Occipital nerve block in the management of headache and cervical pain

The origins of chronic headache and the role of the greater occipital nerve in headache syndromes are reviewed. The anatomical pathways and physiological basis of these headaches are discussed with a view to synthesizing some current concepts of headache generation. Studies of occipital nerve blockade for treatment of headaches of various types are assessed and a retrospective analysis of our own experience is presented.     

Mediastinal histoplasmosis granuloma: evaluation with CT

Mediastinal granuloma secondary to histoplasmosis was described in three patients. Computed tomographic scans in each patient demonstrated a large, low-attenuation mediastinal mass crossed by enhancing septae. Other granulomatous diseases may produce similar abnormalities. The differential diagnosis of such lesions was discussed.     

Preferential expression of double-stranded ribonucleic acid in tumor versus normal cells: biological and clinical implications

In an effort to develop a new tumor marker suitable for flow cytometric analysis, we examined the value of double-stranded ribonucleic acid (ds- RNA) measurements using propidium iodide after DN'ase treatment. Cellular ds-RNA content was evaluated both in experimental cell lines and in clinical specimens. Higher levels of ds-RNA were present in tumor cells as compared with normal cells. In tumor cells, fluorescence was intensely localized in the nucleolus and was more diffuse in the cytoplasm. Change of less than 10% in the ds-RNA levels was observed in cell lines as a function of cytokinetic determinants such as cycle phase, culture age, and cycle traverse rate. Tumor differentiation by dimethylsulfoxide resulted in a significant decrease in cellular ds-RNA content. For quantitative comparison of clinical material, a ds-RNA excess was defined in relationship to normal peripheral blood lymphocytes. ds-RNA excess greater than 30% was observed in only one of 34 normal tissues (3%) as compared with 124 of 201 neoplastic tissue samples (62%). This incidence was higher in patients with acute leukemia (76%), high-grade and intermediate-grade lymphoma (75%), and high tumor stage myeloma (83%), as compared with chronic leukemia (20%), low-grade lymphoma (25%), and intermediate or low tumor mass myeloma (43%). Prognostically, a high pretreatment ds-RNA excess in myeloma was associated with a lower remission rate. The persistence of ds-RNA excess in the bone marrow of patients with acute myelogenous leukemia in remission predicted for a shorter remission duration (seven v 22 months; P = .05). We conclude that ds-RNA excess, as readily measured objectively and quantitatively by flow cytometry, may have important diagnostic and prognostic implications for the management of patients with malignant disease.