Evaluation and measurement of the normal ventricular and subarachnoid spaces by CT

[Intramedullary spinal cord tumors and hydrocephalus: an analysis of the results of surgical treatment in 541 patients]

The article addresses the problem of intramedullary tumors (IMTs) combined with hydrocephalus (HC).

PURPOSE

The study purpose was to explore, based on large clinical material, the occurrence of hydrocephalus combined with intramedullary tumors, possible pathogenetic mechanisms of its development, effect of tumor resection on the course of hydrocephalus, and need and timing of shunting surgery.

MATERIAL AND METHODS

We present and analyze the data of the largest individual series of patients of all age groups operated on for IMTs of the spinal cord: 541 patients; 586 operations; age from 2 months to 72 years.

RESULTS AND CONCLUSION

Our findings confirm a potential pathogenetic relationship between IMT and HC. The overall occurrence rate of HC in IMT patients was 6.3%. In patients with benign tumors (WHO Grade 1-2; 449 patients), HC developed in 25 (5.6%) cases; in patients with malignant tumors (WHO Grade 3-4; 84 patients), HC developed in 7 (8.3%) cases. A statistically significant prevalence of cervico-medullary tumors was found in HC patients: 19 (59.4%) cases. According to our data, dissemination of the tumor process is a potential factor of HC development.

Valutazione quantitativa dell'atrofia cerebrale in tomografia computerizzata

L'impiego in TC di misure oggettive del grado di dilatazione degli spazi subaracnoidei e ventricolari è stato sempre ricercato, ma raramente con successo, per la difficoltà di riprodurre le misure non solo fra diversi autori ma anche nell'esperienza del singolo.

Scopo di questo lavoro è operare una revisione degli articoli pubblicati dal 1982 ad oggi per valutare se sia possibile proporre una metodica di ampia e semplice applicazione.

Se l'indice dei corni frontali è diffusamente impiegato per valutare la dilatazione ventricolare e mostra una buona correlazione con l'atrofia cerebrale, non sembra esistere un indice altrettanto affidabile che possa essere utilizzato per la valutazione della dilatazione degli spazi subaracnoidei.

Abbiamo pensato di proporre un indice di area basato sul rapporto fra superficie degli spazi subaracnoidei e superficie dell'area interna del cranio.

L'indice descritto è attualmente in uso e ci riserviamo di riferire più avanti su una sua eventuale validazione statistica.

Inter-racial, gender and aging influences in the length of anterior commissure-posterior commissure line

OBJECTIVE

The length of anterior-posterior commissure (AC-PC) in racial groups, age, gender of patients with deep brain stimulation (DBS) and pallidotomy were investigated.

METHODS

From January 1996 to December 2003, 211 patients were treated with DBS and pallidotomy. There were 160 (76%) Caucasians, 35 (17%) Hispanics, 12 (5%) Asians and 4 Blacks (2%). There were 88 males and 52 females in DBS-surgery group and 44 males, 27 females in pallidotomy group. Mean age was 58 year-old. There were 19 males and 19 females and mean age was 54.7 years in the control group. Measurements were made on MRI and @Target software.

RESULTS

The average AC-PC distance was 24.89 mm (range 32 to 19), which increased with aging until 75 years old in Caucasian and also increased with aging in Hispanic, but the AC-PC distance peaked at 45 years old in Hispanic. The order of AC-PC distance were 25.2+/-2 mm in Caucasian, 24.6+/-2.24 mm in Asian, 24.53 mm in Black, 23.6+/-1.98 mm in Hispanic. The average AC-PC distance in all groups was 24.22 mm in female who was mean age of 56.35, 25.28 mm in male who was mean age of 60.19 and 24.5+/-2 mm in control group that was excluded because of the difference of thickness of slice. According to multiple regression analysis, the AC-PC distance was significantly correlated with age, race, and gender.

CONCLUSION

The AC-PC distance is significantly correlated with age, gender, and race. The atlas of functional stereotaxis would be depended on the variation of indivisual brain that can influenced by aging, gender, and race.

Ventricular volume change in childhood

OBJECT

The aim of this study was to construct a model of age-related changes in ventricular volume in a group of normal children ages 1 month to 15 years, which could be used for comparative studies of cerebrospinal fluid circulation disorders and cerebral atrophy developmental syndromes.

