Regional cerebral blood flow in patients with hypertensive intracerebral hemorrhage

Persistent Metabolic Disturbance in the Perihemorrhagic Zone Despite a Normalized Cerebral Blood Flow Following Surgery for Intracerebral Hemorrhage

BACKGROUND

We hypothesized that reduced cerebral blood flow (CBF) and/or energy metabolic disturbances exist in the tissue surrounding a surgically evacuated intracerebral hemorrhage (ICH). If present, such CBF and/or metabolic impairments may contribute to ongoing tissue injury and the modest clinical efficacy of ICH surgery.

OBJECTIVE

To conduct an observational study of CBF and the energy metabolic state in the perihemorrhagic zone (PHZ) tissue and in seemingly normal cortex (SNX) by microdialysis (MD) following surgical ICH evacuation.

METHODS

We evaluated 12 patients (median age 64; range 26-71 yr) for changes in CBF and energy metabolism following surgical ICH evacuation using Xenon-enhanced computed tomography (n = 10) or computed tomography perfusion (n = 2) for CBF and dual MD catheters, placed in the PHZ and the SNX at ICH surgery.

RESULTS

CBF was evaluated at a mean of 21 and 58 h postsurgery. In the hemisphere ipsilateral to the ICH, CBF improved between the investigations (36.6 ± 20 vs 40.6 ± 20 mL/100 g/min; P < .05). In total, 1026 MD samples were analyzed for energy metabolic alterations including glucose and the lactate/pyruvate ratio (LPR). The LPR was persistently elevated in the PHZ compared to the SNX region (P < .05). LPR elevations in the PHZ were predominately type II (pyruvate normal-high; indicating mitochondrial dysfunction) as opposed to type I (pyruvate low; indicating ischemia) at 4 to 48 h (70% vs 30%) and at 49 to 84 h (79% vs 21%; P < .05) postsurgery.

CONCLUSION

Despite normalization of CBF following ICH evacuation, an energy metabolic disturbance suggestive of mitochondrial dysfunction persists in the perihemorrhagic zone.

Cerebral blood flow changes associated with intracerebral hemorrhage

Recent advances have furthered our understanding of changes in CBF after ICH. Recent evidence from experimental and clinical studies has not supported the role of CBF changes in the pathogenesis of neuronal injury. A better understanding of these changes in ICH has modified the basis for formulating treatment strategies and developing innovative therapies.

Therapeutic effects of a calcium antagonist, lacidipine, on stroke-prone spontaneously hypertensive rats with cerebrovascular lesions

The aim of this study was to investigate the therapeutic effectiveness of lacidipine in stroke-prone spontaneously hypertensive rat (SHRSP) with cerebrovascular lesions in comparison with nicardipine. SHRSP were fed 1% saline as drinking water. After the onset of stroke, saline was replaced with water and each drug was administered orally once a day for 3 weeks. In the drug-untreated group, recurrence of stroke was repeated, deterioration and amelioration of neurological deficits (ND) were repeated, and histological examination and measurement of regional blood flow (rBF) using nonradioactive colored microspheres performed at the end of treatment revealed severe damages and significantly decreased rBF in brain and kidney, respectively. In kidney, not only lacidipine (1 mg/kg) but also nicardipine (30 mg/kg) decreased vascular lesions and ameliorated low-rBF significantly. Both drugs also inhibited the recurrence of stroke completely even at a low dose that did not ameliorate severe hypertension. Neuronal damages and ND in each lacidipine-treated group were ameliorated significantly, whereas those in each nicardipine-treated group were slightly improved. Lacidipine at 1 mg/kg alone ameliorated the cerebral low-rBF significantly even at 24 hr after administration. These results suggest that a long-lasting improvement of low-rBF after stroke may be useful in the treatment of SHRSP with cerebrovascular lesions.

