✓ Four patients who developed increased intracranial pressure from ventricular shunt failure suffered a delay in diagnosis because magnetic resonance imaging of the brain did not show ventriculomegaly and because ophthalmic findings were initially overlooked or misinterpreted. None of the patients had the conventional manifestations of shunt failure: severe headache, nausea, vomiting, and depressed consciousness. Three patients suffered marked, permanent vision loss from chronic papilledema. These cases affirm that increased intracranial pressure may occur in shunt dependency without producing either conventional clinical symptoms or signs on imaging of the brain. Because ophthalmic manifestations may be the major clues to diagnosis, and because irreversible loss of vision is possible if these clues are overlooked, consideration should be given to periodic ophthalmological examination of shunt-dependent patients.

✓ The mechanisms previously proposed for the progression of syringomyelia associated with Chiari I malformation of the cerebellar tonsils are controversial, leave many clinical observations unexplained, and underlie the prevalence of different operations currently used as initial treatment. To explore the mechanism of syringomyelia progression in this setting, the authors used anatomical and dynamic (phase-contrast and phase-contrast cine) magnetic resonance (MR) imaging, and intraoperative ultrasonography to examine the anatomy and dynamics of movement of the cerebellar tonsils, the wall of the spinal cord surrounding the syrinx, and the movement of cerebrospinal fluid (CSF) and syrinx fluid at rest, during the respiratory and cardiac cycles, and during Valsalva maneuver in seven affected patients.

在所有患者小脑扁桃体阻挡届e subarachnoid space at the level of the foramen magnum. Syringomyelia extended from the cervical to the lower thoracic segment of the spinal cord. No patient had evidence of a patent communication between the fourth ventricle and the syrinx on anatomical MR images, dynamic MR images, or intraoperative ultrasound studies. Dynamic MR images of three patients revealed abrupt downward movement of the spinal CSF and the syrinx fluid during systole and upward movement during diastole, but limited movement of CSF across the foramen magnum during the cardiac cycle. Intraoperative ultrasound studies demonstrated abrupt downward movement of the cerebellar tonsils during systole that was synchronous with sudden constriction of the spinal cord and syrinx. Decompression of the foramen magnum was achieved via suboccipital craniectomy, laminectomy of C-1 and C-2, and dural grafting, leaving the arachnoid intact. Immediately after surgery, the pulsatile downward thrust of the tonsils and constriction of the spinal cord and syrinx disappeared. Syringomyelia resolved within 1 to 6 months after surgery in all patients.

Observations by the authors suggest the following previously unrecognized mechanism for progression of syringomyelia associated with occlusion of the subarachnoid space at the foramen magnum. The brain expands as it fills with blood during systole, imparting a systolic pressure wave to the intracranial CSF that is accommodated in normal subjects by sudden movement of CSF from the basal cisterns to the upper portion of the spinal canal. With obstruction to rapid movement of CSF at the foramen magnum, the cerebellar tonsils, which plug the subarachnoid space posteriorly, move downward with each systolic pulse, acting as a piston on the partially isolated spinal CSF and producing a systolic pressure wave in the spinal CSF that acts on the surface of the spinal cord. This causes progression of syringomyelia by abruptly compressing the cord and propelling the fluid in the syrinx longitudinally with each pulse, and may be responsible for the origin and maintenance of syringomyelia by the pulsatile pressure waves forcing CSF into the cord through the perivascular and interstitial spaces. Effective treatment occurs when the systolic pressure wave transmitted by the cerebellar tonsils is eliminated by relieving the obstruction to rapid movement of subarachnoid CSF across the foramen magnum. The presence of this mechanism can be detected preoperatively on dynamic MR images and during surgery on ultrasound studies by the pulsatile excursion of the wall of the spinal cord surrounding the syrinx and by its immediate disappearance and the expansion of the syrinx during forced inspiration after decompression of the tonsils. Effective treatment is achieved with bone and dural decompression of the foramen magnum alone, without entering the arachnoid.

Object.This prospective, randomized, placebo-controlled, double-blind trial was undertaken to assess the efficacy of aprotinin in reducing the need for blood transfusions in 39 children undergoing reconstructive craniofacial surgery.

Methods.Two demographically similar groups—a total of 39 patients with a mean age of 1.2 ± 1.2 years—were studied. The efficacy of aprotinin (240 mg/m²administered intravenously over 20 minutes, followed by infusions of 56 mg/m²/hr) was compared with that of an equal infusion of 0.9% saline (placebo).

Patients in the aprotinin group received less blood per kilogram of body weight than patients in the placebo group (32 ± 25 ml/kg compared with 52 ± 34 ml/kg, respectively; p = 0.04). Those patients in whom aprotinin was administered experienced less change in their hematocrit levels during surgery (aprotinin −33 ± 13% compared with placebo −44 ± 9%, p = 0.01). Each patient underwent a transfusion as per study protocol, and there was no significant change in hematocrit levels from the beginning to the end of surgery. The surgical faculty judged blood loss in patients in the aprotinin group to be significantly less than usual (p = 0.03). The use of aprotinin was also associated with reduced blood transfusion requirements during the first 3 postoperative days (p = 0.03). There was no adverse event reported in either the aprotinin or placebo group.

Conclusions.Aprotinin decreased blood transfusion requirements in pediatric patients undergoing craniofacial reconstruction, thereby reducing the risks associated with exposure to banked blood components.