Ethical aspects of research on brain morphology in psychiatric patients

Morphometric and functional brain research is now an integral part of the most concentrated effort in a century to understand some of the most distressing illnesses to which man can fall victim. It will undoubtedly expand. The only ones with anything to fear from this work are those who, for ideological reasons, cannot accept its basic premises. The ethical issues it raises are not in general insurmountable, though the questions posed by the concept of informed consent remain.

The morbidity of CT air meatography: a follow-up of 84 patients

At present CT air meatography is the examination of choice for all patients suspected of having a small acoustic neuroma not demonstrated by high resolution contrast enhanced computed tomography. Several publications have indicated that the examination is innocuous and can be carried out on an outpatient basis. An analysis of the side effects of this procedure in 84 patients suggests that it carries a significant morbidity and patients undergoing this examination should be admitted to hospital for at least 24 hours.

Virtues and vagaries of high-resolution CT air cisternography in the diagnosis of acoustic neuromas

A series of 125 consecutive, bilateral, high-resolution, computerized tomographic (CT) air cisternograms was prospectively reviewed and analyzed. Emphasis was placed on identifying problems encountered in performing the study and potential sources of error in interpretation. In two patients there was difficulty in transporting the air bolus because spinal cord tumors coexisted with bilateral acoustic neuromas. Potential false-positive results were avoided in four patients by persistent efforts to fill the internal auditory canal. Later reexaminations were recommended for four patients whose examinations were suspicious or suggestive of tiny acoustic neuromas. Unilateral Mondini malformation was incidentally diagnosed in one patient. Six patients required therapy for persistent headache after lumbar puncture. High-resolution CT air cisternography is believed to be the method of choice for investigating the nonenhancing or small acoustic neuroma. However, this method is not without potential problems, some of which are discussed.

Childhood choroid plexus neoplasms. A study of 14 cases less than 2 years old

Fourteen children less than 2 years old with choroid plexus papilloma (CPP) were studied. Of these patients nine had the tumor in the lateral ventricles (LV), three in the fourth ventricle (4th V), one in the third ventricle (3rd V) and one in the third and left lateral ventricle (LLV). Ten cases showed benign CPP, three cases malignant CPP, and one case had a venous malformation of the choroid plexus (VMCP). Computed tomography (CT) was the best method for neuroradiological study, although a very small CPP in the 3rd V was not detected in an early study. Malignant and benign CPP can be differentiated with CT, especially if the study is performed with contrast media. Pneumoencephalography must be rejected because it is very dangerous and may be the cause of death in some cases. The follow-up of patients with CPP showed a poor prognosis, even after correctly removing the tumor and inserting a shunt.

Focused encephalography

Focused encephalography is a diagnostic procedure performed after computed tomography (CT) that can be specifically focused on diagnostic problems not solved by CT. The authors have used the procedure in 20 cases, and it has proved to be quick, risk-free, and without serious side effects. It provides useful supplementary diagnostic information, and can be especially helpful when CT is not available or when the CT scanner is an early-generation model.

Neuroradiological detection of small and intracanalicular acoustic tumors: an emphasis on CO2 contrast-enhanced computed tomographic cisternography

Seventy patients suspected clinically of having an acoustic tumor were evaluated using the computed tomographic (CT) scan as the initial neuroradiological procedure, followed by CO2 contrast CT cisternography in cases where the intravenous contrast-enhanced scan did not reveal any lesion. Forty-eight gas CT cisternograms revealed 10 small acoustic tumors, 2 of which were totally intracanalicular. The authors present a review of the basic CT anatomy of the temporal bone as it relates to acoustic tumors. Based upon the ease of performance of the procedure, the low postexamination morbidity, and the excellent diagnostic results, CO2 CT cisternography is recommended as the procedure of choice in the diagnosis of small and intracanalicular acoustic tumors.

DDAVP, a synthetic analogue of vasopressin, in prevention of headache after lumbar puncture and lumbar pneumoencephalography

In a double-blind controlled trial the possible prophylactic effect of intranasally applicated DDAVP (1-desamino-8-arginine vasopressin, Minurin)--a synthetic analogue of vasopressin--is evaluated regarding the incidence of headache following lumbar puncture (LBP) in 51 patients and following pneumoencephalography (PEG) in 28 patients. DDAVP had no statistically significant effect on the incidence of headache or on the consumption of analgesics in the DDAVP-versus placebo groups (minimal relevant difference = 50%, 2 alpha = 0.05, beta = 0.50).

