Value of transcranial doppler ultrasonography compared with scintigraphic techniques and EEG in brain death

Since 1991 transcranial doppler sonography has been accepted in Germany as a technical confirmatory test for the assessment of a cerebral circulatory arrest in patients fulfilling the clinical criteria of brain death. This study correlated transcranial doppler findings to established scintigraphic methods such as planar scintigraphy, 99mTc-HMPAO SPECT and EEG patterns. 21 patients (15 males/6 females, mean age 15-69 yrs.) fulfilled all clinical criteria of brain death. They suffered from head injuries and spontaneous bleedings. All clinical and technical investigations were performed within 60-90 minutes. In 14/21 patients clinical findings and all confirmatory tests were consistent with brain death. Planar scintigraphy and SPECT gave completely corresponding results in all 21 patients. 7 patients showed not corresponding results. In two head-injured patients with skull defects TCD yielded an oscillating flow in the MCA but SPECT/planar scintigraphy gave a residual perfusion in the related brain areas. A corresponding residual EEG pattern was seen in one case. A patient with osteoclastic skull defect showed a collateral flow from the external carotid artery and another case a secondary reperfusion in depth of a regular expected MCA signal 12 hours after definitely verification of systolic spikes in the Circle of Willis. No cerebral perfusion was detectable in the scintigraphique techniques. In the three remainder with rest activity in EEG, TCD and radionuclide methods showed no intracranial perfusion. In the presence of open skull fractures, external liquor drainages and osteoclastic craniotomies oscillating flow in TCD does not constantly represent a cerebral circulatory arrest. Awaiting of systolic spikes is absolutely necessary, if no radionuclide method is available. Determination of brain death by TCD should be carried out by an experienced investigator since unexpected collateral flow signals can be misinterpreted.     

Use of rCBF in diagnosis and follow-up of cerebral vitamin B12 deficiency

Evidence for cerebral B12 deficiency was searched for in 16 patients (age range 54–94 years) with subnormal serum B12 values (<110 pmol/l) with or without anaemia using sequential regional cerebral blood flow measurement (rCBF). Three patterns of responses followed B12 substitution in 11/16 cases: marked increase of the cerebral blood flow after one week (1); complete or partial normalization of regional decreases after one week (2) or after 1–3 months (3). Mental disturbances were observed in 14/16 patients and abnormally slow EEG activity in 11/12 patients before B12 substitution. During substitution a parallel clinical improvement was observed in 5/7 cases, who could cooperate in a follow-up study, and normalization or marked improvement of the abnormal EEG activity was observed in three cases. We propose that rCBF is a valuable tool for diagnosis and follow-up of this deficiency state. In addition, our results indicate that prophylactic B12 substitution should be considered at serum B12 serum values above the lower normal value especially in aged patients with coexisting organic brain disease.     

SPECT imaging of cerebral arteriovenous angiomas. A preliminary report

BACKGROUND AND PURPOSE: The purpose of this study was to demonstrate scintigraphic evaluation of cerebral perfusion in patients with intracranial hemangiomas. MATERIAL AND METHOD: The examination was carried out in 12 patients aged from 12 to 67 years. In all the patients cerebral angiomas were previously diagnosed and all of them were qualified for intravascular embolization. Brain scintigraphy was performed after IV injection of 99mTcECD and included the dynamic phase with images obtained every 2 seconds for 1.5 minutes and SPECT imaging. The semiquantitative analysis of regional cerebral blood flow was based on the comparison between activity in two symmetrical regions of interest. Cerebral angiography combined with intravascular embolization followed the scintigraphic examination. RESULTS: Based on angiograms, the size of the nidus was estimated at 1.0 to 9.0 cm. In 8 patients the dynamic study showed an increased tracer accumulation in the region of angioma. On SPECT images the nidus was visualized as focally decreased perfusion in all cases. A decreased tracer accumulation in the area adjacent to the nidus was detected in 8 patients. The ratio of activity in the region of angioma to activity in normally perfused tissue calculated using the semiquantitative analysis was 52% to 89%. CONCLUSIONS: SPECT images and dynamic phase of cerebral perfusion scintigraphy allow perfusion changes caused by the presence of intracranial angiomas to be identified.     

Contrast-enhanced transcranial color-coded sonography in acute hemispheric brain infarction.

