Jh. Lee et al., HEMODYNAMICALLY SIGNIFICANT CEREBRAL VASOSPASM AND OUTCOME AFTER HEAD-INJURY - A PROSPECTIVE-STUDY, Journal of neurosurgery, 87(2), 1997, pp. 221-233
The authors prospectively investigated cerebral hemodynamic changes in
152 patients with head injuries to clarify the relationship between c
erebral vasospasm and outcome. They also sought to determine the most
clinically meaningful criteria for diagnosing cerebral vasospasm. Pati
ents with varying degrees of moderate-to-severe head injury were monit
ored using transcranial Doppler (TCD) ultrasonography and intravenous
Xe-133-cerebral blood flow (CBF) measurements. Outcome was determined
at 6 months. Using TCD ultrasonography, mean flow Velocities were dete
rmined for the middle cerebral artery (V-MCA, 149 patients) and basila
r artery (V-BA, 126 patients). Recordings of the mean extracranial int
ernal carotid artery Velocity (VEC-ICA) were also performed to determi
ne the hemispheric ratio (V-MCA/VBC-ICA 147 patients). Cerebral blood
flow measurements were obtained in 91 patients. Concurrent TCD and CBF
data from 85 patients were used to calculate a ''spasm index'' (the V
-MCA or V-BA respectively, divided by the hemispheric or global CBF).
The authors investigated the clinical significance of elevated flow ve
locity, hemispheric ratio, and spasm index. Patients diagnosed as havi
ng MCA or BA vasospasm on the basis of TCD-derived criteria alone had
a significantly worse outcome than patients without vasospasm. When CB
F was considered hemodynamically significant vasospasm, as defined by
an elevated spasm index, was even more strongly associated with poor o
utcome. Stepwise logistic regression analysis confirmed that hemodynam
ically significant vasospasm was a significant predictor of poor outco
me, independent of the effects of admission Glasgow Coma Scale score a
nd age. On the basis of the results of this study, the authors suggest
that the important factor impacting on outcome is not vasospasm per s
e, but hemodynamically significant vasospasm with low CBF. These findi
ngs show that Vasospasm is a pathophysiologically important posttrauma
tic secondary insult, which is best diagnosed by the combined use of T
CD and CBF measurements.