Biomedical subjects
Publications and source records attributed to R I Davidson.
A modification of a hemostatic clip applier is described that can apply clips at right angles to the plane of the handles. This device may be particularly useful in certain neurosurgical settings where use of the conventional clip applier is difficult. This device also prevents overcompression of clips.
The objective of this study was to assess the use of saline microbubbles as a sonographic contrast medium in monitoring abscess drainage. Seven abscesses were localized and drained with sonographic guidance. Four were in the brain and three were small abscesses in the liver, the subhepatic region, and the pancreas. After aspiration of the purulent material, irrigation with saline produced a highly echogenic sonographic pattern that was free of artifacts and distinctly different from the abscess contents and capsule, and the surrounding parenchyma. In one case, previously unsuspected loculation was detected, requiring repositioning of the needle for complete drainage. All abscesses were resolved and no untoward effects, such as sepsis, were encountered. In one additional patient, microbubble sonographic evaluation was used to monitor the progress of an abscess in which a percutaneous catheter was placed. Saline microbubbles may be used as a sonographic contrast medium to monitor sonography-assisted abscess drainage.
We describe a 36-year-old woman with a thoracic vertebral osteochondroma who presented with radicular leg pain. This benign tumor is uncommon in the vertebral column, and radicular pain is an unusual manifestation of a thoracic spinal lesion. Myelography and computed tomography aided in diagnosis; surgical resection resulted in an excellent clinical response.
Two modifications of the Frazier suction device are described: a removable distal retractor that is clipped to a modified suction tip and a coupling device that decreases counter-rotational torque.
Transient focal cerebral ischemia may occasionally be due to distal embolization of a clot from an unruptured intracranial aneurysm. Follow-up data in 12 such patients revealed no ischemic strokes, subarachnoid or parenchymal hemorrhages in a mean follow-up period of 6.5 years. The aneurysms ranged in size from 2 to 12 mm in diameter, and only two were larger than 10 mm. Two patients had clip ligation of the aneurysm, five patients were given platelet antiaggregation therapy, one was given oral anticoagulants after aortic valve surgery, and four had no specific therapy. The prognosis for unruptured aneurysms presenting with transient focal ischemia was good, regardless of therapy.
An 8-year-old boy presented in coma and was found to have a massive posterior fossa hemorrhage on computed tomographic scan. Autopsy disclosed a large cerebellar hematoma within a mixed glioma containing both juvenile pilocytic astrocytoma and oligodendroglioma. It is postulated that the hemorrhage originated from the oligodendroglial component of the tumor.
A hand-held double-bladed retractor has been designed in the form of a cross-action bayonette. It acts to retract both lips of an incision simultaneously. The device can be adapted for other uses.
The light and electron microscopic features of a medullomyoblastoma arising in the cerebellar vermis of a 3-year-old boy are described. Differentiation along both glial and neuronal lines was present in the medulloblastoma component of the tumor. Astrocytic differentiation was confirmed by the observation of compact bundles of 8 to 10 nm glial filaments in cellular processes on ultrastructural examination, and by positive immunostaining for glial fibrillary acidic protein (GFAP). Neuroblastic differentiation was suggested by the demonstration of axon-like processes on silver impregnation, and ultrastructurally by the observation of microtubules, dense-core and clear vesicles, and rare synapse-like structures within cytoplasmic processes. The presence of both primitive and well-differentiated striated muscle fibers in the tumor was confirmed by the demonstration of thick and thin myofilaments and Z bands on electron microscopy, and by positive immunostaining for myoglobin. These findings clearly establish the presence of both neuroectodermal and rhabdomyoblastic components in this neoplasm, and thus set it apart from the pure rhabdomyosarcomas, which may also occur in the cerebellar vermis in children. This case also illustrates the usefulness of electron microscopy and immunohistochemistry in the diagnosis and histogenetic evaluation of primitive or poorly differentiated small cell tumors of the central nervous system.
Intra- and extraventricular subarachnoid spaces in children were studied by high-resolution computed tomography. Scans were reviewed of 34 patients who were selected as highly likely to have normal scans. Sizes of the ventricular system and the seven extraventricular subarachnoid compartments were analyzed and graded on a subjective scale from 0 (not visible) to 4 (markedly enlarged). Data were also analyzed by age group (greater or less than 2 years of age). The subarachnoid spaces were found to be both larger and more variable in size before the age of 2 years and to be quite uniform thereafter. Based on these findings, it is inadvisable to base specific diagnoses during the first 2 years of life solely upon modest enlargement of the subarachnoid spaces.
A 31/2-year-old child with a bilateral chronic subdural hematoma due to battering suffered a recurrence on one side. She was treated successfully with a subdural-pleural shunt. Two months later, she returned with severe respiratory embarrassment due to what we think was a cerebrospinal fluid hydrothorax. The maintenance of her earlier neurological recovery was confirmed, and her hydrothorax was cured by removing the shunt. No hydrocephalus ensued.
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Intramedullary spinal cord metastases are rarely the presenting manifestation of a previously undiagnosed neoplasms. We report such a case in which a subacutely progressive motor and sensory spinal cord syndrome was the initial problem. The differential diagnosis and the difficulties in distinguishing intramedullary from extramedullary mass lesions are discussed. The special features of tumors of the lung and their predilection for metastasis to the central nervous system are considered.
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Few reports have described an association between cerebral transient ischemic attacks (TIAs) and unruptured cerebral aneurysms. This study presents seven patients with TIA who had aneurysms in a vascular distribution appropriate to their clinical symptoms. In three patients, angiographic evidence of embolization was present distal to the aneurysm without apparent cardiac or extracranial arterial source for the emboli. The most reasonable pathogenesis for TIA in a patient with an associated saccular aneurysm would be thrombosis of the aneurysmal sac with subsequent embolization. However, subarachnoid blood can cause permanent focal intracranial narrowing, and this appeared to be a factor in at least one patient. The results imply that patients with symptoms of TIA should have their intracranial arterial circulation visualized as part of the diagnostic evaluation.
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Six of a series of 90 patients with hydrocephalus in the first two decades of life were adolescents. Four of these patients had acute symptoms that were superimposed on a baseline of a marginally functional cerebrospinal fluid circulatory system. All 6 patients were believed to have congenital etiologies for their hydrocephalus despite its clinical presentation in the second decade of life.