PURPOSE: The aim of the present study was to investigate the diagnostic potential of contrast-enhanced transcranial color-coded real-time sonography (CE-TCCS) in otherwise ultrasound-refractory acute stroke patients with an ischemia in the territory of the middle cerebral artery (MCA). Furthermore, correlations of CE-TCCS findings with clinical, angiographic, and CT results were investigated. METHODS: In 90 acute stroke patients with inadequate insonation conditions in unenhanced transcranial color-coded real-time sonography (TCCS) examinations, CE-TCCS, clinical, angiographic, and CT examinations were performed within 12 hours, 36 hours (CE-TCCS only), and 1 week after onset of clinical symptoms. A CT angiography (CTA) as reference method was available in 39 individuals. After application of a galactose-based echo-enhancing agent, the portion of conclusive ultrasound examinations of the MCA, as manifested by an MCA occlusion, decreased or increased flow velocity (FV), and symmetrical MCA FV, was evaluated. CE-TCCS findings on admission and during follow-up were correlated with infarction size as demonstrated on follow-up CT, and clinical findings were assessed by use of the European Stroke Scale. RESULTS: Adequate diagnosis was achieved in 74 of 90 patients (82%) by the use of echo contrast agents. MCA occlusion or reduction of MCA FV was found in 20 and 27 patients, respectively. MCA occlusion was confirmed by CTA in 17 cases. In one individual, false-positive diagnosis of MCA occlusion was made according to ultrasound criteria. In 5 patients with MCA occlusion, vessel recanalization was observed during follow-up; 15 of 27 patients with decreased flow velocities showed normalization after the third examination that was associated with a significantly better clinical outcome (P<0.0001). Furthermore, MCA occlusion or decreased FV in the first 12 hours were associated with significantly larger infarctions in the MCA territory compared with normal CE-TCCS findings (P<0.0001). CONCLUSIONS: CE-TCCS enables adequate diagnosis in approximately 80% of acute hemispheric stroke patients with insufficient unenhanced TCCS examinations. It is a reliable diagnostic tool regarding MCA mainstem and branch occlusions. Because this method conveys useful information concerning cerebral tissue and clinical prognosis, it may be useful to identify those patients who benefit most from local or intra-arterial thrombolytic therapy.     

Follow-up examinations by transcranial Doppler ultrasound in primary angiitis of the central nervous system

BACKGROUND: Primary angiitis of the central nervous system (PACNS) is a rare disease. The definite diagnosis is made upon proof of mononuclear inflammation of the vessel wall on brain biopsy. The diagnosis can also be established on clinical grounds, typical findings on intra-arterial angiography and other investigatory grounds excluding other diseases. Therapy comprises an aggressive immunosuppressive approach. Close monitoring of the patients is mandatory. Transcranial Doppler ultrasound (TCD) has not yet been used to follow up the vasculitic lesions in PACNS. CASE: We report on a 32-year-old female with massive cerebral infarctions secondary to multiple large-vessel stenoses because of probable PACNS. The patient was followed closely by means of TCD. During therapy the cerebral blood flow velocities normalized as displayed by TCD. Clinical improvement followed several days after normalization of cerebral blood flow. CONCLUSIONS: TCD is a valuable noninvasive bedside tool to monitor cerebral blood flow velocities and therapy response in patients with cerebral vasculitis, if large arteries are involved.     

Positron emission tomography of regional brain metabolic responses to a serotonergic challenge and lethality of suicide attempts in major depression

BACKGROUND: Lower serotonergic activity correlates with high-lethality suicide attempts in major depression. Postmortem studies of serotonin receptors in suicides localize changes to the ventral prefrontal cortex (PFC). We studied serotonergic response in ventral PFC in depressed patients surviving a high-lethality suicide attempt. METHODS: Depressed patients with a history of a high-lethality suicide attempt (n = 16) were compared with those with low-lethality attempts (n = 9) for level of depression, suicidal intent and ideation, impulsivity, aggression, and neuropsychological test performance. Subjects were scanned while medication free after a single-blind placebo and after fenfluramine hydrochloride administration on a second day. Brain responses were measured by positron emission tomography imaging of fludeoxyglucose F 18 and serial prolactin levels. Scans were compared by means of statistical parametric mapping. Correlations of changes in relative regional cerebral uptake (rCMRglu) with clinical and neuropsychological measures were assessed. RESULTS: Depressed high-lethality suicide attempters had lower rCMRglu in ventral, medial, and lateral PFC compared with low-lethality attempters. This difference was more pronounced after fenfluramine administration. Lower ventromedial PFC activity was associated with lower lifetime impulsivity, higher suicidal intent (planning), and higher-lethality suicide attempts. Higher verbal fluency was positively correlated with rCMRglu in the same regions. CONCLUSIONS: Prefrontal localized hypofunction and impaired serotonergic responsivity are proportional to the lethality of the suicide attempt and may mediate the effects of suicide intent and impulsivity on lethality. Positron emission tomographic neuroreceptor studies are needed to determine whether postmortem serotonin receptor findings are also present in vivo and contribute to the abnormal rCMRglu responses.     