Pharmacologic reduction of mean arterial pressure does not adversely affect regional cerebral blood flow and intracranial pressure in experimental intracerebral hemorrhage

OBJECTIVE

To determine the effect of mean arterial pressure (MAP) reduction on regional cerebral blood flow and intracranial pressure (ICP) in intracerebral hemorrhage. We tested the hypothesis that there is ischemia in the perihematoma region after intracerebral hemorrhage, which can be exacerbated by a pharmacologic reduction of MAP.

DESIGN

Prospective, controlled, laboratory trial.

SETTING

Animal research laboratory.

SUBJECTS

Eighteen mongrel dogs, weighing 15 to 25 kg.

INTERVENTIONS

We introduced intracerebral hemorrhage in 12 anesthetized dogs by autologous blood injection under arterial pressure in the deep white matter adjacent to the left caudate region. We measured serial regional cerebral blood flow using radiolabeled microspheres in animals with two different volumes of injected blood (2.8 mL [Group A, n = 6] and 4.4 mL [Group B, n = 6]) and compared them with control animals (n = 6). Intravenous labetalol was administered 90 mins after administration of hematoma, while maintaining cerebral perfusion pressure >65 mm Hg. Regional cerebral blood flow measurements were repeated 10 and 30 mins after labetalol administration. MAP and ICP were monitored continuously using intra-arterial and cisterna magna catheters, respectively.

MEASUREMENTS AND MAIN RESULTS

Compared with control animals, significant elevation in ICP was observed in Groups A and B and elevation in MAP was observed in Group B at 45 mins after injection of blood. These hemodynamic alterations were not accompanied by any significant differences in regional cerebral blood flow in any group. Administration of labetalol resulted in a decrease in MAP (mm Hg+/-SEM) in Groups A (119.0+/-9.2 to 103.0+/-9.1) and B (124.5+/-7.4 to 100.5+/-4.8) and controls (103.5+/-4.3 to 85.0+/-8.0). No differences were observed in regional cerebral blood flow after MAP reduction in both Groups A and B compared with controls in regions around or distant to the hematoma. There were no changes in ICP in Groups A and B both at 10 and 30 mins after reduction in MAP compared with pretreatment values.

CONCLUSIONS

In our model, pharmacologic reduction of MAP within the normal autoregulatory limits of cerebral perfusion pressure, 90 mins after onset, had no adverse effect on ICP and regional cerebral blood flow in regions around or distant to the hematoma. These results support the controlled use of antihypertensive treatment in intracerebral hemorrhage in the initial time period.

Treatment of elevated intracranial pressure in experimental intracerebral hemorrhage: comparison between mannitol and hypertonic saline

OBJECTIVE

Elevated intracranial pressure (ICP) is related to mortality after intracerebral hemorrhage (ICH). To develop effective strategies for the medical treatment of ICP in cases of ICH, we evaluated the therapeutic efficacy of mannitol and hypertonic saline in a canine model of ICH.

METHODS

We introduced ICH in three groups of anesthetized mongrel dogs, consisting of seven animals each, by autologous blood injection (5.5-7.5 ml) under arterial pressure in the deep white matter adjacent to the left basal ganglia. We evaluated the effect of iso-osmolar doses (5.5 mOsm/kg) of intravenously administered mannitol (1 gm/kg), 3% NaCl (5.3 ml/kg), or 23.4% NaCl (0.7 ml/kg) administered 2 hours after the introduction of hematoma, on the following: ICP, cerebral perfusion pressure, cerebral oxygen extraction and oxygen consumption, and regional cerebral blood flow in regions around and distant to the hematoma. All measurements were recorded at baseline, before treatment, and 15, 30, 60, and 120 minutes after treatment. We also evaluated the water content (wet/dry weight) and blood-brain barrier permeability (Evans blue method) in pathologically demarcated regions of brain.

