Single photon emission computed tomography in patients with acute hydrocephalus or with cerebral ischaemia after subarachnoid haemorrhage

Default Mode Network Perfusion in Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

The etiology of altered consciousness in patients with high-grade aneurysmal subarachnoid hemorrhage (SAH) is not thoroughly understood. We hypothesized that decreased cerebral blood flow (CBF) in brain regions critical to consciousness may contribute.

METHODS

We retrospectively evaluated arterial-spin labeled (ASL) perfusion magnetic resonance imaging (MRI) measurements of CBF in 12 patients with aneurysmal SAH admitted to our neurocritical care unit. CBF values were analyzed within gray matter nodes of the default mode network (DMN), whose functional integrity has been shown to be necessary for consciousness. DMN nodes studied were the bilateral medial prefrontal cortices, thalami, and posterior cingulate cortices. Correlations between nodal CBF and admission Glasgow Coma Scale (GCS) score, admission Hunt and Hess (HH) class, and GCS score at the time of MRI (MRI GCS) were tested.

RESULTS

Spearman's correlation coefficients were not significant when comparing admission GCS, admission HH, and MRI GCS versus nodal CBF (p > 0.05). However, inter-rater reliability for nodal CBF was high (r = 0.71, p = 0.01).

CONCLUSIONS

In this retrospective pilot study, we did not identify significant correlations between CBF and admission GCS, admission HH class, or MRI GCS for any DMN node. Potential explanations for these findings include small sample size, ASL data acquisition at variable times after SAH onset, and CBF analysis in DMN nodes that may not reflect the functional integrity of the entire network. High inter-rater reliability suggests ASL measurements of CBF within DMN nodes are reproducible. Larger prospective studies are needed to elucidate whether decreased cerebral perfusion contributes to altered consciousness in SAH.

Short- and long-term neurobehavioral effects of lumbar puncture and shunting in patients with malabsorptive hydrocephalus after subarachnoid haemorrhage: An explorative case study

BACKGROUND

The neuropsychological effects of lumbar puncture and shunting in terms of cognitive functioning and quality of life were analyzed prospectively in four patients with malabsorptive hydrocephalus who became symptomatic in the chronic state after aneurysmal subarachnoid haemorrhage (SAH).

METHODS

A comprehensive battery of neuropsychological tests was applied to four patients before and shortly after lumbar puncture and six months later. In three of them a shunt has been inserted, one patient was treated by repeated lumbar punctures. In addition, the patients completed a quality of life and a depression questionnaire before lumbar puncture and after shunting. The data were analyzed using single-case methodology.

RESULTS

Hydrocephalus was associated with pronounced cognitive deficits in terms of functions of attention, short- and long-term memory, concentration and motor fine-coordination but not with a general mental deterioration. Quality of life and affect were also substantially impaired. Neuropsychological tests of fronto-cortical cognitive capacity, motor fine coordination and reaction time proved to be sensitive for the short-term effects of lumbar puncture. Memory functions and the capacity of divided attention needed more time for regeneration and improved substantially after shunt implantation.

CONCLUSIONS

We found a complex pattern of cognitive improvement after lumbar puncture and shunting. Furthermore, our results also show a typical cluster of cognitive deficits associated with malabsorptive hydrocephalus including motor dysfunction. These preliminary findings should be confirmed in larger patient samples.

Advanced imaging modalities in the detection of cerebral vasospasm

The pathophysiology of cerebral vasospasm following aneurysmal subarachnoid hemorrhage (SAH) is complex and is not entirely understood. Mechanistic insights have been gained through advances in the capabilities of diagnostic imaging. Core techniques have focused on the assessment of vessel caliber, tissue metabolism, and/or regional perfusion parameters. Advances in imaging have provided clinicians with a multifaceted approach to assist in the detection of cerebral vasospasm and the diagnosis of delayed ischemic neurologic deficits (DIND). However, a single test or algorithm with broad efficacy remains elusive. This paper examines both anatomical and physiological imaging modalities applicable to post-SAH vasospasm and offers a historical background. We consider cerebral blood flow velocities measured by Transcranial Doppler Ultrasonography (TCD). Structural imaging techniques, including catheter-based Digital Subtraction Angiography (DSA), CT Angiography (CTA), and MR Angiography (MRA), are reviewed. We examine physiologic assessment by PET, HMPAO SPECT, ¹³³Xe Clearance, Xenon-Enhanced CT (Xe/CT), Perfusion CT (PCT), and Diffusion-Weighted/MR Perfusion Imaging. Comparative advantages and limitations are discussed.

