Intraoperative intracranial pressure and cerebral perfusion pressure for predicting surgical outcome in severe traumatic brain injury

Authors: Tsai TH, Huang TY, Kung SS, Su YF, Hwang SL, Lieu AS.

Intraoperative intracranial pressure (ICP) and cerebral perfusion pressure (CPP) were evaluated for use as prognostic indicators after surgery for severe traumatic brain injury (TBI), and threshold ICP and CPP values were determined to provide guidelines for patient management. This retrospective study reviewed data for 66 patients (20 females and 46 males) aged 13-83 years (average age, 48 years) who had received decompressive craniectomy and hematoma evacuation for severe TBI. The analysis of clinical characteristics included Glascow Coma Scale score, trauma mechanism, trauma severity, cerebral hemorrhage type, hematoma thickness observed on computed tomography scan, Glasgow Outcome Scale score, and mortality. Patients whose treatment included ICP monitoring had significantly better prognosis (p < 0.001) and significantly lower mortality (p = 0.016) compared to those who did not receive ICP monitoring. At all three major steps of the procedure, i.e., creation of the burr hole, evacuation of the hematoma, and closing of the wound, intraoperative ICP and CPP values significantly differed. The ICP and CPP values were also significantly associated with surgical outcome in the severe TBI patients. Between hematoma evacuation and wound closure, ICP and CPP values differed by 6.8 ± 4.5 and 6.5 ± 4.6 mmHg, respectively (mean difference, 6 mmHg). Intraoperative thresholds were 14 mmHg for ICP and 56mmH for CPP. Monitoring ICP and CPP during surgery improves management of severe TBI patients and provides an early prognostic indicator. During surgery for severe TBI, early detection of increased ICP is also crucial for enabling sufficiently early treatment to improve surgical outcome. However, further study is needed to determine the optimal intraoperative ICP and CPP thresholds before their use as subjective guidelines for managing severe TBI patients.

Deep venous structures distortion in spontaneous intracranial hypotension as an explanation for altered level of consciousness

Authors: Ajlan AM, Al-Jehani H, Torres C, Marcoux J.

Spontaneous intracranial hypotension (SIH) is a syndrome of low pressure headache associated with low CSF pressure. The condition is generally considered benign but extreme cases of SIH can lead to changes in the level of consciousness. We describe a case in which alteration in the level of consciousness was prolonged and severe, and could not be explained solely by the presence of subdural collections. MRI of the brain showed evidence of impaired venous flow secondary to brain sagging causing distortion of deep venous structures.

Effect of mannitol on cerebrovascular pressure reactivity in patients with intracranial hypertension

Authors: Tang SC, Lin RJ, Shieh JS, Wu AY, Lai DM, Huang SJ, Jeng JS.

BACKGROUND: Mannitol is commonly used in patients with increased intracranial pressure (ICP), but its effect on cerebrovascular pressure reactivity (CVPR) is uncertain. We analyzed the changes of pressure reactivity index (PRx) during the course of mannitol treatment.
METHODS: Twenty-one patients who received mannitol treatment for increased ICP were recruited prospectively. Continuous waveforms of arterial blood pressure (ABP) and ICP were collected simultaneously for 60 minutes (10 minutes at baseline and 50 minutes since mannitol administration) during 37 events of mannitol treatment. The correlation coefficients between the mean ABP and ICP were averaged every 10 minutes and labeled as the PRx. The linear correlation of six time points of PRx in each event was calculated to represent the trend of CVPR changes. The negative slope of correlation was defined as improvement in CVPR under mannitol treatment and vice versa.
RESULTS: At baseline, the average of ICP was 26.0 ± 9.1 mmHg and the values of PRx were significantly correlated with ICP (p = 0.0044, r = 0.46). After mannitol administration, the average of ICP decreased significantly to 21.2 ± 11.1 mmHg (p = 0.036), and CVPR improved in 59.4 % of all events. Further analysis showed that low baseline cerebral perfusion pressure was the only hemodynamic parameter significant association with the improvement of CVPR after mannitol treatment (p = 0.039).
CONCLUSION: Despite lowering ICP, mannitol may have diverse effects on CVPR in patients with intracranial hypertension. Our study suggests that mannitol infusion may have a beneficial effect on CVPR, particularly in those with a low cerebral perfusion pressure at baseline.