Effect of ECT on Cerebral Blood Flow in Melancholia Assessed with SPECT

Ten endogenously depressed patients were studied before, during, and after electroconvulsive therapy. The nature and severity of depression was measured using the Newcastle Rating and Hamilton Depression Scales. The mean number of treatments administered was 12, and all patients recovered. Regional cerebral blood flow was studied using single photon emission computerized tomography (SPECT) with inhalation of (133)Xe. The mean values dropped by 8% after session three and a further 13% after the last session. The flow values of untreated patients was significantly higher than those found in 10 healthy volunteers. The values in patients following the last treatment session did not differ from those in the control group. There were no changes in the regional distribution of blood flow between controls and among patients in the three situations studied. No correlation was found between the physiological data and single items from the rating scales used. Increased cerebral blood flow values found in the treatment situation are due to the presence of depressive illness as such and not to agitation or anxiety. The parallel between flow data and clinical data points to the normalization taking place after, and not during, electroconvulsive therapy.     

Normalization of physical activity on acute ischemic stroke]

The purpose of present study is to clarify the association between early normalization, orthostatic hypotension (OH) and neurological deterioration in patients with acute ischemic stroke. The authors retrospectively performed scheduled ambulation in 162 consecutive patients who were diagnosed as having ischemic stroke without them being comatose. Blood pressure and neurological findings were examined during the orthostatic tolerance test. OH was occurred in 86 (53.1%) of all patients. Neurological worsening were found in 22 of them during all clinical course, although worsening closely associated with orthostatic tolerance was only two of them. Significant OH was occurred in the patients with cerebral arterial stenosis on head-tilt 60 degrees after 15 minutes (p = 0.001). And the patients who have atrial fibrillation also yield OH on sitting immediately after (p = 0.041) and 5 minutes after moving (p = 0.035). Because symptomatic OH were rarely observed in the patients with acute ischemic stroke without them being comatose, early ambulation could be achieved safely.     

The effect of cranioplasty on cerebral hemodynamics: evaluation with transcranial Doppler sonography

BACKGROUND: The purpose of cranioplasty is not only cosmetic repair but also neurological improvement. The effect of cranioplasty on the cerebral hemodynamics flow has not been investigated by ultrasonographic techniques. AIMS: To investigate changes of cerebral hemodynamics after cranioplasty in patients with cranial defect using transcranial Doppler sonography (TCDS). SETTING: The Departments of Neurosurgery and Radiology of a university hospital. DESIGN: A prospective clinical study. MATERIAL AND METHODS: We prospectively examined the cerebral hemodynamics with TCDS pre- and postoperatively in 18 patients with cranial defect who underwent cranioplasty. All postoperative studies were done between the 7th and 15th day after cranioplasty. The anterior cerebral artery was examined through the transtemporal and transorbital windows, the middle cerebral artery through the transtemporal window, and the posterior cerebral artery through the transforaminal window. Bilaterally, the peak systolic, end diastolic and mean blood flow velocities of these arteries were measured. STATISTICAL ANALYSIS: Wilcoxon matched-pairs signed-ranks test. RESULTS: Before cranioplasty all the velocities ipsilateral to the cranial defect were significantly low, while in the contralateral side they were near normal. Ipsilateral low cerebral blood flows increased and reached normal levels (P<0.05) after cranioplasty. During the follow-up, neurological improvement was observed. CONCLUSION: Cranioplasty is carried out not only for preserving normal appearances and physical barrier but also for neurological improvement. This should be explained by the normalization of cerebral hemodynamics.     