Aggressive CSF diversion reverses delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage: a case report

BACKGROUND

External ventricular drain (EVD) placement temporarily provides cerebrospinal fluid (CSF) diversion and is indicated in patients with aneurysmal subarachnoid hemorrhage (aSAH) to relieve hydrocephalus.

METHODS

Case report.

RESULTS

A 56-year-old woman was admitted to our hospital with aSAH complicated by acute hydrocephalus. An EVD was placed and set to 15 mmHg. After nearly 72 h, she clinically deteriorated. A computed tomography (CT) perfusion scan showed hypoperfusion in the watershed regions in both hemispheres and CT angiogram showed mild segmental arterial narrowings. After the EVD was lowered to 5 mmHg, the radiologic perfusion abnormalities and clinical symptoms resolved.

CONCLUSIONS

We postulate a mechanism by which CSF diversion could decrease the risk of delayed cerebral ischemia after aSAH: CSF drainage at low levels of intracranial pressure (e.g., 5 mmHg) could improve blood flow in the microcirculation, and thus improve tissue perfusion.

The role of lumbar drainage to prevent shunt-dependent hydrocephalus after coil embolization for aneurysmal subarachnoid hemorrhage in good-grade patients

OBJECTIVE

To evaluate the role of lumbar drainage in the prevention of shunt-dependent hydrocephalus after treatment of ruptured intracranial aneurysms by coil embolization in good-grade patients.

METHODS

One-hundred-thirty consecutive patients with aneurysmal subarachnoid hemorrhage in good-grade patients (Hunt & Hess grades I-III), who were treated by coil embolization between August 2004 and April 2010 were retrospectively evaluated. Poor-grade patients (Hunt & Hess grades IV and V), a history of head trauma preceding the development of headache, negative angiograms, primary subarachnoid hemorrhage (SAH), and loss to follow-up were excluded from the study. We assessed the effects on lumbar drainage on the risk of shunt-dependent hydrocephalus related to coil embolization in patients with ruptured intracranial aneurysms.

RESULTS

One-hundred-twenty-six patients (96.9%) did not develop shunt-dependent hydrocephalus. The 2 patients (1.5%) who developed acute hydrocephalus treated with temporary external ventricular drainage did not require permanent shunt diversion. Overall, 4 patients (3.1%) required permanent shunt diversion; acute hydrocephalus developed in 2 patients (50%). There was no morbidity or mortality amongst the patients who underwent a permanent shunt procedure.

CONCLUSION

Coil embolization of ruptured intracranial aneurysms may be associated with a lower risk for developing shunt-dependent hydrocephalus, possibly by active management of lumbar drainage, which may reflect less damage for cisternal anatomy than surgical clipping. Coil embolization might have an effect the long-term outcome and decision-making for ruptured intracranial aneurysms.

Acute hydrocephalus and cerebral perfusion after aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Acute hydrocephalus after aneurysmal subarachnoid hemorrhage (SAH) may decrease cerebral perfusion by increasing intracranial pressure. We studied cerebral perfusion in patients with and without acute hydrocephalus after SAH.

MATERIALS AND METHODS

We performed noncontrast CT scans, CT perfusion (CTP), and CT angiography on admission in all patients with aneurysmal SAH. Patients were dichotomized at a relative bicaudate index of 1 for the presence or absence of hydrocephalus. Cerebral perfusion was measured in the cortex, basal ganglia, and periventricular white matter. Mean CTP parameters were compared between patients with and without acute hydrocephalus (ie, within 3 days after SAH).

RESULTS

We included 138 consecutive patients with successful CTP measurements, of whom 49 (36%) had acute hydrocephalus. Mean cerebral blood flow (CBF) was lower in patients with hydrocephalus than in those without in the basal ganglia (difference of means, 6.8; 95% CI, 1.6-11.0 mL/100 g/min) and periventricular white matter (difference of means, 3.8; 95% CI, 0.9-6.8 mL/100 g/min) but not in the cortex (difference of means, 1.8; 95% CI, -2.8 to 6.4 mL/100 g/min). In all regions studied, mean transit time (MTT) and time-to-peak (TTP) were statistically significantly longer in patients with hydrocephalus, but cerebral blood volume (CBV) values were similar.

