Les dangers de l’hypothermie thérapeutique

Therapeutic hypothermia (less than 35 °C) is a promising strategy to improve neuroprotection after severe brain injury. Except in patients resuscitated from cardiac arrest, its effectiveness has not yet been demonstrated. Therapeutic hypothermia results in various side effects, including cardiovascular, hydroelectrolytic and infectious disorders, which could explain, in part, the lack of conclusive clinical studies. These hazards are associated with practical difficulties to induce and maintain targeted hypothermia and with rewarming management. An improvement in the techniques for achieving targeted hypothermia, more knowledge about side effects and further randomized clinical trials are needed before recommending the use of therapeutic hypothermia for patients with severe traumatic brain injury.     

Hypothermie et protection cérébrale après traumatisme crânien. Influence des gaz du sang

The usefulness of therapeutic hypothermia is highly debated after traumatic brain injury. A neuroprotective effect has been demonstrated only in experimental studies: decrease in cerebral metabolism, restoration of ATP level, better control of cerebral edema and cellular effects. Despite negative multicenter clinical studies, therapeutic hypothermia is still used to a better control of intracranial pressure. However, important issues need to be clarified, particularly the level and duration of hypothermia, the depth and modalities of sedation. A clear understanding of blood gases variations induced by hypothermia is needed to understand the cerebral perfusion and oxygenation changes. It is essential to recognize and to use hypothermia-induced physiological hypocapnia and alkalosis under strict control of cerebral oxygen balance (jugular venous saturation or tissue PO₂) and also to take into account the increased affinity of hemoglobin for oxygen. Management of post-traumatic intracranial hypertension using hypothermia, directed by intracranial pressure level, and consequently for long duration, is potentially beneficial but needs further clarification.     

Métabolisme cellulaire,température et agression cérébrale

Brain temperature is strongly linked to brain metabolic rate. In the brain, energy metabolism is mainly oxidative. The oxidative metabolism and heat production are therefore strongly related. In normal conditions, heat production consecutive to brain energy metabolism is counterbalanced by heat loss, by using a complex heat exchange system. After major cerebral injuries as subarachnoid haemorrhage or traumatic brain injury, cerebral temperature can often exceed systemic temperature. Moreover, brain temperature can vary independently to systemic temperature, making difficult the prediction of brain temperature from other central temperatures. Mitochondrial dysfunction is probably the corner stone of these post-injury perturbations of brain temperature. Understanding of this phenomenon remains however not complete.     

Rôle délétère de l’hyperthermie en neuroréanimation

Fever is a secondary brain injury and may worsen neurological prognosis of neurological intensive care unit (NICU) patients. In response to an immunological threat, fever associates various physiological reactions, including hyperthermia. Its definition may vary but the most commonly used threshold is 37.5 °C. In animal studies, hyperthermia applied before, during or after cerebral ischemia may increase the volume of ischemic lesions. The mechanism of this effect may include increase in blood brain barrier permeability, increase in excitatory amino acid release and increase in free radical production. In NICU patients, fever is frequent, occurring in up to 20–30% of patients. Moreover, after haemorrhagic stroke, fever has been reported in 40–50% of patients. In half of the patients, fever may be related to an infectious cause but in more than 25% of patients, hyperthermia may be of central origin. After ischemic stroke, hyperthermia during the first 72 hours is associated with an increase in infarct size and increase in morbidity and mortality. This holds true also after subarachnoid haemorrhage. After traumatic brain injury, fever is not related to mortality but may increase morbidity. Whereas no causal link has been established between fever and unfavourable outcome, it seems reasonable to treat hyperthermia in patients suffering from brain injuries. In such patients, antipyretics have a moderate efficacy. In case of failure, they should be replaced by physical cooling techniques.     

