Biomedical subjects
Publications and source records attributed to L Mayfrank.
We report the cytogenetic findings in two meningiomas from a child presenting with multiple meningiomas. In contrast to the chromosomal profile of adult meningiomas, both tumors studied revealed excess of chromosomes in addition to monosomy 22. This difference is remarkable considering several reports indicating that childhood meningiomas behave differently and have a worse prognosis than those in adults.
CT examinations of 11 consecutive patients with neurofibromatosis type 2 (NF-2) revealed non-tumoral intracranial calcified deposits in seven cases. Abnormal calcification of the choroid plexus was found in six cases. Calcification in the cerebellar hemispheres was observed in four cases. In two cases nodular calcifications on the surface of the cerebral hemispheres were detected. Our findings and the data in the literature show that non-tumoral calcifications of different locations can be regarded as part of the NF-2 syndrome.
Clinical and genetic data of 10 patients with neurofibromatosis 2 (NF-2) are presented. Interestingly, no family history of neurofibromatosis was detectable in any of them, which indicates that these are sporadic cases of NF-2, most likely due to a new mutational event. According to our own results and the data in the literature, sporadic cases of NF-2 are clinically characterized by a high incidence of multiple meningiomas and spinal tumors in addition to the bilateral occurrence of acoustic neurinomas. The clinical heterogeneity of NF-2 is pointed out and the possible existence of different forms of this disease is discussed.
The surgical indication for spontaneous cerebellar hemorrhage is not as controversial as the operative management of intracranial hemorrhage. Timing of the operation is crucial: intervening too early can produce an additional strain on the patient and an increased risk, while waiting too long to evacuate the hematoma can be fatal. This dilemma may be a factor in the relatively high mortality and morbidity rates following both operative and conservative treatment that have been reported in the literature (42.5% and 30%, respectively). In long-term studies on 14 patients, the authors have shown that stereotactic puncture and fibrinolysis for cerebellar hemorrhage is a valuable alternative to treatments used currently. The method consists of computerized tomography (CT)-guided stereotactic puncture and partial evacuation of the hematoma. After fibrinolysis with urokinase, the residual hematoma can be completely evacuated via a catheter introduced into the cavity of the hematoma. Only one of the 14 patients died in the direct postoperative phase; the remaining patients were enjoying a good to very good quality of life 6 months after the acute event. Two patients subsequently died as a result of pneumonia and cerebral infarction, respectively; both conditions were unrelated to the hemorrhage. The authors conclude that the CT-guided stereotactic method is simple, effective, and safe, and can be applied to patients of any age.
We have studied a meningioma and an acoustic neurinoma of a patient with central neurofibromatosis. In the meningioma cells, one chromosome 22 was replaced by an almost metacentric, bisatellited marker chromosome that appeared monocentric after CBG-staining. In situ hybridization with a chromosome 22 centromere specific DNA probe (p22hom48.4) revealed specific signals in the pericentromeric region of the marker chromosome, indicating the presence of at least the short arm and the centromere of chromosome 22. The pericentromeric localization of the hybridization signals suggest the marker consists of an isoformation of the short arm of chromosome 22, resulting in a monosomy for the long arm of chromosome 22. In contrast to these findings in meningioma cells, no chromosomal abnormality could be detected in acoustic neurinoma cells. Our findings provide further evidence that loss of genetic material on the long arm of chromosome 22 is associated with the development of central neurofibromatosis.
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Two cases of vitamin B12 deficiency caused by gastric atrophy are described. Together with the neuropsychiatric features usually associated with this condition, a downbeat nystagmus syndrome was observed. It is concluded that vitamin B12 deficiency may also result in lesions to those cerebellar or brain-stem structures that are generally assumed to cause downbeat nystagmus.
The differential influence of fixation and directed visual attention on reaction times of goal-directed saccades and especially on the occurrence of express saccades was investigated. In all the experiments the subjects were instructed first to keep their direction of gaze at the center of a translucent screen with or without a central fixation point. When a new stimulus appeared, the subjects had to look at it as soon as possible. In some control experiments the subjects had to direct their gaze to the screen center and simultaneously direct their attention to a peripheral light spot before the target for the saccade appeared. Many express saccades occurred when either active fixation of a central fixation point or attention directed to a peripheral visual target (regardless of its position) was interrupted 200 ms before the target for the saccade appeared. Express saccades were almost completely abolished in the presence of fixation and/or directed visual attention at the moment in which the saccade target appeared. We conclude that express saccades occur if visual attention has already been released at the moment when the target for the saccade appears. This disengagement needs some time which adds to the reaction time.
A case of traumatic synchondrotic disruption in a 15-month-old girl is reported; she was treated with interlaminar wiring of C1-C2 without grafting. Reduction of the dislocation and angulation and stability were achieved without evidence of growth disturbance. However, the child's initial poor neurological status with tetraplegia below the level of C7 remained unchanged. Besides our case, there are only three other cases in the literature of young children primarily operated on for a traumatic odontoid synchondrotic disruption. Even though the dorsal interlaminar wiring of C1-C2 without grafting is an easy and safe procedure even in the very young, the optimal form of treatment for this rare injury is still unsettled.