Cardiac arrhythmia induced by pneumoencephalography

Cardiovascular collapse associated with pneumoencephalography (PNE) has been reported but there has been no prospective study of its nature and cause. We have recorded prospectively the e.c.g. of 82 unselected patients, with no cardiovascular or metabolic disease, undergoing PNE under general anaesthesia. The frequency of arrhythmia following air injection was 60%; bradycardia 22%; ventricular ectopic beats 26%; nodal rhythm or sinus tachycardia 11%. Cardiovascular collapse occurred in three patients; two with "torsades de pointes" and one with bigeminy and q.r.s. block. Arrhythmia was more frequent in patients with a pituitary tumour and intracranial hypertension (91%). Eight postoperative control PNE examinations were uneventful. Three of four patients with frontal lobe tumours and four of seven with posterior fossa tumours exhibited arrhythmia.

[Long-term follow-up study of the absorption of gas after encephalography in dilated intracranial cerebrospinal fluid spaces (author's transl)]

The absorption of gas after encephalography in different groups of patients was investigated in a long-term follow-up study. Group I (11 patients) showed no pathological findings in the encephalogram. Group II (8 patients) had encephalographic signs of diffuse cerebral atrophy. Group III (7 patients) demonstrated in the encephalogram characteristics of normal pressure hydrocephalus with variously located blocks of air in the subarachnoid space. In group I the gas located in the subarachnoid space had usually disappeared after 24 h, in some cases after 72 h. In group II the pattern of resorption was basically similar, although in one case cortical air could be seen at 96 h. In group III the absorption of air from the subarachnoid space began after 72 h in radiological relevant amounts. In none of the cases of group III could similar short times of resorption be seen in comparison to group I. It is considered that these two groups can be clearly distinguished from each other in the duration of resorption of air from the subarachnoid space. The importance of encephalography as a pathophysiological tool for investigation of both the disturbed resorption and circulation of the cerebrospinal fluid in normal pressure hydrocephalus is stressed.

[Effect of tiapride on the side effects of cerebrospinal fluid depletions in spinal puncture, pneumoencephalography and air myelography]

The authors report their experience of the treatment post-cerebrospinal fluid loss syndrom, following subtraction by lumbar puncture, pneumoencephalography and air myelography. The study of 70 patients, divided in two equal groups, one receiving classic therapy, one receiving tiapride, a new molecule of original conception, lead to emphasize the interest of this drug. Tolerance in general is good, despite the administration of high doses and effects on the syndrom are positive and remarkable in preventive and curative treatment.

Retinal haemorrhage as a complication of gas encephalography and gas myelography. Prospective study using oxgen gas with a discussion of pathogenetic mechanisms

Seventy patients, submitted to oxygen encephalography and oxygen myelography, were examined by retinal funduscopy to establish the incidence of intraocular haemorrhages, a complication reported to be frequent by other investigators. We did not discover any retinal haemorrhages. Pathogenetic factors influencing intracranial or intraocular venous pressure or both are discussed, particularly the effect due to different technical procedures during the examination, and the type of anaesthesia used.

Effects of general anaesthesia on size of cerebrospinal fluid spaces during and after pneumoencephalography

The mode of anaesthesia used during pneumoencephalography has a significant effect on the size of the cerebral ventricles 24 hours after the procedure. Post-encephalographic ventricular enlargement is less marked in patients examined under nitrous oxide anaesthesia. This appears to be related to passage of the gas into the ventricles during the encephalogram, and subsequent diffusion outwards. Variations in arterial carbon dioxide tension during the anaesthesia do not contribute significantly to changes in ventricular size. However, both hyperventilation and inhalation of nitrous oxide may cause apparent increase in size of the cerebral sulci.

Complications of cerebral angiography and pneumography

There were incidences of 0.7% severe and 5.5% mild complications in 1,971 direct puncture carotid angiograms done over a 5-year period. In 1,035 retrograde branchial angiograms, there was a 0.6% incidence of severe, and a 4.7% incidence of mild, complications. Complications tended to increase with increasing age of the patient. Brachial angiography is virtually free of life-threatening complications, and the incidence of neurological sequelae was markedly less than that shown by a comparable analysis of catheter angiography. Of patients undergoing 1,542 fractional pneumoencephalograms, 2 had severe complications.

