Waldenstrom macroglobulinemia involving the superior rectus muscle.

PURPOSE: We present the first reported case of Waldenstrom macroglobulinemia in the right superior rectus causing diplopia. OBSERVATIONS: A 72-year-old man with a 6-month history of untreated asymptomatic Waldenstrom macroglobulinemia presented with 2 years of diagonal binocular diplopia that was previously thought to be due to ocular myasthenia gravis. Examination showed mild right proptosis and right hypotropia, and MRI revealed a focal lesion of the right superior rectus muscle. Orbital biopsy was performed, and histopathology showed lymphoplasmacytic infiltration among the skeletal muscle fibers of the rectus muscle. Immunostaining confirmed a B-cell preponderance, along with more extensive staining for IgM than IgG, and in situ hybridization confirmed lambda restriction. These findings corresponded with those of his previous bone marrow biopsy, confirming Waldenstrom macroglobulinemia as the etiology for the extraocular muscle mass. CONCLUSIONS AND IMPORTANCE: Lymphoma of an extraocular muscle is a rare manifestation of orbital lymphoma, and the tumors are usually mucosa-associated lymphoid tissue (MALT) lymphomas (i.e. extranodal marginal zone lymphomas). There are 4 previous reports of lymphoplasmacytic lymphoma of an extraocular muscle; however this is the first reported case of such a lesion in a patient with concurrent Waldenstrom macroglobulinemia at the time of diagnosis.

Variation of respiratory sinus arrhythmia with age.

Respiratory sinus arrhythmia was measured on 24 male subjects whose ages ranged from 21 to 65 yr, using a technique in which respiration was coupled to heart rate, so that there were 6 heartbeats per inspiration and 6 heartbeats per expiration. This voluntary cardiorespiratory coupling reduced the variance of heart rates measured at various points in the respiratory cycle. Fourier analysis was used to obtain the fundamental of heart rate and respiratory volume. A high correlation coefficient (-0.83) was found between percent of variation of heart rate from the average heart rate (PB) and the age of the subject. Linear regression analysis performed on these data produced the equation: PB = 23.2-0.35 (age). Since sinus arrhythmia at the low respiratory frequencies used probably reflects the viability of the cardiorespiratory control systems, we believe this provides a simple noninvasive method for the study of the overall competence of the system responsible for respiratory sinus arrhythmia.