Search Results

You are looking at 1 - 3 of 3 items for

  • Author or Editor: Helge Nornes x
  • By Author: Grolimund, Peter x
Clear All Modify Search
Restricted access

Karl-Fredrik Lindegaard, Peter Grolimund, Rune Aaslid and Helge Nornes

✓Blood flow velocities in basal cerebral arteries were recorded noninvasively in 28 patients with cerebral arteriovenous malformations (AVM's) and were correlated with the angiographic findings. In normal arteries remote from the AVM, flow velocities ranged from 44 to 94 cm/sec (median 65 cm/sec) with pulsatility indexes from 0.65 to 1.10 (median 0.87). This is consistent with findings in normal individuals. Arteries feeding the AVM's were identified by the high flow velocities (ranging from 75 to 237 cm/sec, median 124 cm/sec). The pulsatility index ranged from 0.22 to 0.74 (median 0.48). The difference of these results from findings in normal remote arteries was highly significant (p < 0.001). Hyperventilation tests illustrated the hemodynamic difference between an AVM and normal cerebrovascular beds.

Flow velocity measurements permitted noninvasive diagnosis of AVM's in 26 of the 28 patients. Furthermore, the identification of individual feeding arteries permitted good definition of the anatomical localization of individual AVM's. Flow velocity measurements combined with computerized tomography scans are useful in the diagnosis of AVM's. With the feeding artery's configuration identified on angiography, flow velocity measurements permit a new insight into the “hemodynamic dimension” of an AVM and its possible effects on adjacent normal brain-tissue perfusion in the individual patient.

Restricted access

Rolf W. Seiler, Peter Grolimund, Rune Aaslid, Peter Huber and Helge Nornes

✓ In 39 patients with a proven subarachnoid hemorrhage (SAH), the clinical status, the amount of subarachnoid blood on a computerized tomography scan obtained within 5 days after SAH, and the flow velocities (FV's) in both middle cerebral arteries (MCA's) measured by transcranial Doppler sonography were recorded daily and correlated. All patients had pathological FV's over 80 cm/sec between Day 4 and Day 10 after SAH. The side of the ruptured aneurysm showed higher FV's than did the unaffected side in cases of laterally localized aneurysms. Increase in FV preceded clinical manifestation of ischemia. A steep early increase of FV's portended severe ischemia and impending infarction. Maximum FV's in the range of 120 to 140 cm/sec were not critical and in no case led to brain infarction. Maximum FV's over 200 cm/sec were associated with a tendency for ischemia, but the patients may remain clinically asymptomatic. In cases of no or only a little blood in the basal cisterns, mean FV's in both MCA's increased only moderately whereas, with thick clots of subarachnoid blood, there was a steeper and higher increase of mean FV's.

Restricted access

Karl-Fredrik Lindegaard, Søren Jacob Bakke, Peter Grolimund, Rune Aaslid, Peter Huber and Helge Nornes

✓ Noninvasive transcranial Doppler recordings were correlated to the angiographic findings in 77 patients with carotid artery disease. Stenoses reducing the luminal area of the internal carotid artery by 75% or more also reduced the pulsatility transmission index (PTI) of the ipsilateral middle cerebral artery (MCA). The PTI is the pulsatility index of the artery under study expressed as a percent of the pulsatility index of another intracranial artery with presumed unimpeded inflow in the same individual. For stenoses in the 75% to 89% category, PTI reduction was significantly greater in patients with bilateral carotid stenosis, indicating an impaired potential for collateral flow in these patients. The PTI reduction probably reflects both the pressure drop across the stenosis and the cerebral autoregulatory response. Two criteria proved useful in demonstrating collateral MCA supply through the circle of Willis. On the recipient side, retrograde flow in the proximal anterior cerebral artery was demonstrated in 29 of the 31 patients when this flow pattern was disclosed angiographically. In 26 of these patients, the anterior cerebral artery on the supplying side also had clearly increased flow velocity. Increased flow velocities in the proximal posterior cerebral artery were present in 26 of the 30 vessels that were acting as a collateral channel to the ipsilateral MCA.