METHODS

A magnetic resonance imaging-based segmentation technique was used to measure ventricular volumes in normal children; each volume was then plotted against the child's age. In addition, intracranial volumes were measured and the ratio of ventricular to intracranial volume was calculated and plotted against age. The study group included 71 normal children, 39 boys and 32 girls, whose ages ranged from 1 month to 15.3 years (mean 84.9 months, median 79 months). The mean ventricular volume was 21.3 cm3 for the whole group, 22.7 cm3 in boys and 19.6 cm3 in girls (p = 0.062, according to t-tests). The mean ventricular volume at 12 months for the whole group was 17 cm3 (20 cm3 in boys and 15 cm3 in girls), representing 65% of the volume achieved by 15 years of age (87% in boys and 53% in girls). The volume increased by a factor of 1.53, to 26 cm3 (23 cm3 in males and 28 cm3 in females, increase factors of 1.15 and 1.86, respectively) at 15 years of age. The change in ventricular volume with age is not linear, but follows a segmental pattern. These age periods were defined as: 0 to 3, 4 to 6, 7 to 10, and 11 to 16 years. A statistical difference based on sex was only demonstrated in the first 6 years of life. The mean ventricular volume for the first 6-year period was 22.4 cm3 in boys and 15.7 cm3 in girls, and the difference was significant for the two sexes (linear regression analysis for age and sex, significant according to analysis of variance regression at 0.007, p = 0.108 for age, p = 0.012 for sex). Thereafter, there was no significant difference in ventricular volume between boys and girls with further growth. The ratio of ventricular volume to intracranial volume was 0.0175 for the whole group, 0.017 in boys and 0.018 in girls (p = 0.272, according to t-tests). At 12 months of age the ratio was 0.019; it stabilized to 0.015 at 8 years of age, and increased to 0.018 at 15 years of age. No statistical difference based on sex was demonstrated with growth.

CONCLUSIONS

The ventricular volume in normal children increases with age by a factor of 1.5; the increase is in a nonlinear segmental pattern. Boys have significantly higher ventricular volumes only in the first 6 years of life. The ventricular/intracranial volume ratio remains stable throughout childhood.

Cerebellar atrophy does not increase susceptibility to carbamazepine toxicity

Cerebellar atrophy (CA) is a frequent finding in patients with chronic epilepsy. To find out whether the existence of CA has an influence on the tolerance of high-dose monotherapy with carbamazepine, we compared the lowest individual toxic serum levels in patients with complex focal seizures, with CA (n = 27) and without CA (n = 20) in computerized tomography (CT). There was no statistical difference between the groups, even after separating patients with mild CA (n = 20) from those with more severe damage (n = 7). In addition, other clinical, EEG and CT data also seemed to have no influence on the individual toxic threshold serum levels of carbamazepine.

Interobserver variability in CT assessment of brain atrophy

To assess interobserver variability in estimation of brain atrophy based on CT, four neuroradiologists examined CT brain images of 150 consecutive patients without focal lesions. An independent neuroradiologist made the following quantitative measurements: frontal horn index, subarachnoid space area and the ratio between subarachnoid space area and inner skull space area. Level of agreement was fair for the presence (k = 0.24), slight for the degree (mild, moderate, severe) (k = 0.24) and moderate for the type (cortical, subcortical, mixed) of atrophy (k = 0.59). There was a highly significant correlation between the number of observers agreeing and quantitative measurements. We concluded that neuroradiologists' subjective estimation of brain atrophy alone is not reliable. Quantitative measurements would be needed in cases where the presence of brain atrophy might determine clinical decisions.

Craniofacial skeletal measurements based on computed tomography: Part I. Accuracy and reproducibility

Computed tomography (CT) is a useful modality for the management of craniofacial anomalies. A study was undertaken to assess whether CT measurements of the upper craniofacial skeleton accurately represent the bony region imaged. Measurements taken directly from five dry skulls (approximate ages: adults, over 18 years; child, 4 years; infant, 6 months) were compared to those from axial CT scans of these skulls. Excellent agreement was found between the direct (dry skull) and indirect (CT) measurements. The effect of head tilt on the accuracy of these measurements was investigated. The error was within clinically acceptable limits (less than 5 percent) if the angle was no more than +/- 4 degrees from baseline (0 degrees). Objective standardized information gained from CT should complement the subjective clinical data usually collected for the treatment of craniofacial deformities.

