICP but failed to determine a precise cutoff value. Thus, the ONSD research group was founded to synthesize data from several recent studies on the subject and to provide evidence on the diagnostic accuracy of ONSD ultrasonography in detecting raised ICP.MethodsThis IPDMA will be conducted in different phases. First, we will systematically search for eligible studies. To be eligible, studies must have compared ONSD ultrasonography to invasive intracranial devices, the current reference standard for diagnosing raised ICP. Subsequently, we will assess the quality of studies included based on the QUADAS-2 tool, and then collect and validate individual patient data. The objectives of the primary analyses will be to assess the diagnostic accuracy of ONSD ultrasonography and to determine a precise cutoff value for detecting raised ICP. Secondly, we will construct a logistic regression model to assess whether patient and study characteristics influence diagnostic accuracy.DiscussionWe believe that this IPD MA will provide the most reliable basis for the assessment of diagnostic accuracy of ONSD ultrasonography for detecting raised ICP and to provide a cutoff value. We also hope that the creation of the ONSD research group will encourage further study.Systematic review registrationPROSPERO registration number: CRD42012003072

To Look Beyond Vasospasm in Aneurysmal Subarachnoid Haemorrhage

Delayed cerebral vasospasm has classically been considered the most important and treatable cause of mortality and morbidity in patients with aneurysmal subarachnoid hemorrhage (aSAH). Secondary ischemia (or delayed ischemic neurological deficit, DIND) has been shown to be the leading determinant of poor clinical outcome in patients with aSAH surviving the early phase and cerebral vasospasm has been attributed to being primarily responsible. Recently, various clinical trials aimed at treating vasospasm have produced disappointing results. DIND seems to have a multifactorial etiology and vasospasm may simply represent one contributing factor and not the major determinant. Increasing evidence shows that a series of early secondary cerebral insults may occur following aneurysm rupture (the so-called early brain injury). This further aggravates the initial insult and actually determines the functional outcome. A better understanding of these mechanisms and their prevention in the very early phase is needed to improve the prognosis. The aim of this review is to summarize the existing literature on this topic and so to illustrate how the presence of cerebral vasospasm may not necessarily be a prerequisite for DIND development. The various factors determining DIND that worsen functional outcome and prognosis are then discussed.

Percutaneous biopsy of lesions in the cavernous sinus region through the foramen ovale: diagnostic accuracy and limits in 50 patients

OBJECT The cavernous sinus and surrounding regions-specifically the Meckel cave, posterior sector of the cavernous sinus itself, and the upper part of the petroclival region-are the location of a large variety of lesions that require individual consideration regarding treatment strategy. These regions may be reached for biopsy by a percutaneous needle inserted through the foramen ovale. The aim of this retrospective study was to evaluate the diagnostic accuracy of percutaneous biopsy in a consecutive series of 50 patients referred for surgery between 1991 and 2010. METHODS Seven biopsies (14%) were unproductive and 43 (86%) were productive, among which 28 lesions subsequently underwent histopathological examination during a second (open) surgery. To evaluate the diagnostic accuracy of the procedure, results from surgery were compared with those from the biopsy. RESULTS Sensitivity of the percutaneous biopsy was 0.83 (95% CI 0.52-0.98), specificity was 1 (95% CI 0.79-1), and κ coefficient was 0.81. CONCLUSIONS Because of its valuable diagnostic accuracy, percutaneous biopsy of the cavernous sinus and surrounding regions should be performed in patients with parasellar masses when neuroimaging does not provide sufficient information of a histopathological nature. This procedure would enable patients to obtain the most appropriate therapy, such as resective surgery, corticosteroids, chemotherapy, radiotherapy, or radiosurgery.

Transoral Protrusion of a Peritoneal Catheter: A Rare Complication of Ventriculoperitoneal Shunt

Ventriculoperitoneal (VP) shunt surgery is the most used technique for the treatment of hydrocephalus. This procedure is associated with a large amount of complications. Bowel perforation caused by a peritoneal shunt catheter is one of these complications, sometimes fatal, and is usually difficult to recognize, except when protrusion of the peritoneal catheter through a natural orifice occurs. This report presents the case of a 2-year-old boy who had undergone a VP shunt and later presented with protrusion of the peritoneal catheter through his mouth. The shunt device was removed and an external shunt procedure was achieved, using the original ventricular catheter kept in place. The diagnosis of bacterial meningitis was retained and an antibiotic therapy was started. The evolution was fatal in 15 days secondary to a bacterial ventriculitis. Through the reported cases of bowel perforation, many risk factors were individualized, such as age, congenital etiology of the hydrocephalus, silicon allergy or the length of the peritoneal catheter. Bowel perforation is a serious complication of VP shunt surgery, leading sometimes to a fatal outcome.

