Long-term intracranial pressure monitoring.

Continuous or intermittent measurement of intracranial pressure (ICP) is important in patients at risk for raised ICP. Indications exist for short- and long-term measurements. The various methods used for short-term monitoring are discussed with their relative advantages and disadvantages. For long-term measurements of ICP use of a completely implantable telemetric epidural pressure transducer is indicated. No such device is commercially available. We have developed an inexpensive passive telemetric transducer for this purpose. Results obtained up till now have demonstrated its reliability for measurements of two to three months duration. The life span of the device is limited by degrading of the epoxy utilized for sealing of the titanium pressure sensing part to the radiolucent ceramic cap of the transducer, causing leakage of water into the transducer and false low measurements. Because of these problems new hermetic sealing techniques were tested. Both active metal brazing and glass bonding yielded good results and hermetic sealing could be obtained. The metal to ceramic bonding presented is generally applicable within the design of implants. Besides the technical progress reported, the experience with clinical use in 12 patients is presented.

The Rotterdam teletransducer. A telemetric device for measuring epidural pressure.

A discussion on the clinical value of telemetric measurements of intracranial pressure is presented. The technical improvements of an earlier described implantable epidural transducer are reported. Furthermore, the results are given of an in vivo study in dogs of the relation between epidural pressure as measured by this device and ventricular fluid pressure for variable physiologic conditions. An evaluation of the implantation technique is included and a justification for the selection of the constituting materials is given. Clinical results obtained in a patient are illustrated.

Failure of clinical remission after transsphenoidal removal of a microadenoma in a patient with Cushing's disease: multiple hyperplastic and adenomatous cell nets in surrounding pituitary tissue.

A patient with Cushing's disease is described who underwent transsphenoidal adenomectomy of a basophilic microadenoma with a diameter of 3 mm. In a piece of surrounding normal pituitary tissue removed at operation, multiple small nests of adenomatous basophilic cells were found both in the adeno- and neurohypophysis. No clinical improvement was observed. Cortisol secretory rate, plasma ACTH, the absent response of plasma cortisol to insulin-induced hypoglycemia, and the responses of plasma cortisol to lysine vasopressin and TRH remained unchanged. The observations in this patient point to the presence of multiple ACTH-secreting adenomatous cell nests and microadenomas throughout pituitary gland and bring back into view the concept of primary stimulation of hypothalamic corticotropin-releasing factor as the primary derangement in some patients with Cushing's disease.

The incidence of complications during pregnancy after treatment of hyperprolactinemia with bromocriptine in patients with radiologically evident pituitary tumors.

The course of pregnancy achieved after bromocriptine therapy is described in nine patients with radiologically evident prolactin-secreting pituitary tumors. In six patients no complications occurred. No changes in sellar size or secondary endocrine deficiencies developed. In three patients, however, complications developed between the 22nd and 24th weeks of pregnancy. Despite prior external pituitary irradiation, one patient developed transient bitemporal hemianopsia and one patient had apoplexy of the pituitary tumor with transient paresis of the left abducens nerve. A third patient developed parasellar expansion of the pituitary tumor with bone destruction and paresis of the right abducens and oculomotor nerves. After transsphenoidal surgery the paresis of both nerves disappeared. Microscopically, the tissue removed at surgery was a chromophobe adenoma with focal fibrosis and calcifications without recent hemorrhages. In the course of more than 100 pregnancies achieved in The Netherlands after bromocriptine therapy, five patients reportedly developed complications of the pituitary tumor. At present, patients in whom complications can be expected cannot be predicted by the size or configuration of the sella turicica or the magnitude of elevation of the plasma prolactin level. In two patients external pituitary irradiation did not prevent complications during pregnancy.

Epidural pressure monitoring with the so-called Rotterdam transducer. Further in vivo results.

Results of measurements in vivo of intracranial pressure obtained with a new telemetric epidural pressure transducer are described. The relations of epidural pressure to ventricular fluid pressure are studied in acute experiments and found to be linear, but variable. The functioning of 18 transducers was studied over many months of implantation.

Effect of moderate arterial hypotension combined with repeated withdrawal of cerebrospinal fluid on the development of increased ventricular fluid pressure after cold injuries in cats.

The influence of Trimetaphan induced hypotension was studied on the development of increased ventricular fluid pressure after induction of cold injuries of the brain in cats. Hypotension was induced in two series of animals: in one immediately after freezing and in another series after a delay of three quarters of an hour. In the animals not treated with hypotension ventricular fluid pressure increased considerably according to three types of response. In both series treated with hypotension the ventricular fluid pressure and elastance were significantly lower than in the animals not treated; also brain stem herniation tended to occur less frequently in the animals treated. No deleterious effect of the hypotension was seen on cerebral metabolism as measured by the lactate content in the cerebrospinal fluid.