Volume determinations of the encephalic ventricles with CT and MRI

The volume of the encephalic ventricles was determined from magnetic resonance imaging (MRI) scans. Since there are many conditions in which the encephalic ventricles become enlarged such as Alzheimer's disease and hydrocephalus, accurate measurement of the ventricles provides a valuable and safe means of aiding the diagnosis of such conditions and also provides important follow-up information in affected patients. The objective was pursued in a three phase study. This paper presents the data obtained from the first phase. This first phase demonstrated the possibility of measuring fluid filled spaces by MRI in three phantom preparations (small, medium, and large "ventricles"). The results were compared with those obtained from computerized tomography (CT) scans of the same preparations. These volumetric calculations were done with the aid of a Calcomp 9,000 digital analyzer programmed to compensate for the scale factor and slice thickness of the images. The phantom study showed that the results obtained from the MRI scans were better than those obtained from the CT scans in measuring the volume of water-filled cavities (ventricles) in gelatin phantoms. The average percent difference between volumes obtained by an imaging procedure compared to the actual volume as determined by water displacement was 15.8% for CT scanning and a more impressive 8.3% for MRI.

Electroconvulsive therapy and cerebral computed tomography. A prospective study

Cerebral computed tomography (CT) was performed before and after right-sided electroconvulsive therapy (ECT) in 40 patients aged 26-87 years with major affective disorders. Nine patients with a concomitant definite or possible non-acute organic brain disorder were included. Several patients had long seizure durations, maximum 6.5 min, caused by hyperventilation-induced hypocapnia. Twenty-nine patients received at least 16 treatments (maximum 46). No CT changes occurred following ECT. A questionable dilatation of the left temporal horn in a 69-year-old hypertensive man who recovered completely without side effects after 3 ECT sessions was probably unrelated to the ECT. Provided sufficient oxygenation, even relatively long ECT series and seizures lasting several minutes do not cause any brain damage visible on CT.

Quantitative evaluation of pontine atrophy using computer tomography

Pontine volume was measured and evaluated by computer tomography (CT) in 37 healthy adults and in 29 adult autopsied brains which did not have chronic neurologic diseases. The pons was cut serially into 5 mm slices in the autopsied brains. In the CT examinations both 5 mm and 2 mm slices were studied. Pontine areas in horizontal planes were measured using an image analyzer, then pontine volume was calculated by accumulation of the mean value of the areas and cranio-caudal length. Pontine volume was approximately 19 cm3 and pontine atrophy could be defined as less than 12 cm3 (i.e. the mean - 2 SD) in both methods, which heretofore have not been reported.

Evaluation of brainstem auditory evoked responses in congenital hydrocephalus

Brainstem auditory evoked responses (BAER) were studied in 20 children with clinically diagnosed and CT-confirmed congenital hydrocephalus before and after shunt surgery. Ninety-five percent of the children showed abnormal responses preoperatively. Prolonged wave V latency was the most common abnormality, followed by increased interwave latencies. Total absence of evoked responses was more common in children with communicating hydrocephalus. Following shunt surgery 50% of cases returned to normal and 20% showed a significant improvement. Abnormalities persisted in 10% of cases. BAER abnormalities referrable to caudal brainstem dysfunction recovered first, following CSF diversion. Study of BAER is useful for identifying physiological brainstem abnormalities in hydrocephalic children and promises to be a sensitive non-invasive diagnostic tool for the detection of "non-infective complications" of shunt surgery, if performed serially during follow up.

