Changes in cerebral blood flow during PaCO2 variations in patients with severe closed head injury: comparison between the Fick and transcranial Doppler methods.

OBJECT: The aim of this study was to reassess whether middle cerebral artery blood flow velocity (MCAv) variations measured by transcranial Doppler ultrasonography during acute PaCO2 manipulation adequately reflect cerebral blood flow (CBF) changes in patients with severe closed head injury. METHODS: The study was performed by comparing MCAv variations to changes in CBF as assessed by measurements of the difference in the arteriovenous content in oxygen (AVDO2). The authors initiated 35 CO2 challenges in 12 patients with severe closed head injury during the acute stage. By simultaneous recording of systemic and cerebral hemodynamic parameters, 105 AVDO2 measurements were obtained. Patients were stratified into two groups, "high" and "low," with respect to whether their resting values of MCAv were greater than 100 cm/second during moderate hyperventilation. Four patients displayed an elevated MCAv, which was related to vasospasm in three cases and to hyperemia in one case. The PaCO2 and intracranial pressure levels were not different between the two groups. The slope of the regression line between 1 divided by the change in (delta)AVDO2 and deltaMCAv was not different from identity in the low group (1/deltaAVDO2 = 1.08 x deltaMCAv - 0.07, r = 0.93, p < 0.001) and significantly differed (p < 0.05) from the slope of the high group (1/deltaAVDO2 = 1.46 x deltaMCAv - 0.4, r = 0.83, p < 0.001). CONCLUSIONS: In patients with severe closed head injury, MCAv variations adequately reflect CBF changes as assessed by AVDO2 measurements in the absence of a baseline increase in MCAv. These observations indicate that both moderate variations in PaCO2 and variations in cerebral perfusion pressure do not act noticeably on the diameter of the MCA. The divergence from the expected relationship in the high group seems to be due to the heterogeneity of CO2-induced changes in cerebrovascular resistance between differing arterial territories.

Shunt failure in adult hydrocephalus: flow-controlled shunt versus differential pressure shunts--a cooperative study in 289 patients.

BACKGROUND: In order to assess the efficiency of flow-controlled shunts in reducing shunt failure in the treatment of adult hydrocephalus (with a special focus on overdrainage complications), a series of 289 patients was analyzed through a retrospective and comparative study performed in three neurosurgical departments. METHODS: A group of 142 adult patients suffering from hydrocephalus were operated on using a conventional differential pressure (DP) shunt and compared with a group of 147 adult patients operated on using flow-controlled (FC) system (Orbis-Sigma, Cordis). Only the first complication, which required a surgical revision within the first 2 years after shunt implantation, was taken into account for each patient and analyzed using life-table methods. RESULTS: The actuarial risk of shunt infection in the two groups is respectively 8.3% and 10.9% at 1 year (nonsignificant difference). The actuarial risk of mechanical complications at 1 year is 38% for the DP patients and 10% for the FC patients (p = 0.0001); this difference is largely due to a decrease of complications related to overdrainage phenomenon (14/142 subdural collections were observed in the DP group versus 1/147 in the FC group) (p = 0.0001). CONCLUSION: The conclusion of this cooperative and retrospective study is that the use of a flow-controlled system decreases the risk of mechanical complications related to the hydrodynamic properties of the shunts used in the treatment of adult hydrocephalus, especially those related to overdrainage.

[Treatment of chronic hydrocephalus in adults by flow-regulated shunt. Apropos of a series of 46 patients]. / Traitement de l'hydrocéphalie chronique de l'adulte par dérivation à débit régulé. A propos d'une série de 46 patients.

46 patients, 24 males and 22 females (mean age: 68.3 years), with chronic hydrocephalus were operated on by a variable-resistance, flow-regulated shunt. The selecting criteria before surgery were essentially clinical (association of gait disturbances, dementia and urinary incontinence, positive lumbar puncture withdrawal test) in consideration with the retrospective and cooperative study of this series. Hydrocephalus had an etiology in 23 cases (50%): 4 cases of trauma (8%), 9 cases of tumors (20%), 9 cases of subarachnoid haemorrhage (20%) and 1 case of infection (2%). The average follow-up is 17 months (median: 12 months). 20 patients (43.5%) have an excellent result (normal life), 16 patients (34.8%) have a good result (residual symptomatology compatible with a self-governing life), 5 patients (10.9%) have a poor result (residual symptomatology non compatible with a self-governing life), 2 patients (4.3%) have a bad result (unchanged symptomatology). 3 patients died after the surgical procedure. 3 patients had an infectious complication of their shunt (actuarial risk of infectious complication at one year and a half: 7%). 2 patients presented a non infectious complication, one chronic subdural hematoma and one bad insertion of the proximal catheter (actuarial risk of mechanical complication at one year and a half: 4.4%).

[Intracerebral hematoma surgically treated under x-ray computed tomography with Backlund's needle. A series of 15 cases]. / Hématomes intracérébraux opérés sous contrôle scanographique à l'aide du trocart de Backlund. Une série de 15 cas.

15 cases of supratentorial intracerebral hematomas (12 cases of primary hematomas and 3 post-traumatic cases) were operated under C.T. scan control, using the screw and suction technique (Backlund's needle). 10 cases of primary hematomas were operated early, before the 24th hour. The patients were selected for intervention on the following criteria: 1) Patients aged less than 70 years old; 2) initial Glasgow coma scale between 6 and 10; 3) cases with involvement of the mesencephalon by the hematoma were excluded. In the 3 cases of post-traumatic hematomas, intervention was decided in reference to the clinical course. The volume of the hematomas ranged from 40 to 160 cc. Putaminal or thalamic hematomas were observed in 9 cases. The percentage of aspirated hematoma volume ranged from 50 to 91%, the average being 70.5%. Dramatic improvement of the consciousness was observed in all cases. Improvement of the motor deficit was incomplete, for the most part. 1 patient rebled and 1 patient died (6.6% mortality). In 26% of the cases (4 patients) the development of a brain oedema, in the surrounding of the residual hematoma site, was observed during the post operative follow up. There was no post operative infection. Intervention under direct C.T. control allows an accurate guidance of the needle. Efficacity of the evacuation is attested by an immediate improvement of the mass effect on C.T. scan. Under C.T. control the risk to aspirate the adjacent brain is avoided. The technique proposed here has been easily performed in emergency condition.