CONCLUSIONS

Acute hydrocephalus after SAH reduces CBF in the deep gray matter and periventricular white matter and delays MTT and TTP in all investigated brain areas. The negative effect of acute hydrocephalus on cerebral perfusion in patients with SAH seems more pronounced in the vicinity of the ventricles than in remote sites.

Changes in cerebral perfusion hormone profile and cerebrospinal fluid flow across the third ventriculostomy after endoscopic third ventriculostomy in patients with aqueductal stenosis: a prospective study. Clinical article

OBJECT

The object of the present study was 3-fold: 1) to study regional cerebral perfusion before and after endoscopic third ventriculostomy (ETV) in patients with obstructive hydrocephalus by using (99m)Tc ethyl cysteinate dimer SPECT: 2) to study any correlation between clinically successful third ventriculostomy and CSF flow across the third ventriculostomy; and 3) to determine any changes in hormone profile following ETV.

METHODS

The authors prospectively studied 15 patients with aqueductal stenosis who underwent ETV during the last 2 years. All the patients underwent pre- and postoperative MR imaging, brain (99m)Tc ethyl cysteinate dimer SPECT, and hormone profile studies.

RESULTS

Eight patients were infants. The mean follow-up duration was 17.6 months. Thirteen patients (86.7%) exhibited clinical improvement after surgery. In all patients with clinical improvement the studies documented CSF flow through the ventriculostomy site. Clinical progress could be correlated with SPECT changes in 14 cases (93.3%). In the 13 clinically successful cases, 12 were substantiated by improvement on SPECT scans, whereas in the 2 failed cases, SPECT images revealed no improvement of perfusion defects. Hormone analysis conducted in 14 patients revealed hyperprolactinemia in 8, low triiodothyronine values in 2 patients, and hypocortisolemia in 1, which was reversed after ETV.

CONCLUSIONS

Clinical improvement is not well correlated with a decrease in ventricular size following ETV. Brain SPECT is a valuable tool for the follow-up of patients with hydrocephalus after ETV, particularly in cases in which MR imaging findings are not clear. There are subtle hormonal changes in patients with hydrocephalus that may improve following ETV.

A near infrared spectroscopy study investigating oxygen utilisation in hydrocephalic rats

Determination of hydrocephalus and its severity is important for optimal management of the condition. We have used near infrared spectroscopy (NIRS) to assess changes in concentrations of oxygenated (O2Hb), deoxygenated (HHb), total haemoglobin (tHb) and cytochrome c oxidase (Caa3) in normal and hydrocephalic Texas (HTx) rats in response to a 5 min head down tilt and a sodium pentobarbitone (NaPB) challenge. The former was used to test vascular responses and the latter to test metabolic responses. The haemoglobin oxygenation index (HbD) was derived which provides information regarding oxygen utilisation ([HbD]=[O2Hb]-[HHb]). With the tilt challenge, a significant (P=0.001) difference was observed in [HbD] between normal (n=24) and hydrocephalic (n=14) rats (-3.50 (-6.00 to 0.00) microM cm(-1 )and 7.50 (0.75 to 14.25) microM cm(-1), respectively). In another experiment we tested the response of ten rats to NaPB administration and observed a significant difference (P=0.008) in [Caa3] between normal (n=5) and hydrocephalic (n=5) rats (-6.60 (-7.55 to -5.50) microM cm(-1 )and -2.20 (-5.60 to -1.05) microM cm(-1), respectively). Coronal sections of these ten rat brains were analysed and significant (P<0.05) relationships were found between some of the NIRS parameters and cortical thickness or lateral ventricle area measurements. Our studies demonstrate that a significant difference in cerebral oxygenation and haemodynamics can be observed between normal and hydrocephalic HTx rats using NIRS.

Does cerebral perfusion improve following CSF diversion in pediatric hydrocephalus? A prospective study using 99mTc ECD single photon emission computed tomography

AIMS AND OBJECTIVES

To study regional cerebral perfusion before and after ventriculoperitoneal shunt placement in children with hydrocephalus, using (99m)Tc ECD single photon emission computed tomography (SPECT).

MATERIALS AND METHODS

17 consecutive children (less than 16 years) with hydrocephalus due to various causes, who were planned for ventriculoperitoneal shunt, were included in this prospective study. Brain SPECT using (99m)Tc ECD was performed pre- and postoperatively and changes in cerebral perfusion were compared with the change in ventricular size (assessed using Evan's ratio).