Spinal epidural hematoma: not always an obvious diagnosis

Spinal epidural hematoma (SEH) is a rare neurosurgical emergency. SEH is characterized by an archetypal clinical presentation including abrupt spinal pain followed more or less rapidly by various degrees of neurological deficit. The diagnosis of SEH, often based on a clinical presumption, represents a clinical challenge. Several reports have outlined missed or delayed diagnosis due to unusual and confusing onsets or unawareness of this diagnosis by physicians. Therefore, physicians should keep in mind the possibility of SEH in their differential diagnosis when confronted with patients complaining of sudden onset of acute spinal pain with or without neurological sign, because the impact of a delayed diagnosis can be disabling catastrophic neurological sequelae. We suggest that SEH is a dynamic disease, which occurs in patients with an abnormal vasculature structural degenerative change. The bleeding is probably of multifactorial origin incriminating veins as well as arteries. Therefore, we proposed a classification of SEH, according to the most probable etiology whatever the associated factors, in six groups: spontaneous, secondary, iatrogenic, traumatic, recurrent, and idiopathic SEH.

Sports-related chronic repetitive head trauma as a cause of pituitary dysfunction.

Traumatic brain injury (TBI) is recognized as a cause of hypopituitarism even after mild TBI. Although over the past decade, a growing body of research has detailed neuroendocrine changes induced by TBI, the mechanisms and risk factors responsible for this pituitary dysfunction are still unclear. Around the world, sports-especially combative sports-are very popular. However, sports are not generally considered as a cause of TBI in most epidemiological studies, and the link between sports-related head trauma and hypopituitarism has not been investigated until recently. Thus, there is a paucity of data regarding this important concern. Because of the large number of young sports participants with near-normal life expectancy, the implications of undiagnosed or untreated postconcussion pituitary dysfunction can be dramatic. Understanding the pathophysiological mechanisms and risk factors of hypopituitarism caused by sports injuries is thus an important issue that concerns both medical staff and sponsors of sports. The aim of this paper was to summarize the best evidence for understanding the pathophysiological mechanisms and to discuss the current data and recommendations on sports-related head trauma as a cause of hypopituitarism.

The Endoscopic Endonasal Approach to the Meckel's Cave Tumors: Surgical Technique and Indications

Many benign and malignant tumors as well as other inflammatory or vascular diseases may be located in the areas of Meckels cave or the cavernous sinus. Except for typical features such as for meningiomas, imaging may not by itself be sufficient to choose the best therapeutic option. Thus, even though modern therapy (chemotherapy, radiotherapy, or radiosurgery) dramatically reduces the field of surgery in this challenging location, there is still some place for surgical biopsy or tumor removal in selected cases. Until recently, the microscopic subtemporal extradural approach with or without orbitozygomatic removal was classically used to approach Meckels cave but with a non-negligible morbidity. Percutaneous biopsy using the Hartel technique has been developed for biopsy of such tumors but may fail in the case of firm tumors, and additionally it is not appropriate for anterior parasellar tumors. With the development of endoscopy, the endonasal route now represents an interesting alternative approach to Meckels cave as well as the cavernous sinus. Through our experience, we describe the modus operandi and discuss what should be the appropriate indication of the use of the endonasal endoscopic approach for Meckels cave disease in the armamentarium of the skull base surgeon.

Occam's razor in minimally invasive pituitary surgery: tailoring the endoscopic endonasal uninostril trans-sphenoidal approach to sella turcica

BackgroundSince the introduction of the endoscopic endonasal approaches in the field of skull base surgery during the last two decades, several variants of the sella turcica endoscopic surgery have been described. The aim of this study is to provide a stepwise description of one of these variants in a minimally invasive/maximally efficient perspective.MethodFor the majority of our sella turcica pathologies, we have progressively adopted a uninostril endoscopic approach that is very conservative towards the nasal mucosa with a very limited mucosal incision, resection of the vomer and allowing an almost ad integrum sellar floor reconstruction, without compromising the efficacy and completeness of both surgical oncologic and endocrine targets.ConclusionThe uninostril trans-sphenoidal endoscopic endonasal approach to sella turcica is tailored to ally maximal efficiency and minimal invasiveness.

Hearing Loss Attributable to a Cerebellopontine-Angle Arachnoid Cyst in a Child

Although hearing loss in newborns and infants is predominantly due to malformations and infections, there are other situations which may compromise hearing quality in later stages, including posterior-fossa arachnoid cysts (ACs). We report the case of an 8-year-old girl who presented with hearing loss linked to a pontocerebellar-angle AC which had been diagnosed and treated when she was 14 months old. The pathophysiology of this late AC complication is discussed. This case reminds us that a close follow-up with audiologic monitoring and/or brain stem auditory evoked response is necessary in children with posterior-fossa AC because modern neuroradiological imaging methods do not inform about cerebral and nerve functions, although they provide excellent morphological details of ACs and have improved the ease and accuracy of their early diagnosis. Therefore, surgery should be performed before complete hearing loss occurs; however, in hearing-impaired patients, it remains unclear which surgical treatment is most appropriate.