Intérêt du doppler transcrânien chez les patients suspects de mort cérébrale

Abstract

Transcranial Doppler ultrasonography (TCD) is a non invasive technique which assesses blood flow velocitics in basal cerebral arteries. Specific patterns have been observed in brain death. In a continuous series of 72 patients, the TCD recordings from the intracranial internal carotid and middle cerebral arteries were compared with the results from the usual investigations for brain death, such as electroencephalogramme (EEG), and arteriography. All the patients were clinically brain dead : Glasgow score of 3, apnoea, bilateral mydriasis, loss of cortical function and cerebral reflexes. This clinical diagnosis was confirmed by and isoelectric EEG with or without angiographic circulatory arrest. Two characteristic patterns were identified : an oscillating to and fro signal, with a positive sharp systolic peak and a negative diastolic reflux ; and a systolic peak without any diastolic component. The absence of signal on both sides did not allow any conclusion, except when this pattern occurred during follow-up. The oscillating pattern was seen on both sides in 60 patients (83 %), and, in 3 other patients, only on one side, always combined with a contralateral systolic peak pattern, in 3 other patients. A bilateral systolic peak pattern was identified in 7 patients (10 %). The TCD results were compared with angiography in 37 cases. TCD circulatory arrest preceded angiographic arrest by six hours in three cases. Hypotension was the main limitation to this technique. On the other hand, TCD may be used in patients treated with sedative drugs. The non invasive character of TCD, its low cost, the possibility of repeating it at the patient's bedside make TCD a very interesting diagnostic tool. The specificity and sensitivity of this technique need to be confirmed in larger serics of patients.