OBSERVATIONS

There were 11 males and 6 females with a median age of 24 months. Nine children were up to 2 years of age and the mean duration of symptoms was 6 months. The cause of hydrocephalus was congenital in 10, secondary to tumor in 5 and as sequelae of infection in 2 children. Fourteen children (82%) showed improvement in cerebral perfusion following shunting. Of these, 12 also had a concomitant decrease in ventricular size postoperatively.

RESULTS

On logistic regression analysis, none of the factors analyzed, i.e. age, duration of symptoms, etiology of hydrocephalus and decrease in ventricular size, were found to predict improvement of cerebral perfusion following shunting.

CONCLUSIONS

Cerebral perfusion improves in the majority of the children following CSF diversionary procedures, and contrary to the common belief, duration of hydrocephalus and decreased ventricular size do not influence this improvement in cerebral perfusion. SPECT can therefore prove to be a valuable tool for objective assessment of improvement in cerebral perfusion in children with hydrocephalus secondary to various etiologies following surgical or medical interventions.

Perfusion-weighted Magnetic Resonance Imaging in Patients with Vasospasm: A Useful New Tool in the Management of Patients with Subarachnoid Hemorrhage

OBJECTIVE:

Cerebral vasospasm (VSP) is one of the most important risk factors for the development of a delayed neurological deficit after subarachnoid hemorrhage (SAH). Perfusion-weighted magnetic resonance imaging (pwMRI) provides the possibility of detecting tissue at risk for infarction. The objective of our study was to evaluate the feasibility and impact of pwMRI in the management of SAH patients.

METHODS:

From a consecutive series of 180 patients experiencing SAH and treated at our institution over a 3-year period, we identified 20 who underwent pwMRI during their acute illness. For these 20 patients, the results of pwMRI were compared with the results of diffusion-weighted MRI, transcranial Doppler sonography, and neurological examinations performed at the same time and with repeated pwMRI examinations of the same patient at different times.

RESULTS:

Nineteen of 20 patients showed perfusion changes predominantly in the time maps. Fifteen of 19 patients with changes in pwMRI had a neurological deficit at the same time. In 7 of 15 patients with neurological deterioration, transcranial Doppler sonography showed signs of VSP, whereas all 15 patients showed alterations in pwMRI. The areas of perfusion changes in pwMRI correlated well with the neurological deficits of the patients and were larger than the areas of changed diffusion in diffusion-weighted MRI performed at the same time. There were no clinical complications with regard to the pwMRI examinations.

CONCLUSION:

pwMRI is safe and helpful in the management of patients with VSP after SAH. The sensitivity of pwMRI is higher than that of transcranial Doppler sonography in the detection of decreased perfusion as a result of VSP. pwMRI can detect tissue at risk before definitive infarction occurs and therefore may lead to a change of therapy in those patients.

Fenestration of the Lamina Terminalis as a Valuable Adjunct in Aneurysm Surgery

OBJECTIVE:

Hydrocephalus, vasospasm, and frontobasal injury are common complications after aneurysmal subarachnoid hemorrhage (SAH) from anterior communicating artery aneurysms. Previous studies have suggested that fenestration of the lamina terminalis (FLT) during surgery may be associated with reduced rates of shunt-dependent hydrocephalus and vasospasm. We report 106 patients affected by anterior communicating artery aneurysms and Fisher Grade 3 aneurysmal SAH and the affect of FLT on shunt-dependent hydrocephalus, vasospasm, and frontobasal injury.

METHODS:

During a 3-year period, 53 patients underwent FLT and 53 did not. We prospectively evaluated admission and discharge clinical grades, hydrocephalus at admission, occurrence of clinical vasospasm, need for interventional vasospasm therapy, frontobasal hypodensity incidence, and permanent ventriculoperitoneal shunting requirement. Follow-up ranged from 3 to 35 months (mean, 17.9 mo).

RESULTS:

Shunting incidence after aneurysmal SAH with hydrocephalus was 4.25% in patients who underwent FLT and 13.9% in patients who did not (P&lt; 0.001). Clinical cerebral vasospasm occurred in 29.6% of patients who underwent FLT and in 54.7% of patients who did not (P&lt; 0.001). Frontobasal hypodensity was identified postoperatively in 0% of patients who underwent FLT and in 5% of patients who did not. Good outcome was reported in 69.81% of patients who underwent FLT and in 33.96% of patients who did not (P&lt; 0.001). Poor outcome was associated with higher Hunt and Hess grades, need for ventricular drainage, elevated intracranial pressure, and multiple interventional vasospasm therapies. No complications were linked to FLT.

