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Biomedical subjects

P D Croissant

Publications and source records attributed to P D Croissant.

13 recordsLinked to original sources
PubMed1995

Intraradicular disc herniation: a case report and review of the literature.

Intradural disc herniation accounts for < 0.3% of all disc herniations. Intraradicular disc herniation accounts for 4.1% of all such cases. Preoperative diagnosis is difficult, and a high index of suspicion during surgery is required for the diagnosis. We present a patient with intraradicular disc herniation in the lumbar region whose symptoms were severe enough to recommend surgery. The myelogram showed a block at the involved nerve root. Diagnosis of intraradicular herniation was made during surgery. The symptoms were immediately relieved by surgery. The literature on intradural and intraradicular disc herniation is reviewed.

Humans↗
PubMed1978

Megalencephaly in infants and children. The possible role of increased dural sinus pressure.

Seven children studied because of clinical macrocephaly and suspected hydrocephalus ultimately proved to have megalencephaly apparently due to an increase in sagittal sinus venous pressure as established from infusion studies. Unexplainably, these patients were all males. All were seen initially between 2 and 8 months of age. Head enlargement exceeded two standard deviations in all seven. Pneumoencephalography, ventriculography, or computerized tomography demonstrated normal or minimally enlarged ventricles that did not progress in size. Isotope cisternography was abnormal. Studies of CSF formation and absorption demonstrated normal absorption rates but high calculated sagittal sinus pressures. Though therapy was usually not required, in one unusual infant, severe progressive macrocephaly with minimal hydrocephalus required a shunt. Another had a transient episode of acute hydrocephalus associated with a low CSF absorption rate and ventricular enlargement. In this report, we review the intracranial hydrodynamics of benign intracranial hypertension (BIH), communicating hydrocephalus, and the pathogenesis of megalencephaly. Benign intracranial hypertension and the type of megalencephaly demonstrated by our patients appear to develop similarly except that the presence of open cranial sutures may allow a transient nonhydrostatic loading of brain parenchyma in infants, resulting in mild, nonprogressive macrocephaly.

Brain↗
PubMed1978

Pre- and postoperative cerebrospinal fluid absorption studies in patients with myelomeningocele shunted for hydrocephalus.

Nine infants with myelomeningocele and hydrocephalus had cerebrospinal fluid formation and absorption studies before insertion of a ventriculoperitoneal shunt. Six were also tested postoperatively. The preshunt formation rate varied from 0.21-0.42 ml.min-1 and the cerebrospinal fluid absorption rate or CSF conductance (Ccsf) varied from 0.008 to 0.031 ml.min-1.mm Hg-1. The postoperative formation rate varied from 0.21 to 0.39 ml.min-1. The postoperative CSF conductance (Ct) was calculated as the sum of Ccsf and the shunt conductance (Cs). The relationship between the Ccsf and Cs curves was determined by matching the sum of these curves to the postoperative data points using the method of least-squares. The data suggests that the shunt may work directly or indirectly to establish a new resting pressure; the latter by stabilizing the sagittal sinus pressure which preoperatively increased concomitantly with the CSF pressure and thus enhanced an already-existing absorption deficit.

Absorption↗
PubMed1976

Hydrodynamics of shunt valves.

A study of differential pressure valves (DPV) used in the treatment of hydrocephalus was undertaken to determine their pressure-flow characteristics and compatability with the antisiphon valve (ASV). DPV could be classified into two groups: low resistance valves (LRV) and high resistance valves (HRV). The LRV maintains intraventricular pressure (IVP) near the closing pressure (CP) of the valve by permitting a high flow whenever CP is exceeded. The HRV regulates IVP by attempting to match inflow with some point on the pressure-flow curve of the valve. These characteristics were lost unless valve outlet pressure was maintained at atmospheric pressure. This could be accomplished by using a proximal DPV with an ASV at the DPV outlet, thus converting the DPV into a gauge pressure valve and preventing the 'siphon effect' seen with the use of a DPV alone.

Cerebrospinal Fluid Shunts↗
PubMed1976

A practical method for measuring hydrodynamics of cerebrospinal fluid.

A method for measuring the formation and absorption rates of cerebrospinal fluid is described which can be carried out relatively rapidly and with a minimum of expensive apparatus. It has been found particularly useful in the evaluation of patients with hydrocephalus.

Cerebrospinal Fluid↗