Idiopathic intracranial hypertension; research progress and emerging themes

Authors: Batra R, Sinclair A.

Idiopathic intracranial hypertension (IIH) is a condition characterised by increased intracranial pressure of unknown cause predominantly seen in obese women of childbearing age and associated with a history of recent weight gain. The aetiology is poorly understood and there are no evidence-based guidelines on the management of the disease. We aim to provide a review of the recent literature outlining the latest advances in this field over the past few years. Areas of emerging interest related to the pathophysiology of IIH will be discussed, such as the role of obesity, adipose tissue and 11β-hydroxysteroid dehydrogenase type 1. We consider the latest research on the role of venous sinus stenosis in IIH and ex vivo advances into cerebrospinal fluid drainage via the arachnoid granulation tissue. The latest techniques for optic nerve head evaluation and the role of optical coherence tomography will be summarised. Finally, we will discuss recent advances in the management of IIH, including weight loss, and medical and surgical treatment strategies.

Pressures, Flow, and Brain Oxygenation During Plateau Waves of Intracranial Pressure

Authors: Dias C, Maia I, Cerejo A, Varsos G, Smielewski P, Paiva JA, Czosnyka M.

BACKGROUND: Plateau waves are common in traumatic brain injury. They constitute abrupt increases of intracranial pressure (ICP) above 40 mmHg associated with a decrease in cerebral perfusion pressure (CPP). The aim of this study was to describe plateau waves characteristics with multimodal brain monitoring in head injured patients admitted in neurocritical care.
METHODS: Prospective observational study in 18 multiple trauma patients with head injury admitted to Neurocritical Care Unit of Hospital Sao Joao in Porto. Multimodal systemic and brain monitoring of primary variables and secondary variables related to cerebral compensatory reserve and cerebrovascular reactivity were supported by dedicated software ICM+ ( www.neurosurg.cam.ac.uk/icmplus) . The compiled data were analyzed in patients who developed plateau waves.
RESULTS: In this study we identified 59 plateau waves that occurred in 44 % of the patients (8/18). During plateau waves CBF, cerebrovascular resistance, CO, and brain tissue oxygenation decreased. The duration and magnitude of plateau waves were greater in patients with working cerebrovascular reactivity. After the end of plateau wave, a hyperemic response was recorded in 64 % of cases with increase in CBF and brain oxygenation. The magnitude of hyperemia was associated with better autoregulation status and low oxygenation levels at baseline.
CONCLUSIONS: Multimodal brain monitoring facilitates identification and understanding of intrinsic vascular brain phenomenon, such as plateau waves, and may help the adequate management of acute head injury at bed side.

Therapeutic Hypothermia With the Use of Intracranial Pressure Monitoring for Acute Disseminated Encephalomyelitis With Brainstem Lesion: A Case Report

Authors: Miyamoto K, Kozu S, Arakawa A, Tsuboi T, Hirao JI, Ono K, Arisaka O.

Acute disseminated encephalomyelitis confined to the brainstem is associated with poor prognosis. We describe a case of a 10-year-old boy with acute disseminated encephalomyelitis in the brainstem that developed after influenza A infection. A 10-year-old boy presented with fever and prolonged disturbance of consciousness and was admitted to our hospital. Magnetic resonance imaging (MRI) of the midbrain, with T2-weighted and fluid-attenuated inversion recovery images, suggested acute disseminated encephalomyelitis accompanied by a brainstem lesion. Lumbar puncture showed pleocytosis and increased protein content, including myelin basic protein, interleukin-6, and immunoglobulin G, all suggestive of acute disseminated encephalomyelitis. Treatments such as methylprednisolone pulse therapy, intravenous immunoglobulin, and therapeutic hypothermia were performed. Although the patient presented with anisocoria with increased intracranial pressure monitoring during hypothermia, prompt therapy with d-mannitol and dopamine was effective. Our case results suggest that hypothermia could be included in the choice of therapy for acute disseminated encephalomyelitis with brainstem lesions.

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