CONCLUSION:

FLT was associated with statistically significant decreases in shunting rates, incidence of vasospasm, and better outcomes. We recommend its routine use in patients with Fisher Grade 3 anterior communicating artery aneurysmal SAH.

Cortical blood flow during cerebral vasospasm after aneurysmal subarachnoid hemorrhage: three-dimensional N-isopropyl-p-[(123)I]iodoamphetamine single photon emission CT findings

BACKGROUND AND PURPOSE

The relationship between regional cerebral blood flow (rCBF) during cerebral vasospasm after subarachnoid hemorrhage (SAH) and angiographic vasospasm and the value of rCBF in predicting vasospasm and the prognosis are not fully delineated. Our aim was to investigate the changes in extent of vasospasm-induced decreased cortical rCBF on three-dimensional (3D) displays of single photon emission CT (SPECT) findings. The clinical usefulness of these assessments was analyzed.

METHODS

In 58 cases of SAH, SPECT and digital subtraction angiography were performed on the same day, 5-9 days after SAH or within 24 hours after the onset of delayed ischemic neurologic deficit (DIND). Cerebral blood flow data were assessed by measuring the area of decreased cortical rCBF on 3D SPECT images.

RESULTS

The area of decreased cortical rCBF on the 3D images was significantly increased in cases with DIND (P <.001), in cases with a large infarction due to vasospasm (P =.006), and in cases with a poor prognosis after vasospasm (P =.045). These increases were also related to the type of angiographic vasospasm; the greatest decrease in cortical rCBF occurred in the combined type (combination of the peripheral and proximal types) of vasospasm, followed by cases with the peripheral type, proximal type, and no angiographic vasospasm. In cases with DIND, patchy decreased cortical rCBF areas were seen before the onset of DIND.

CONCLUSION

Combined-type vasospasm leads to reductions in CBF greater than those due to isolated peripheral or proximal vasospasm. Two-dimensional and mean-hemispheric CBF analyses are less sensitive for this change than is 3D SPECT.

Imaging of haemorrhagic stroke

Computed tomography (CT) is the reference standard for the imaging of acute non-traumatic intracranial haemorrhage. The sensitivity with which CT detects haemorrhage falls with time and lumber puncture remains mandatory for the exclusion of subarachnoid haemorrhage (SAH). Magnetic resonance (MR) imaging is, however, superior to CT in the subacute and chronic stages after haemorrhage. MR in addition offers pathophysiological information that can help with assessment of both the aetiology of and complications arising from both SAH and intra-parenchymal haemorrhage.

Multimodality MR imaging depiction of hemodynamic changes and cerebral ischemia in subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Subarachnoid hemorrhage (SAH) is a common and serious neurologic emergent condition. We tested the hypothesis that multimodality MR imaging depicts changes in cerebral blood flow SAH, before any surgical or endovascular intervention, and that the frequency of these changes increases with time after ictus.

METHODS

We prospectively examined 37 patients with suspected SAH and three with symptoms of acute stroke but who subsequently had SAH. Routine CT and multimodality MR imaging were performed within 18 h of presentation. Standard MR imaging, diffusion-weighted MR imaging, time-of-flight MR angiography, and dynamic first-pass gadolinium-enhanced MR perfusion imaging were performed. Images were reviewed for abnormalities in cerebral blood flow, ischemia, and infarction. Nine patients did not have SAH at CT and CSF investigations. Of 31 patients with proved SAH, 13 were examined during the acute stage (within 4 d of ictus) and 18, during the subacute stage (4-14 d after ictus).

RESULTS

MR imaging showed alteration in cerebral blood flow parameters in 16 of 31 patients before surgery or endovascular treatment. The frequency of blood flow changes and associated complications increased with worsening clinical grade and increasing time after ictus.

CONCLUSION

Multimodality MR imaging provides information not available from CT in patients with SAH. MR imaging shows oligemic and ischemic areas in SAH before surgery or endovascular treatment. MR imaging is a simple noninvasive method of assessing cerebral blood flow and its complications in SAH. It can be performed in a clinical environment.

Diffusion- and perfusion-weighted imaging in vasospasm after subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Better measures of cerebral tissue perfusion and earlier detection of ischemic injury are needed to guide therapy in subarachnoid hemorrhage (SAH) patients with vasospasm. We sought to identify tissue ischemia and early ischemic injury with combined diffusion-weighted (DW) and hemodynamically weighted (HW) MRI in patients with vasospasm after SAH.