Tomografia cerebral computadorizada e esquizofrenia: revisão crítica da literatura

Vários estudos sobre tomografia cerebral computadorizada (CT) relatam alteração da estrutura cerebral em esquizofrenia. A grande variação da prevalência e da localização das anomalias pode estar relacionada à heterogenidade da amostra estudada, à escolha das medidas de CT ou ao uso de diferentes critérios diagnósticos. Apesar de alguns achados contraditórios, parece estabelecido que um subgrupo de pacientes esquizofrênicos apresenta atrofia cerebral discreta ou moderada; esse subgrupo se caracterizaria por apresentar cronicidade da doença, pior resposta ao tratamento neuroléptico e pela presença de outros sinais de disfunção cerebral difusa, como distúrbios neuropsicológicos, anormalidades no EEG e «soft signs» neurológicos. Sinais de atrofia na CT foram observados em pacientes esquizofrênicos jovens, no primeiro surto psicótico, indicando que o desenvolvimento das anomalias estruturais não é conseqüência do tratamento ou da cronicidade da doença. Nos diferentes estudos, pacientes com atrofia apresentaram menor carga genética (história familiar para a esquizofrenia) e se observou com maior freqüência história de complicações na gestação, no parto e trauma craniano nos primeiros anos do desenvolvimento. Em face da possibilidade de que doentes esquizofrênicos com atrofia cerebral formem um subgrupo homogêneo quanto à clínica e à etiopatologia da doença, é importante identificar e estudar as alterações da CT e caracterizar esse subgrupo de pacientes.

Intracranial spaces in childhood macrocephaly: comparison of length measurements and volume calculations

CT scanning was done to calculate the volume of intracranial spaces in children with the purpose of developing a reliable method of differentiating the various causes of macrocephaly. The technique has been applied to the CT scans of 60 apparently normal children, and the resulting graphs show the normal relationship between intracranial volumes and age from birth to 15 years. The measurements for 25 children with macrocephaly and normal rate of growth of head circumference were then compared with the reference values. It was possible to make accurate differentiations between megalencephaly, extraventricular hydrocephalus and communicating hydrocephalus. The advantage of this technique in relation to length measurements on CT scans is discussed. The authors advocate the estimation of the product of head circumference and head height as a much more reliable indication of normal and deviant head-size than head circumference alone.

Minamata disease demonstrated by computed tomography

Computed tomography was studied in the patients with Minamata disease, a methylmercury poisoning caused by the ingestion of contaminated sea foods. The characteristic changes in the acquired cases were atrophy of the visual calcarine cortex and of the cerebellar vermis and/or hemisphere. Marked atrophy of the calcarine cortex produced the sac-shaped low density areas between the occipital lobes and diffuse and marked cerebellar atrophy with enlargement of the fourth ventricle and cisterns of the posterior fossa produced a shrunken image on CT. Morphometric analysis confirmed these findings. In the fetal cases, the changes on CT were slight and no definite atrophy was demonstrated in either the calcarine cortex or the cerebellum. Morphometric analysis disclosed an increase of size of the middle portions of the lateral ventricle and the third and fourth ventricles.

A comprehensive study of chronic schizophrenic patients. II: Biological, neuropsychological, and clinical correlates of CT abnormality

There are numerous reports of lateral cerebral ventricle enlargement on computed tomography (CT) in schizophrenics, but the significance and its relationship to traditional notions of organicity remain unclear. Therefore we studied a subgroup of chronic schizophrenics who had lateral ventriculomegaly (and also cortical hyperdensity) on a battery of relevant biological, neuro-psychological, and clinical parameters such as electroencephalogram (EEG), platelet monoamine oxidase (MAO) and serum dopamine-beta-hydroxylase (DBH) activity, the Halstead Reitan Neuropsychological Battery (HRB), premorbid personality adjustment, drug response, positive and negative symptoms, employment history, and family history. Our findings support the notion that there is an "organic" subgroup of schizophrenia that has 1) CT structural abnormalities such as lateral ventricle enlargement and cortical hyperdensity; and cerebral dysfunction or deficits as evidenced by 2) an increased incidence of abnormal EEGs and also 3) greater impairment on neuropsychological tests. The biochemical measures, platelet MAO and serum DBH activity, nor any of the clinical measures could differentiate between the subgroups. The implications of these findings for the subtyping of schizophrenia are discussed.

