E.S. Rabinovich, S.S. Rabinovich, S.V. Astrakov, V.I. Yarokhno
Research Institute of Traumatology and Orthopedics,
Municipal Clinical Hospital N 34, Novosibirsk, Russia
Dislocation syndrome is one of the first manifestations of increasing brain compression. Despite introduction of tomographic methods of examination, determination of dislocation causes is connected with difficulties in many cases. CT- or MRI- examination of patients with artificial respiration is a not an easy process from a technical point of view. Not every hospital has tomographic devices at its disposal and sometimes it is impossible to transport a patient with severe craniocerebral trauma (SCCT). At the same time ascertaining reliable criteria of progressive dislocation conditions tactics and necessity of urgent treatment.
The goal of the present research was to study possibility of diagnosis of brain dislocation with the help of transcranial Doppler (TCD).
Materials and Methods. MultiDop-T DWL apparatus was used for monitoring of 178 patients with SCCT (Glasgow Coma Scale score£8). Successful bilateral insonation of MCA and ICA was carried out in compliance with a conventional method. Systolic, mean and diastolic linear blood flow velocities, pulsation index, cerebrovascular reactivity index and Lindergardt's index were estimated. A carotid artery compression test was used for assessing autoregulation of cerebral blood flow in all cases. The results of this test served the basis for evaluation of overshoot coefficient (OC), autoregulation potential (AP), a period of blood flow restoration.
Results. It is known, that the most frequent cause of brain dislocation is compression by intracranial hematoma. As for our study, it led to autoregulation disorders in 52% of cases (OC<1.28, AP<0.55). A prolonged period of restoration of linear blood flow velocity was watched in 38%. There was direct correlation between autoreguation disorders and a phase of clinical compensation (r=0.8564).
A phase of clinical subcompensaton of impaired cerebral circulation was characterized by a tendency to increase of linear blood flow velocity and prolongation of a period of blood flow restoration after a compression test.
A phase of moderate clinical decompensation was characterized by acceleration of blood flow, a change of a dopplerogram's form with reduction of diastolic velocity, increase of pulsation index. It was indicative of intracranial hypertension. Asymmetry of CO was revealed in 40% of cases. It reflected possibility of a various degree of autoregulation disorders in brain hemispheres. It was found out, that a reduced autoregulation response in hypercapnia was typical of those patients, who had had no autoregulation disorders in this phase under conditions of normocapnia.
There was reduction of linear blood flow velocity in a phase of gross decompensation or during transition of a phase of moderate clinical decompensation into a phase of gross decompensation. A compression test revealed considerable reduction of CO without asymmetry of an autoregulation response. When applied in patients of more than 60 years old, who had brain dislocation on a homolateral side, this test showed either absence of a hyperemic response or a paradoxical response in the form of reduction of postcompression linear blood flow velocity. As for MCA, the latter was more than 10% lower in comparison with its value before compression. An autoregulation response on the contralateral side was well-marked; however, restoration of the initial velocity was delayed (> 8 sec). A compression test, used in hypercapnia, demonstrated a reduced autoregulation response in those patients, who had had no autoregulation disorders under conditions of normocapnia. Dislocation was caused by intracranial hematoma in all the cases. Its presence was verified during interventions.
Conclusion. TCD, used in an acute period of severe craniocerabral trauma, allows to detect early signs of brain dislocation and, thus, to make a more precise choice of treatment tactics.