Automatic analysis of the electromyographic interference pattern. Part II: Findings in control subjects and in some neuromuscular diseases

The electromyographic (EMG) interference pattern (IP) was measured in the biceps muscle of 16 normal male and 17 normal female subjects. The activity, upper centile amplitude (UCA), and the number of small segments (NSS) (defined in a companion paper) were measured from 500-msec epochs of the IP. The normal values of these features were defined separately for men and women by plotting the UCA and NSS values against activity for each epoch and defining an area on these plots, called a “cloud,” that contained more than 90% of the datum points from each study. The mean deviation of the individual datum points from the overall mean values was also calculated for each study. A study in one muscle is considered to be normal if more than 90% of the datum points from that muscle are within the normal clouds and the deviation values are within their normal range. In patients with neuropathy, the characteristic pattern was increased UCA with normal or decreased NSS. In patients with myopathy, NSS was increased and the UCA was normal or decreased. In all studies, the interpretations of the IP from the plots agreed with qualitative assessments of the IP made independently by an electromyographer. The use of these features to understand and quantitate the changes in the motor units produced by disease is demonstrated by serial studies performed in a patient with motor neuron disease.     

Acute renal failure without fibrotic skin changes in progressive systemic sclerosis

Scleroderma renal crisis (SRC) is defined as sudden development of accelerated hypertension, hyperreninemia, and acute renal failure in a patient with progressive systemic sclerosis (PSS). Although the diagnosis of PSS is generally straightforward because of dermal fibrosis, we report 2 patients who had PSS with SRC without the characteristic fibrotic skin changes of scleroderma. PSS should be considered in the differential diagnosis of unexplained acute renal failure and accelerated hypertension even though the cutaneous fibrotic manifestations of the disease may be absent.     

Incidence of retinal detachment following posterior chamber intraocular lens surgery

We examined the three-year incidence of retinal detachment in a consecutive cohort of 4,329 eyes which had cataract surgery with implantation of a posterior chamber intraocular lens between 1979 and 1984. The overall three-year incidence was 1.4%. The three-year incidence for open capsule cases (1.9%) was over twice that for intact capsule cases (0.8%). Axial myopes (axial length greater than or equal to 25 mm) overall were at least three times as likely to develop retinal detachment within three years (3.6%) as eyes with axial lengths less than 25 mm (1.1%). The combination of open capsule and axial myopia increased the three-year retinal detachment risk tenfold over that of the intact capsule in normal length eyes.     

Optimal site for throat culture: tonsillar surface versus posterior pharyngeal wall

To determine the optimal site of throat culture for the detection of potential pathogens by comparing culture results from the tonsillar surface and the posterior pharyngeal wall in children selected for adenotonsillectomy and in children without upper respiratory disease. Cotton culture swabs were taken from the tonsillar surface and the posterior pharyngeal wall of 50 children selected for adenotonsillectomy for symptoms of recurrent tonsillitis and/or adenotonsillar hypertrophy and of 50 children without upper respiratory disease. Potential respiratory pathogens were identified. In the overall group (n = 100), positive culture results were found in 67 posterior pharyngeal wall samples and 47 tonsillar surface samples (P = 0.001). Haemophilus influenzae was the most frequently isolated micro-organism both in the posterior pharyngeal wall and the tonsillar surface samples; 55 and 35%, respectively (P = 0.001). Group A beta-haemolytic streptococci were found in the samples of the posterior pharyngeal wall and the tonsillar surface in 17 and 13%, respectively (P = 0.2). When dealing with patients with sore throat, sampling both tonsillar surfaces is enough for the detection of group A beta-haemolytic streptococci. When detection of other bacteria is also important, such as for research purposes, the posterior pharyngeal wall should be sampled as well.     

Choline: Dietary Requirements and Role in Brain Development

Choline is needed for the maintenance of the structural integrity and signaling functions of cell membranes, for neurotransmission, and for transport of lipids and as a source of methyl groups. Choline can be made de novo in the body, but some individuals must also obtain choline in the diet to prevent deficiency symptoms. A number of environmental and genetic factors influence dietary requirements for choline, and average intakes in the population vary widely. Therefore, certain individuals may be at greater risk of choline deficiency. Choline is critical during fetal development, particularly during the development of the brain, where it can influence neural tube closure and lifelong memory and learning functions.