METHODS

Combined DW and HW imaging was used to study 6 patients with clinical and angiographic vasospasm, 1 patient without clinical signs of vasospasm but with severe angiographic vasospasm, and 1 patient without angiographic spasm. Analysis of the passage of an intravenous contrast bolus through brain was used to construct multislice maps of relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), and tissue mean transit time (tMTT). We hypothesize that large HW imaging (HWI) abnormalities would be present in treated patients at the time they develop neurological deficit due to vasospasm without matching DW imaging (DWI) abnormalities.

RESULTS

Small, sometimes multiple, ischemic lesions on DWI were seen encircled by a large area of decreased rCBF and increased tMTT in all patients with symptomatic vasospasm. Decreases in rCBV were not prominent. MRI hemodynamic abnormalities occurred in regions supplied by vessels with angiographic vasospasm or in their watershed territories. All patients with neurological deficit showed an area of abnormal tMTT much larger than the area of DWI abnormality. MRI images were normal in the asymptomatic patient with angiographic vasospasm and the patient with normal angiogram and no clinical signs of vasospasm.

CONCLUSIONS

We conclude that DW/HW MRI in symptomatic vasospasm can detect widespread changes in tissue hemodynamics that encircle early foci of ischemic injury. With additional study, the technique could become a useful tool in the clinical management of patients with SAH.

Posthemorrhagic hydrocephalus and brain injury in the preterm infant: dilemmas in diagnosis and management

Advances in neonatal critical care have reduced the incidence of intraventricular hemorrhage (IVH) in the newborn. Paradoxically, however, the prevalence of the complications of IVH including posthemorrhagic hydrocephalus (PHHC) has increased. By virtue of its association with long-term neurodevelopmental disability, posthemorrhagic hydrocephalus is an ominous diagnosis in the premature infant. Animal models have demonstrated that ventricular distention may cause direct cerebral parenchymal injury. Evidence for secondary parenchymal injury in the premature infant with PHHC is by necessity indirect. The precise impact of secondary parenchymal injury on the overall neurological outcome of premature infants with PHHC remains unclear in large part because of the vulnerability of the immature brain to other forms of injury (e.g., periventricular leukomalacia) that may be difficult to distinguish from injury due to distention. Furthermore, parenchymal injury due to PVL may cause ventricular enlargement that does not benefit from CSF diversion. Because these primary and secondary mechanisms of injury may operate concurrently, the precise or dominant cause of ventricular enlargement is often difficult to establish with certainty in the neonatal period. These diagnostic dilemmas have in turn impeded the development and evaluation of therapies specifically aimed at reversing ventricular distention and preventing secondary parenchymal injury. This article focuses on the current dilemmas in diagnosis and management of this potentially reversible form of injury as well as on potential future strategies for its prevention.

Reduced local cerebral blood flow in periventricular white matter in experimental neonatal hydrocephalus-restoration with CSF shunting

The extent to which the reduction in CBF occurring in hydrocephalus is a primary or secondary event in the pathogenesis of the brain injury that ensues has not been clearly established. This is particularly true in neonatal hydrocephalus, where the disorder is most common, and where timing of the treatment of the developing nervous system is so important. We investigated the changes in local CBF (lCBF) in an animal model of severe progressive neonatal hydrocephalus before and after CSF shunting. Hydrocephalus was induced in 27 1-week-old kittens by percutaneous injection of 0.05 ml of 25% kaolin into the cisterna magna. Fourteen littermates acted as controls. The lCBF was measured by 14C-iodoantipyrine quantitative autoradiography after 1 week in 15 animals (8 hydrocephalic, 7 controls) and after 3 weeks in 26 animals (19 hydrocephalic, 7 controls) following induction of hydrocephalus. Twelve of the 3-week hydrocephalic group received a ventriculoperitoneal shunt 10 days following kaolin injection. At 1 week following induction of hydrocephalus, lCBF was globally reduced in cortical gray matter and white matter as well as deep subcortical structures. The maximum reduction was in the parietal white matter, to 37% of control levels. At 3 weeks a significant reduction in lCBF persisted only in the white matter (parietal, occipital, and corpus callosum; average, 42% of control levels), whereas cortical gray and deep subcortical structures had returned to normal levels spontaneously.(ABSTRACT TRUNCATED AT 250 WORDS)