The effect of repeated thyrotropin-releasing hormone administration on regional cerebral blood flow in humans

Recently, regional cerebral blood flow (rCBF) was found to increase slightly in the thalamus after a single administration of thyrotropin-releasing hormone (TRH) to healthy adults. Regarding the effect of prolonged TRH administration on rCBF, some scintigraphic improvements have been observed recently. However, no study has investigated the effect quantitatively, except for a preliminary study by positron emission tomography. Therefore, we examined the effect of repeated administration of TRH on rCBF in humans quantitatively. Eight patients with spinocerebellar degeneration (SCD) were given TRH intravenously at a daily dose of 2 mg for 14 days and rCBF was measured by the ¹³³Xe intravenous injection method before and after repeated TRH administration. TRH caused a significant (p < 0.01) increase of 12% in the gray matter flow (fast flow, F|), especially at the parietal and occipital lobes, and also caused a significant (p < 0.05) increase of 8% in the initial slope index (ISI), especially at the parietal lobe. Among seven patients who improved clinically after TRH administration, F₁ values were increased in all of them and ISI values were increased in six. We conclude that repeated TRH administration increases rCBF in humans. These results might warrant clinical investigation of a possible therapeutic role of TRH in patients with cerebral ischemia.     

The pattern of regional cerebral blood flow during alcohol withdrawal - a single photon emission tomography study with 99mTc-HMPAO

Cerebral blood flow was investigated during alcohol withdrawal in 15 male alcoholics by single photon emission computerized tomography with ^99mTc-HMPAO and compared with the results of a second study 3 weeks later when all symptoms of withdrawal had disappeared and when the patients had been free of medication for at least 1 week. Slice images were reconstructed parallel to the orbitomeatal plane, and tracer activity was analyzed in 8 regions of interest per hemisphere. During alcohol withdrawal a special pattern of cerebral blood flow distribution could be observed. Relative perfusion was elevated in both inferior temporal regions, whereas it was reduced in the superior temporal region of both hemispheres. The changes of cerebral blood flow distribution did not correlate with neuropsychological findings nor with the severity of withdrawal syndrome.     

Positron emission tomography and plasma biochemistry findings in schizophrenic patients before and after electroconvulsive therapy

Abstract The clinical effects of electroconvulsive therapy (ECT) on the morbidity of paranoid schizophrenic patients were assessed by positron emission tomography (PET) and plasma biochemistry studies before and after ECT. The present study included five patients whose average age was 41.4 years. The average duration of illness was 23.0 years. To avoid any effect of changes in drugs on PET, no changes were made in the medication of any of the five patients during the study period. ECT improved the clinical symptoms in every patient. Regional cerebral blood flow (rCBF) on PET in both temporal lobes and the left cerebellum was higher in paranoid schizophrenia before ECT than in normal subjects, and rCBF after ECT in both frontal lobes, the right temporal lobe and the right putamen was lower than before ECT as mental symptoms improved. These findings suggest high cerebral blood flow volume in paranoid schizophrenia. Plasma biochemistry studies revealed a lower level of 3-methoxy-4-hydroxyphenylglycol (MHPG) after ECT than before ECT, but a higher level of prolactin existed.     

Correlation between the clinical picture,the EEG and cerebral blood flow after partial occlusion of the middle cerebral artery in man

Summary Quantitative measurements of global and regional cerebral blood flow were performed in 18 patients 1 to 3 days after the onset of symptoms of acute cerebral ischemia due to partial occlusion of the middle cerebral artery and were repeated 21 days thereafter. The first rCBF measurement revealed either an extensive ischemic focus or an ischemic focus with simultaneous reduction of the global blood flow within the corresponding hemisphere in all patients. The later measurements indicated no change in blood flow in the ischemic focus in any case, but there was a slight increase of global cerebral blood flow in 1/3 of the cases.The measurements of cerebral blood flow were correlated with the neurological, psychopathological and EEG findings and in spite of an unaltered cerebral blood circulation, all patients showed a distinct clinical improvement. Various hypotheses for the return of neurological functions in patients with persistent cerebral ischemia are discussed.Paper read at the Kongress der Deutschen Gesellschaft für Neurologie, Hamburg 1975     

Dexamethasone suppression tests in antidepressant treatment of melancholia. The process of normalization and test-retest reproducibility

Pilot studies suggest that changes in response to the dexamethasone suppression test (DST) in melancholic patients receiving antidepressants might represent a laboratory marker of clinical progress. We performed weekly DSTs in 31 hospitalized patients with major depressive disorder, primary and endogenous subtypes, during drug-free and subsequent treatment periods. Most nonsuppressors had progressive normalization of DST responses in conjunction with clinical improvement, DST normalization usually preceded or coincided with good clinical response, and failure to normalize was often associated with poorer clinical outcome. Occasional patients with baseline dexamethasone suppression become nonsuppressive after withdrawal from medication, but the DST has no apparent value as a serial marker in patients with well-documented normal DST findings. Our results extend the construct validity of the DST as a state-related marker in nonsuppressors and suggest future clinical applications.     

