Visualization of injected embolic material (polyvinyl alcohol) in paraffin sections with Verhoeff-Van Gieson elastica stain.

Therapeutic embolization of blood vessels is widely used to treat vascular malformations and to preoperatively decrease the size of bulky tumors by creating iatrogenic infarction. Surgical pathologists are often called upon to identify the presence of embolized material in microscopic slides. Polyvinyl alcohol particles are often used as the material for embolization. On hematoxylin-eosin and other routine stains this substance is almost invisible. These particles stain black and can be sharply outlined by using the Verhoeff-Van Gieson stain.

Synovial cysts of the lumbar spine: diagnosis, surgical management, and pathogenesis. Report of eight cases.

BACKGROUND: Synovial cysts are uncommon extradural degenerative lesions associated with symptoms of lower back pain and radiculopathy. Most of these lesions occur in the lumbar spine at the L4-5 level and to a lesser extent at the L5-S1 and L3-4 levels. METHODS: A retrospective study involving eight patients seen by the neurosurgery service from January 1, 1989, to May 30, 1994, was analyzed. The type, duration, and distribution of symptoms were evaluated, along with the patient's age and sex. All patients had lumbosacral spine x rays and magnetic resonance imaging. Four had a computed tomography-myelogram of the lumbar spine. All patients underwent a laminectomy or hemilaminectomy and cyst excision, and all were followed for a minimum of 1 year. The presence of a synovial cyst was confirmed by histopathology. RESULTS: Of the eight patients, seven had dramatic pain relief with five having complete resolution of pain. The single care of persistent pain was found to be due to scar tissue at the operative site. All five cases of preoperative lower extremity weakness showed complete resolution. Dysesthesia was either unchanged or decreased. CONCLUSIONS: Surgery is a safe, effective treatment for patients with lumbar synovial cysts and is the treatment of choice for these lesions.

Surgical "touch artefacts" of the cerebral cortex. An experimental study with light and electron microscopic analysis.

In surgically excised brain tissue a very common artefact, unrelated to the presence or absence of a genuine pathological process, involves the water content of cortical neurons. Nerve cells may show massive watery swelling of both their cytoplasm and nuclei or conversely may become shrunken and dark-staining. The most important aspect of this alteration is that it may lead to mistaken histopathological interpretation, but the question also arises whether such changes, presumably caused by exposure, touch, pressure or the combination of all 3, in the living patient, would persist after surgery and would eventually result in irreversible damage to the involved neurons? Thirty rats were operated in this experiment: craniotomy and opening of the dura mater was done over one convexity and slight pressure (uniformly calibrated for all animals) was applied to the exposed cortex. The wound was closed and the animals were sacrificed at various intervals, ranging from immediately after the operation to 6 weeks. The areas that suffered compression were examined by light and electron microscopy. Initial changes included marked watery swelling of neuronal perikarya and nuclei which predominated over pyknotic changes. The changes thus produced were identical with those seen in portions of the cortex excised immediately after pressure was applied to the area in 10 additional rats.(ABSTRACT TRUNCATED AT 250 WORDS)