Xenon CT measurement of cerebral blood flow in hydrocephalus

Since the recognition of normal-pressure hydrocephalus as an entity (1965), ventriculo-atrial or peritoneal shunting has been proposed as a treatment for this disease. Unfortunately, selection of patients who would benefit from shunting has always been difficult, and no clinical or brain imaging criteria have been entirely satisfactory. Functional studies intended to measure the local cerebral blood flow (lCBF) seem more promising. Xenon CT CBF measurement has been chosen because of its ability to measure deep white matter lCBF with good spatial resolution. This preliminary study reports the results of lCBF measurement in four patients examined by this technique before and after shunting or cerebrospinal fluid subtraction by lumbar puncture. In this small collective the two patients who improved clinically after shunting or lumbar puncture also had a substantial improvement in deep white matter lCBF.

Our policy in diagnosis and treatment of hydrocephalus

The authors present the policy they have worked out for hydrocephalus patients with special reference to the pressure measurement and test methods and to rCBF, SPECT and transcranial Doppler sonography (TDC) studies. For diagnosis, the protocol proposed by Gjerris and Borgesen was followed in 75 cases: besides other methods (CT, radionuclide cisternography, MRI) the intracranial pressure waves routinely recorded and analyzed by means of ventricular catheters for 24 h. The patients were roughly divided into groups in terms of diagnosis, baseline pressure, compliance, results of infusion tests and of surgery. In 13 patients the investigations were supplemented by rCBF SPECT and in 42 patients by TCD studies before and after CSF shunting or withdrawal to analyze the acute effects on cerebral circulation. Clinical follow-up shows that need for shunting was indicated fairly well by the common results of baseline ICP, compliance and infusion loading. The rCBF SPECT studies revealed a significant increase of the cerebral perfusion at the basal ganglia after shunting while, on the basis of CBF velocity changes three types of vasoregulatory response could be defined with TCD. In our hands, monitoring of the pressure and craniospinal capacity has proved to be a valuable aid in decisions on surgery; however, for a more precise (and beneficial) appreciation of whether surgery is indicated the vasoregulatory responses should also be taken into account in future.

Evaluation of cerebral vasospasm in patients with subarachnoid hemorrhage using single photon emission computed tomography

Cerebral vasospasm (CVS) occurs as a result of the breakdown in cerebral autoregulation mechanisms. Because cerebral vasospasm can occur after subarachnoid hemorrhage (SAH), it is important to evaluate borderline perfusion. Evaluation of borderline vascular insufficiency is important to reduce ischemic complications. In this study 25 patients with SAH were investigated by somatosensory evoked potentials (SEP), computed tomography (CT), digital subtraction angiography (DSA) and single photon emission computed tomography (SPECT) in order to predict borderline ischemic areas. Clinical grades were also correlated with these investigations. Thirteen patients had symptomatic vasospasm and 15 patients had angiographic vasospasm. SPECT showed hypoperfusion in 22 out of 25 patients. CT predicted CVS in 8 of these 22 patients. Our study shows that brain perfusion SPECT is a non-traumatic, non-invasive, non-allergic, inexpensive method for the prediction of cerebral vasospasm. We conclude that brain SPECT with Tc-99m HM-PAO is an accessible technique that can demonstrate varying degrees of regional tissue hypoperfusion in patients with delayed ischemic deficits due to CVS following SAH.

Assessment of cerebral perfusion with single-photon emission tomography in normal subjects and in patients with Alzheimer's disease: effects of region of interest selection

The shape, size and location of regions of interest (ROIs) show considerable variability between single-photon emission tomography (SPET) studies in aging and Alzheimer's disease, but the possible influence on study results remains unknown. We compared three different ROIs in a SPET study with 60 controls and in 48 patients with probable Alzheimer's disease diagnosed according to the NINCDS-ADRDA criteria. Regional cerebral blood flow (rCBF) was assessed with SPET using technetium-99m d,l-hexamethylpropylene amine oxime (99mTc-HMPAO), normalized to the mean activity in a cerebellar reference slice. The three different ROIs were: a multi-slice and a single-slice ROI with reference to the normal brain anatomy (using an anatomical atlas), and a rectangular (2 x 4 pixels) ROI in the frontal, temporal, temporoparietal and occipital cortices. No differences were observed for the means of rCBF values between the single-slice and multi-slice ROI's with reference to the normal anatomy, but some variability was present for individual comparisons. In contrast, significantly higher mean rCBF values were obtained with the single-slice rectangular ROIs in all four regions for both patients and controls and considerable variability was shown for individual subjects. After analysis with multivariate logistic regression and receiver operator characteristic curves, the ability of SPET to discriminate between controls and Alzheimer patients was similar in the three methods for mild and moderate Alzheimer patients (Global Deterioration Scale = GDS of 3 and 4). However, with increasing dementia severity (GDS > 4) the rectangular ROIs showed lower ability to discriminate between groups compared to the single-slice and multi-slice anatomically defined ROIs.(ABSTRACT TRUNCATED AT 250 WORDS)

