Early changes of brain perfusion after subarachnoid hemorrhage - the effect of sodium nitroprusside.

Causes of early hypoperfusion after subarachnoid hemorrhage (SAH) include intracranial hypertension as well as vasoconstriction. The aim of the study was to assess the effect of intracerebroventricular (ICV) administration of sodium nitroprusside (SNP) on early hypoperfusion after SAH. Male Wistar rats (220-240 g) were used, SAH group received 250 microl of fresh autologous arterial blood into the prechiasmatic cistern; sham-operated animals received 250 microl of isotonic solution. Therapeutic intervention: ICV administration of 10 microg SNP; 5 microl 5 % glucose (SNP vehicle) and untreated control. Brain perfusion and invasive blood pressure were monitored for 30 min during and after induction of SAH. Despite SNP caused increase of perfusion in sham-operated animals, no response was observed in half of SAH animals. The other half developed hypotension accompanied by brain hypoperfusion. There was no difference between brain perfusion in SNP-treated, glucose-treated and untreated SAH animals during the monitored period. We did not observe expected beneficial effect of ICV administration of SNP after SAH. Moreover, half of the SNP-treated animals developed serious hypotension which led to brain hypoperfusion. This is the important finding showing that this is not the option for early management in patient after SAH.

Spontaneous intracranial hypotension-hypovolemia associated with tacrolimus.

There is little precedent for a medication-induced spontaneous intracranial hypotension/cerebrospinal fluid (CSF) hypovolemia (SIH). This case history of a woman with low CSF pressure, orthostatic headache, and radiographic findings consistent with SIH but without a detectable leak was notable for its association, both onset and resolution, with the use of the calcineurin inhibitor tacrolimus (FK506). A literature review for potential causes of a tacrolimus-induced CSF hypotension suggests many potential mechanisms of action, including effects on blood brain barrier and dural compliance, and supports further vigilance for this condition in the medically complex setting of tacrolimus use.

Capecitabine-related intracranial hypotension syndrome mimicking dural metastasis in a breast cancer patient: case report and review of the literature.

Spontaneous intracranial hypotension (SICH) is an entity, which is secondary to iatrogenic manipulation and breaching of dura. Postural headache in patients should be suspected, cranial magnetic resonance imaging (MRI) is essential for precise diagnosis. Hallmark of MRI is regular shape of pachymeningeal gadolinium enhancement and subdural effusion. It may mimic central nervous system (CNS) metastasis. Prevention of such cases from receiving cranial radiotherapy by misinterpretation of the gadolinium enhancement as CNS metastasis is an important issue. Capecitabine is an antineoplastic agent, of which metabolites can cross blood-brain barrier in CNS via epithelial tissue. It may cause decrease in CSF production. SICH might be the clinical reflection of this decrease in CSF production. Review of the English literature revealed limited data because of the very little experience with oncologic patients suffering from intracranial hypotension. We report a case of spontaneous intracranial hypotension during capecitabine treatment. Patient was completely well following drug discontinuation and supportive treatment.

Transient cerebral hypoperfusion enhances intraarterial carmustine deposition into brain tissue.

We hypothesized that bolus injections of lipid soluble chemotherapeutic drugs during transient cerebral hypoperfusion could significantly boost regional drug delivery. In the first two groups of New Zealand White rabbits we measured brain tissue carmustine concentrations after intravenous infusion, intraarterial infusion with normal perfusion, and after intraarterial injections during transient cerebral hypoperfusion. In the third group of animals we assessed the safety of the technique by assessing electroencephalographic changes for 6 h after flow arrest carmustine administration and subsequent histological examination. The brain tissue carmustine concentrations were fivefold to sevenfold higher when the drug was injected during cerebral hypoperfusion compared to a conventional intracarotid infusion (68.4 +/- 24.5 vs. 14.2 +/- 8.3 microg/g, n = 5 each, respectively, P < 0.0001). The brain tissue carmustine concentrations (y) were a linear function of the bolus dose (x) injected during cerebral hypoperfusion, y = 10.4 x x - 21 (R = 0.84, P < 0.001). Stable EEGs were recorded several hours after flow arrest carmustine exposure and histological examinations did not reveal any gross evidence of cerebral injury. Transient cerebral hypoperfusion during intraarterial bolus injection of carmustine significantly increases drug delivery. Clinical techniques that decrease CBF, such as, transient arterial occlusion by balloon tipped catheters, hyperventilation, hypothermia, induced hypotension, or transient circulatory arrest, could enhance intraarterial drug delivery to the brain. We believe that the mechanisms for improved drug delivery is the decrease in drug dilution by reduced or absent blood flow, decreased protein binding and a longer time for high concentrations of free drugs to transit through the blood brain barrier.