RESULTS

There was an immediate reduction in ICP (mm Hg +/- standard error of the mean) in the 23.4% NaCl (27.6+/-4 to 11.0+/-2 mm Hg, P = 0.001), 3% NaCl (23.7+/-3 to 14.7+/-2 mm Hg, P = 0.009), and mannitol (25.6+/-3 to 15.9+/-4 mm Hg, P = 0.02) groups. Compared with pretreatment values, ICP was significantly lower in both the 23.4% NaCl (12.3+/-2 mm Hg, P = 0.002) and 3% NaCl (17.6+/-2 mm Hg, P = 0.008) groups but not in the mannitol group (18.7+/-4 mm Hg, P = 0.08) 15 minutes after the administration of treatment. There was a gradual rise in ICP observed in the 23.4% NaCl and mannitol groups with time. Only in the 3% NaCl group was the ICP significantly lower than the pretreatment value at 120 minutes (18.0+/-2 mm Hg, P = 0.02). A significantly higher cerebral perfusion pressure (108.4+/-4 versus 79.6+/-10 mm Hg, P = 0.048) and lower water content in the lesioned white matter (65.5+/-1% versus 67.9+/-1%, P = 0.07) was observed 2 hours after treatment in animals receiving 3% NaCl compared with animals receiving mannitol. There were no significant differences observed in regional cerebral blood flow, oxygen extraction, or oxygen consumption at any time point among the three groups.

CONCLUSION

Hypertonic saline, in both 3 and 23.4% concentrations, is as effective as mannitol in the treatment of intracranial hypertension observed in association with ICH. Hypertonic saline may have a longer duration of action, particularly when used in 3% solution. None of three treatment regimens influence regional cerebral blood flow or cerebral metabolism.

Hemodynamics of hypertensive putaminal hemorrhage evaluated by Xenon-enhanced computed tomography and acetazolamide test

Cerebral blood flow (CBF) is usually decreased in patients with hypertensive putaminal hemorrhage (HPH). However, there are few reports concerning cerebrovascular reserve capacity (CRC) in these cases. This study evaluated cerebral hemodynamics in patients with HPH by measuring CBF and CRC. CBF and CRC were measured by stable xenon enhanced computed tomography (Xe-CT) in 11 patients with HPH (HPH group) and 11 patients with essential hypertension without intracerebral hematoma (non-HPH group). CBFs of the hemisphere and thalamus in the HPH group were lower than those in the non-HPH group. And the CBF of the hemisphere was increased transiently after the surgical evacuation of the hematoma. Thereafter, it fell gradually. The CRCs were also lower in acute stage of the HPH group. The CRC recovered during the chronic stage. Hemodynamics in patients with HPH can be modulated by surgical removal of hematoma. However, some adjunct therapies are necessary to prevent delayed neuronal inactivity, Stable Xe-CT with acetazolamide test is useful to evaluate hemodynamics in the HPH patients.

Improvement of cerebral blood flow following stereotactic surgery in patients with putaminal haemorrhage

Changes in cerebral blood flow (CBF) after CT guided stereotactic aspiration of putaminal haematoma were investigated in 13 patients with Xe-133 inhalation and single photon emission computed tomography. The interval from onset to operation ranged from 13 to 82 days (mean 30 days). The mean estimated haematoma volume ranged from 20 to 50 ml (mean 31.9 ml). The percentage of haematoma aspirated ranged from 75 to 98% (mean 86.8%). Postoperative CBF in two thirds of the patients was improved even though all cases were operated on in the subacute stage. Both the mean hemispheric and regional CBF in the anterior territory of the middle cerebral artery and in the region of the thalamus and basal ganglia in the affected hemisphere were increased postoperatively. Also in the nonaffected hemisphere, regional CBF in the region of the thalamus and basal ganglia was improved.

Unilateral spatial neglect due to hemorrhage in the thalamic region

In a series of 33 cases of thalamic hemorrhage, unilateral spatial neglect (USN) was found in 11 patients all of whom had right-sided lesions. An analysis of results suggests that the posteromedial portion of the thalamus plays an important role in the pathogenesis of USN and that extensive lesions beyond the thalamus involving nearby structures may be necessary to cause persistent USN.