Intraoperative monitoring of cerebral blood flow during ventricular shunting in hydrocephalic pediatric patients

Several studies have demonstrated lowered cerebral blood flow (CBF) in patients with hydrocephalus and symptoms of raised intracranial pressure. Ventricular shunting in such cases permits a sudden increase in CBF. The pathophysiology of functional brain deficit secondary to hydrocephalus is little understood. Improvement of the patient's clinical status after drainage of CSF suggests that cerebral dysfunction is not necessarily due to permanent brain damage. In fact, it improves rapidly after ventricular taps. In view of this it would be helpful to monitor cerebral perfusion. The transcranial Doppler (TCD) ultrasonography technique allows real-time monitoring of the intracranial circulation and makes it possible to evaluate the physiopathological correlation between ventricular dilatation and CBF. Continuous monitoring of the middle cerebral artery (MCA) by TCD was performed in three hydrocephalic children (2 months, 14 months, and 8 years old) during a ventricular-peritoneal shunt operative procedure. A TC-2000S device provided by an IMP-F fixed probe was utilized. In all patients, when the lateral ventricle was shunted and the CSF could flow away, a clear and sudden increase of flow velocity above 30% was detected. The pulsatility index (PI) was also pathologically increased in all patients. A gradual normalization of this index was revealed after the shunting procedure. Our experience has to be considered preliminary, but nonetheless, it suggests a clear correlation between hydrocephalic disease and concomitant CBF alterations. A more consistent number of monitoring performances by TCD during operative procedures will improve our understanding of the role of CBF in the development of functional deficits in hydrocephalic disease.Presented at the Consensus Conference: Hydrocephalus '92, Assisi, Italy, 26–30 April 1992     

Is cerebral autoregulation impaired in Parkinson's disease? A transcranial Doppler study

Orthostatic hypotension (OH) is one of the many autonomic disturbances observed in Parkinson's disease (PD). It has been debated whether an additional impairment of cerebral autoregulation (CA) in PD patients may exacerbate the consequences of OH upon brain perfusion. We assessed CA in PD patients and the potential influence of dopaminergic agents. CA was determined by means of transcranial Doppler (TCD) monitoring of the middle cerebral artery (MCA) at rest and during a thigh cuff release test inducing a systemic blood pressure (BP) drop. Fourteen patients were investigated when taking their usual dopaminergic medication and after drug discontinuation for 12 h. A control group was composed of 11 age-matched subjects (CS). In comparison with PD patients, CS presented a significantly higher increase of the mean cerebral blood flow velocities in the MCA after the BP drop. Mean velocities were increased above the initial values in all CS, whereas a flattened curve was observed in PD patients. No significant differences could be further observed between the PD patients regarding the BP, the cerebrovascular resistance, the heart rate and the pulsatility index. These results provide evidence of an impaired cerebral autoregulation in PD patients which appears independent of dopaminergic treatment.     

Pathological cerebral blood flow during motor function in schizophrenic and endogenous depressed patients

In this investigation we examined eight Type I (positive symptoms without marked negative symptomatology), eight Type II (marked negative symptoms) schizophrenic patients of the disordered and paranoid diagnostic subgroups (DSM-III 295.1 and 295.3), eight severely (HAMD above 35) and eight less severely (HAMD below 20) endogenous depressed patients, and eight control persons using the 133Xe inhalation method in resting condition and during motor activity of the dominant right hand. In all patient groups we found flow activation patterns that were different from those observed in normal control persons. During motor activation in Type I schizophrenics and in less severely endogenous depressed patients, we found a bilateral hyperflow and a diffuse cortical flow increase, also involving deeper cerebral structures. In Type II schizophrenics and severely endogenous depressed patients, however, we found a widespread nonreactivity of the regional cerebral blood flow (rCBF) to motor activation, with no flow increase in the contralateral primary motor area. In normal control individuals, we reproduced a 25% flow increase that was strictly limited to the contralateral primary motor area, as already reported by other authors. As only the schizophrenic patients were not under antipsychotic medication (4 with a washout of at least 1 week prior to the investigation, 12 never treated with drugs before), contaminating effects of the medication cannot be ruled out for the endogenous depressed patient groups. However, in schizophrenic patients, these results suggest a diffuse disorganization and lack of laterality of motor functional systems. In addition, the change from hyperactivity to hyporeactivity might indicate cerebral functional correlates of the change from Type I to Type II symptomatology in schizophrenic patients, which could possible prove to be of clinical importance.     