[Determination of 11-hydroxycorticosteroids in stress-evoking interventions as an endocrinological test]

Determinations of the 11-hydroxycorticosteroids (11-OHCS) in intervention evoking stress proved as advantageous method for the estimation of the ACTH-reserve. After pneumencephalography or transethmoidal-transsphenoidal operations of the hypophysis intensive increase of 11-OHCS in the plasma and urine were observed, when the ACTH-reserve was intact. The investigations give the possibility of renouncing additional special functional tests.

[Pituitary apoplexy after pneumoencefalogram]

A case of pituitary apoplexy following the performance of a pneumoencephalogram is reported. No such a case has been published in the literature, to the author's knowledge. The etiopathogenetic mechanism is discussed and a recomendation is made that surgery should be performed straight after completion of the pneumoencephalogram, should it show a significant supraselar extension of a pituitary adenoma, even in the absence of increased intracranial pressure.

Intraocular haemorrhage as a complication of pneumoencephalography

The ocular fundi of 20 patients were examined before and after pneumoencephalography. In four of these, fresh venous retinal haemorrhages were seen, and a further patient had developed an exudate. Possible reasons for a rise in retinal venous pressure include bodily inverting the patient, compression of the thorax, the use of positive pressure respiration, and the air injection itself. It may be advisable to take steps to limit the effects of such possible causative factors.

Subacute combined degeneration of the spinal cord and air encephalography

Subacute combined degeneration of the spinal cord is a rare complication of vitamin B12 deficiency and is seldom encountered today. A case of Addisonian pernicious anaemia is reported in which the classical signs of subacute combined degeneration developed suddenly after air encephalography had been performed. The patient made a complete recovery.

[Changes in cerebrospinal fluid pressure in nitrous oxide anesthesia in neurosurgical patients]

By employing continual electromamometry of the cerebrospinal fluid and central venous pressures the influence of nitrous oxide on the CSE pressure was studied in neurosurgical patients operated upon following pneumoencephalography. In patients treated surgically without any preliminary pneumoencephalographic investigation the normo- and hypocapnic artificial ventilation of the lungs with a N2O and O2 mixture produced a significant drop of the CSF pressure. A nitrous oxide anesthesia applied to the patients operated on after pneumoencephalography was accompanied by a marked rise of the cerebrospinal fluid tension. In such cases an artificial hyperventilation of the lungs failed to prevent a rise of the intracranial tension.

[The use of nitrous oxide as a contrast medium during fractionated gas encephalography in halane-nitrous-oxide anesthesia]

40 children were employed as test cases in fractionated gas encephalography using Halan-nitrous oxide anesthesia, and the level of cerebrospinal pressure, the röntgenoparent quality of the extracerebral spaces and the duration of postencephalographical symptoms were examined using air and nitrous oxide as contrast media. In the course of the examination the cerebrospinal pressure showed a tendency to rise when air was introduced, to fall when nitrous oxide was introduced. After instillation of N2O however the filling of the subarachnoid space was over so quickly that it could not be included in the assessment. Sufficient röntgenograms were obtained for all diagnostic demands through 'hybrid filling', (introduction of nitrous oxide into the ventricles, introduction of air into the subarachnoid spaces). With the aid of the results obtained from this examination attempts will be made to derive differentiated indications for filling with nitrous oxide.

Determination of intracerebral structures using osseous reference points for computer-aided stereotactic operations

Computer-aided sterotactic neurosurgery can be improved and simplified by using craniocerebral parameters for the calculation of subcortical target points and avoiding an air-filling of the ventricles. This was achieved by selecting 403 pneumo-encephalographic studies at random, measuring the craniocerebral parameters according to age and sex. There is a correlation between the bony cranium and the brain axis. We established a formula and a table to determine in the plain X-ray the entrance of the foramen of Monroi with a standard deviation of +/- 1.5 mm and the inclination of the intracerebral basic line we used (foramen Monroi-commissura posterior). With this information various subcortical targets can be determined by means of computer programs.

Acute pulmonary edema following venous air embolism during a neurosurgical procedure. Case report

✓ A case of venous air embolism during a procedure in the sitting position is reported in which the patient developed fulminant pulmonary edema within 2 hours of the embolus. Possible cause and effect relationships are discussed.