Shunting in chronic post-traumatic hydrocephalus: demonstration of neurophysiologic improvement

The neuronal metabolic state that forms the cellular basis for cognitive functioning and motor behavior is dependent on cerebral perfusion. As intracerebral pressure increases, cerebral perfusion is compromised. The management of acute hydrocephalus after head trauma has been extensively described. In this article, we present evidence of clinical, cerebral perfusion, and neurophysiologic improvement in a 19-year-old patient with chronic post-traumatic hydrocephalus. Lethargy, gaze palsy, torticollis, and triplegia were noted 2 years postinjury in a neurologically stable patient. Computed axial tomography (CAT) scan confirmed marked enlargement of the third and fourth ventricles with a prominent subgaleal fluid collection. Intraoperative cerebral spinal fluid pressure was 26cm H2O despite hyperventilation. A ventriculo-peritoneal shunt was placed. Postoperatively, marked improvement in clinical exam, cerebral perfusion (SPECT scan), and evoked potentials correlated with the reemergence of the cerebral mantle on CAT scan and magnetic resonance imaging (MRI). Chronic obstructive hydrocephalus should be suspected and aggressively pursued in chronic head injury.

Successful prevention of neurological deficit in SAH patients with 2-chlorodeoxyadenosine

Twenty patients suffering from subarachnoid haemorrhage due to ruptured intracranial aneurysm and operated on within 72 h after SAH were treated with an experimental immunosuppressive drug 2-chlorodeoxyadenosine (2-CDA), dose 0.05 mg/kg/day i.v. for 7 days. The 2-CDA treatment was started immediately after angiographic confirmation of ruptured aneurysm, and the standard pharmacological treatment (nimodipine and steroids) was also given. 50% of patients were severely threatened by "delayed vasospasm" or late neurological deficit (Fisher's score 3 or 4). The neurological outcome (assessed 8-12 weeks after SAH) was good (GOS = 1) in 70%, and fair (moderate disability, GOS = 2) in 25%. A single case of severe disability (GOS = 3), as well as two cases of less than perfect outcome (GOS = 2), were related to unusual pre- or intraoperative complications. We conclude that the low doses of 2-CDA can be considered as a valuable adjunct to the standard pharmacotherapy of SAH patients operated on early.

Distribution of cisternal blood in patients with acute hydrocephalus after subarachnoid hemorrhage

The distribution of cisternal blood in relation to the development of acute hydrocephalus was studied in 246 consecutive patients with aneurysmal subarachnoid hemorrhage who were admitted within 72 hours. Patients with evidence on the initial computed tomograph (CT) of subarachnoid hemorrhage caused by other than a ruptured aneurysm and patients with a negative angiography were excluded. Acute hydrocephalus (defined as a bicaudate index, measured on the initial CT or on a repeat CT within 1 week after subarachnoid hemorrhage, exceeding the 95th percentile for age) was found on the initial CT in 50 (20%) of the 246 patients and on a repeat CT in 9 other patients. Ventricular blood was found significantly more often in patients with acute hydrocephalus than in those in whom acute hydrocephalus did not develop (28 of 59 [47%] versus 58 of 187 [31%]; chi 2 = 4.634, p = 0.031). When the analysis was restricted to the 86 patients with ventricular blood, no significant differences were found in the total amount of cisternal blood and in the distribution of cisternal blood between patients with and without hydrocephalus. In contrast, among the 160 patients without ventricular blood, hydrocephalus was associated with a slightly higher total amount of cisternal blood (Wilcoxon's rank sum test, p = 0.023), and significantly more patients with acute hydrocephalus had a higher score in both ambient cisterns than patients without acute hydrocephalus (20 of 31 [65%] versus 41 of 129 [32%]; chi 2 = 10.007, p = 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)