Correlation of clinical signs with CT findings in patients with cerebellar disease

The severity of cerebellar signs and the degree of cerebellar atrophy depicted by computed tomography (CT) were independently graded in 108 patients with cerebellar disorders. The overall agreement between these independently scaled measures was only 28%. In patients with involvement of the cerebellar hemispheres and anterior lobe, clinical signs tended to be more pronounced than the cerebellar atrophy revealed by CT. The opposite was true for patients with lesions of the caudal vermis. Patients with Friedreich's ataxia had no or only minor CT abnormalities. Close correlation between the degree of infra- and supratentorial atrophy was found only in chronic alcoholics. The poor correlation between changes in cerebellar structure detected by CT and clinical disability suggests the need for caution in CT interpretation.

Normal pressure hydrocephalus: correlation between CT and measurements of cerebrospinal fluid dynamics

Twenty-nine patients consecutively admitted for consideration of CSF diversion surgery for suspected communicating ("normal pressure") hydrocephalus underwent cranial computerized tomography (CT) and study of cerebrospinal fluid (CSF) absorption, the latter determined as resistance to outflow of CSF (Ro). From the CT the size of the ventricular system was determined by various linear measurements and ratios and the presence of periventricular lucencies (PVL) and the size of cortical sulci was noted. Except for absence of cortical sulci greater than 3 mm no CT feature was suggestive of compromised CSF absorption. On the other hand, cortical atrophy did not rule out increased resistance to CSF-outflow. Features thought of as characteristic for normal pressure hydrocephalus on CT: large ventricles as compared with the amount of cortical atrophy and presence of PVL, correlated poorly with measured high resistance values. There was no correlation between the size of the ventricular system and resistance to CSF outflow. In the diagnostic distinction between communicating ("normal pressure") hydrocephalus and cerebral atrophy (hydrocephalus ex vacuo) static CT cannot replace an actual determination of CSF outflow resistance.

Extradural hematomas: Measurement of size by volume summation on CT scanning

The method of volume summation (V = T(A1 + A2 ... An) was used to measure the size of extradural hematomas. The accuracy was tested on six different artificial silicone hematomas and the mean difference was -2.7 ml, SD 3.7 ml. The reproducibility was tested on CT scans of clinical hematomas, SD was 2.1 ml. An empirical formula for volume estimation then found: 0.5 X height X length X depth was moderately reliable, while midline shift and "vesselfree space" were poor indicators of size. In conclusion, the volume summation with manual outlining was found to be highly accurate, but the problems of CT smoothing, spectral shift artifact, partial volume effect and separation of the hematoma from other structures must be considered.

The ventricular system in chronic schizophrenic patients. A controlled computed tomography study

Twenty-three chronic schizophrenic patients and 23 controls, all males between 20 and 40 years of age, were evaluated by CT scan. The lateral, third and fourth ventricles, the Sylvian fissures, and the largest sulcus from each of the frontal, parietal, and occipital lobes, were measured in order to determine whether the previously reported ventriculomegaly in schizophrenics was perhaps due to a disturbance of CSF flow or to atrophy, two common causes of ventricular enlargement. We found that in the schizophrenic group the third and fourth ventricles and both Sylvian fissures were significantly enlarged, but not the lateral ventricles or cerebral sulci. Our data suggest that these ventricular changes are not due to a disturbance of CSF flow or to cerebral atrophy. Other possible explanations are discussed.

The assessment of changes in brain volume using combined linear measurements. A CT-scan study

All linear measurements employed for evaluation of brain atrophy, were performed on 148 computed tomograms of patients aged 28 to 84 without evidence of any nervous system disorder. These included size of lateral, third and fourth ventricles, width of the Sylvian and frontal interhemispheric fissures and cortical sulci and size of the pre-pontine cistern. Various parameters indicated decrease in brain mass with age. Since the atrophic process is a diffuse phenomenon, integration of several measurements evaluating separate brain regions was made. The bicaudate ratio and the Sylvian fissure ratio (representing both central and cortical atrophy) were combined arithmetically, resulting in a correlation of 0.6390 with age (P less than 0.0005). With a computed canonical correlation analysis; a formula was obtained which combined measurements of the lateral and third ventricles, the Sylvian fissure and the pre-pontine cistern. This formula yielded a correlation of 0.67795 (P less than 0.0005). These linear measurements will allow simple and reliable assessement of reduction in brain volume during the normal aging process and in disorders accompanied by brain atrophy.