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UNCOMMON THIRD VENTRICLE HERNIATION WITH CYST FORMATION AS A POSSIBLE RESULT OF OBSTRUCTIVE HYDROCEPHALUS

L. M. Vencken” and A. C. J. Slooff**

SUMMARY

An adult man with an unusual cyst formation, originating from the suprapineal recess is described. The cyst may partly be caused by and may partly have contributed to aqueduct- stenosis.

In 1943 PENNYBACKER and RUSSELL reported subtentorial cyst formation after ventricular rupture in hydrocephalus, which resulted from aqueduct obstruction in two patients, in one by proliferation of subependymal glia and in the other by an astrocytoma of the brainstem.

The dilatation of the ventricles was followed by rupture of a Iateral ventricle wall medially in a weak spot which lies between the crus of the fornix and the forceps major. A cyst-like cavity was formed towards the incisura tentorii, the arachnoid being pushed forward. Thus the cyst stayed in the subarachnoid space, insinuating itserf between the tento~um above and the cerebellum and brainstem below.

PERRYMAN and PENDERGRASS (1948) described the possibilny of rupture of the ventricle wall in four different spots: the lamina terminalis, the postero-med,ial wall of the lateral ventricle and the upper part of the roof of the fourth ventricle. Hernistion of the third ventricle into the posterior fossa was found in five patients, A square sign was noticed on the ventriculogram, the extension of the third ventricle being depicted in this form on the anterior posterior X-ray.

We have recently seen ,a similar case.

CASE HISTORY

A 27-year old man had attacks of headache usually during the morning. They had started five years previously and lasted for about half a day, becoming more frequent during the last few months. His headache faded away after vomiting

* Department of Radiology. (Dr. J. Lamers, Dr. G. Vlassenroot, Dr. G. Goedhard, Dr. J. Nievelstein). ** Department of Neurosurgery. (L. N. M. Coene and Dr. A. C. J. Slooff). De Weverziekenhuis, Heerlen, the Netherlands.

Clin. Neurol. Neurosurg. 1975-4

without nausea. No signs of elevated intracranial pressure or meningeal irritation

were found. A detailed ophthalmoIogi~a1 examination reveaied a slight paresis of the superior

oblique muscle of the right eye and minimal myopia of the left eye. Apart from a tremor of both hands that appeared to be familial, no further

neurological signs were elicited. Examination of blood and urine was normal. The skull X-ray showed the clivus to assume a more horizontal position, making

too acute an angle with the axis. However, there was no atlas assimilation or other bony malformation. Movements in the crania-vertebral region proved to be normal. The dot-sum sellae and the posterior clinoid processes were eroded from above and convolutional markings were prominent.

The E.E.G. was grossly abnormal, especially the systems projecting towards the occipital region, but there were no focal signs. The brain scan was normal.

Carotid angiography revealed dilated lateral ventricles. Ventriculography was first performed with metrizamide and several days later repeated with air.

Both times the intracranial pressure appeared to be raised. The cerebrospinal fluid was normal. Both lateral ventricles and the third ventricle were enlarged. The aqueduct was

wide as well, and stenosed midway between the third and fourth ventricles (fig. 1 and 2). Some air entered the cisterna magna but none was seen over the brain

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Fig. 1 and 2. A = aqueduct; 111 = third ventricle; b.h. = burr hole; S.S. square sign; ind. tent. = probable indenta- tion of the cyst by the tento- rium.

surface. Most conspicuous was the large suprapineal recess, which extended under

the tentorium into the posterior fossa as a cystlike formation,

At operation, the occipiital bone was found to be rather thin. Both cerebellar

tonsils were herniated. The fourth ventricle appeared to be normal in size.

It was impossible to probe the aqueduct until the cyst was opened, which was

easily done as it lay partly over the roof of the fourth ventricle. Clear fluid was

drained from the cyst and then a probe could be passed through the aqueduct.

The vermis was split further, so as to obtain a wide passage between the cyst

and the cisterna magna. Control ventriculography showed that the ventricles were

still dilated.

Almost two years after the operation the patient still did well. He resumed his

former education.

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DISCUSSION

In 1967 SCHECHTER and ZINGESSER described variations in radiological features in aqueductal stenosis.

A combination of the latter with a weakened area of the wall of the third ventricle, in or near the suprapineal recess, could be followed by cyst formation.

These supramesencephalic cysts may reach huge proportions. A problem may arise in the differentiation from the Dandy-Walker syndrome.

The authors stressed the necessity to take serial films over a period of hours after the administration of positive contrast in order to indicate the exact po’nt of occlusion of the aqueduct.

We feel that in the case reported the cystic formation might have contributed to a further narrowing and eventual closure, at least temporary, of the aqueduct. however, we could not f’nd a support for this view in the literature.

It seems reasonable to consider the reported herniation of the third ventricle wall as congenital.

We acknowledge the value criticism of Prof. Dr. L. Penning, Groningen, and we are indebted to Dr. C. J. Hagen for his permission to use his record of this patient.

REFERENCES

PENNYBACKER, J., RUSSELL, D. s. (1943) Spontaneous ventricular rupture in hydrocephalus, with subtentorial cyst formation. J. Neurol. Psychiat., 6, 38.

PERRYMAN, c. R., PENDERGRASS, E. P. (1948) Hemiation of the cerebral ventricles. Amer. J. Roentgenol. 59, 27.

SCHECHTER M. H., ZINGESSER, L. H. (1967) The radiology of aqueductal stenosis. Radiology 88, 905.