Pulsed transcranial Doppler examination in the acute phase of stroke

INTRODUCTION: Transcranial pulsed Doppler sonography with or without imagery is used in the acute phase of ischemic stroke in order to define stroke mechanism and intracranial hemodynamic consequences. STATE OF ART: This non-invasive low-cost investigation can be undertaken rapidly, within 10 minutes if guided by focal symptomatology. It detects middle cerebral artery stenosis in >or=50 p. cent of cases with a sensitivity between 75 and 90 p. cent, comparatively with conventional angiography, and middle cerebral artery occlusion with 90 p. cent sensitivity. When a temporal acoustic window is lacking, intravenous injection of a contrast agent allows good visualization of the intracranial vessels and the circle of Willis, in two-third of cases. Moreover, transcranial Doppler data have good prognostic value and facilitate analysis of recanalization after thrombolytic therapy. CONCLUSION: Beside its diagnostic and prognostic interest, transcranial Doppler sonography using a 2 MHz frequency appears to have therapeutic impact by favoring the thrombolysis process. Future developments may include early and prolonged insonation of patients suffering from stroke.     

Ureteroplasty by penile pedicular flap

The authors relate a retrospective study on 30 cases of urethral stenosis and four cases of urethral rupture with a mean follow up of 28 months (8 to 44 months). The mean age of the patients was 47.5 years (6 to 85 years). The main aetiology was inflammatory sclerosis (73.5%). The predilection was bulbar (52.94%). The main symptom was constituted by dysuria (n = 24). The peri-urethral sclerosis was found in 44, 12% of cases. The penile flap as tube or patch. Immediate complications were a loosen of sutures (n = 7), urinary fistula (n = 4). The later complications were essentially recidives (n = 6). The results were good in 73.5% of cases.     

Neuroradiological investigations in mild brain injuries: state of the art and practical recommendations

OBJECTIVES: To clarify the contribution of each technique of neuroradiological and nuclear medicine investigations after mild brain injuries. To analyze the pathophysiological mechanisms of the lesions. To update indications for imaging techniques in the short or long term management. To define the practical recommendations. METHOD: The international databases were consulted for each neuroradiological technique; the most valuable articles were retained for study (PubMed, ). RESULTS AND DISCUSSION: Standard skull X-rays are obsolete. Craniofacial (bony windows) and brain CT-scan (parenchymal windows) is the most efficient diagnosis tool in the acute phase because of its accessibility. Brain MRI is less accessible in the emergency setting but is feasible in some centers. It is the best choice in the first weeks following mild brain injury but may be normal. Taking into account the limitations of morphological imaging, functional imaging techniques (SPECT, fMRI, PET-scan) are necessary as they may show axonal damage or brain atrophy. There is however the problem of availability. SPECT is the most accessible. Spectro-MRI is promising. In spite of progress in neuroradiological investigation methods, the neuropsychological evaluation and multi-disciplinary treatment of these patients by a skilled team remains of utmost importance.     

Mild brain injury: forensic sciences and indemnification

Victims of mild trauma brain injury may develop post-concussive symptoms in an inverse proportion to the organic damages leading to difficulties in their social, occupational and family activities. Proving the link which exists between the trauma and its consequences is a difficult task and insufficient methods for evaluating post-concussive symptoms make it very difficult to demonstrate the cause and effect relationship. The judge's assessment is essential to avoid the nearly systematic but wrong diagnosis of pathological predispositions of the patient. It is particularly important to improve the nomenclature of the different kinds of injuries to reach a better indemnification for those patients who suffer from their trauma their entire life.     

Neuropsychology and forensic assessment in brain injured patients

Neuropsychology, which deals with the relationships between upper mental functions and brain structures is directly involved with psychiatric and psychological disorders and thus constitutes one of the major domains of cognitive sciences. The impairment of upper mental functions is evident after severe brain injuries causing significant motor deficits. However, it is becoming increasingly evident that even mild or moderate brain injuries can cause sequelae which are difficult to analyze and quantify clinically. These sequelae constitute an "invisible handicap" which may greatly interfere with the patient's professional, relational and social life. The neuropsychological evaluation must be systematic and complete and has to be carried out with a sufficient hindsight (two to three years after the trauma) using neuropsychological and behavioural deficiency evaluation scales. Psychometric tests are also necessary. The data obtained from this evaluation must be correctly interpreted and constitutes the main exhibit in the forensic examination of the brain injured patient.