Hemodilution increases cerebral blood flow in acute ischemic stroke

We measured cerebral blood flow in 10 consecutive, but selected, patients with acute ischemic stroke (less than 48 hours after onset) before and after hemodilution. Cerebral blood flow was measured by xenon-133 inhalation and emission tomography, and only patients with focal hypoperfusion in clinically relevant areas were included. Hemodilution was done according to the hematocrit level: for a hematocrit greater than or equal to 42%, 500 ml whole blood was drawn and replaced by the same volume of dextran 40; for a hematocrit between 37% and 42%, only 250 ml whole blood was drawn and replaced by 500 cc of dextran 40. Mean hematocrit was reduced by 16%, from 46 +/- 5% (SD) to 39 +/- 5% (SD) (p less than 0.001). Cerebral blood flow increased in both hemispheres by an average of 20.9% (p less than 0.001). Regional cerebral blood flow increased in the ischemic areas in all cases, on an average of 21.4 +/- 12.0% (SD) (p less than 0.001). In three patients, a significant redistribution of flow in favor of the hypoperfused areas was observed, and in six patients, the fractional cerebral blood flow increase in the hypoperfused areas was of the same magnitude as in the remainder of the brain. In the last patient, cerebral blood flow increased relatively less in the ischemic areas. Our findings show that cerebral blood flow increases in the ischemic areas after hemodilution therapy in stroke patients. The marked regional cerebral blood flow increase seen in some patients could imply an improved oxygen delivery to the ischemic tissue.     

Speculation on the meaning of cerebral metabolic hypofrontality in schizophrenia

Cerebral metabolic hypofrontality in schizophrenia is a controversial research finding. In this article we discuss some of the issues that fuel this controversy, and we speculate on the neural mechanisms that may be responsible for the finding. Most regional cerebral blood flow (rCBF) studies using radioactive xenon have found hypofrontality; the results of positron emission tomography (PET) studies have been less consistent. Several technical factors are discussed that might contribute to the inconsistencies, including airway artifacts with xenon, limitations of tomography in studying the cortex, and approaches to data analysis. The possibility that hypofrontality is a result of medication is also critically examined. The medication factor is still unclear, but most studies of patients before and after neuroleptic medication find that cerebral metabolism goes up, not down, after treatment. The role of patient behavior and experience during an rCBF or PET procedure is an important variable that has not been adequately controlled in most studies. We suggest that this has been the most important variable in interpreting cerebral metabolic data in schizophrenia. Studies of patients examined during a behavior that normally activates prefrontal cortex have consistently found hypofrontality. One theoretical mechanism that could account for hypofrontality as well as many clinical and research findings in schizophrenia is dysfunction of dopaminergic neural transmission at the level of the prefrontal cortex.     

Radionuclide cerebral perfusion scintigraphy in determination of brain death in children

We evaluated a radionuclide scintigraphic technique for imaging relative cerebral perfusion in 18 children who had no evidence of cortical and brainstem function. Patients without scintigraphic evidence of cerebral perfusion all later met criteria for diagnosis of brain death. Patients who failed to satisfy brain-death criteria had persistent scintigraphic evidence of cerebral perfusion. Seven patients with normal scintigraphic studies were being treated with barbiturates and hypothermia at levels that attenuated or completely suppressed EEG activity. Four patients without scintigraphic evidence of cerebral perfusion had mean arterial pressures (MAP) higher than (54.8 +/- 7.6 torr) intracranial pressures (ICP) at the time of scintigraphic study, suggesting that ICP in excess of MAP is not the sole explanation for the absence of cerebral perfusion. Radionuclide cerebral perfusion scintigraphy (RCPS) is a rapid, portable, accurate test that appears to be useful in the diagnosis of brain death in the pediatric population.