Quantitative magnetic resonance imaging demonstrates alterations of the lingual musculature in obstructive sleep apnea.

Upper airway musculature is important in the pathogenesis of obstructive sleep apnea. Electromyographic studies of patients with obstructive sleep apnea demonstrate increased activity of upper airway dilator muscles. Biopsy studies of these muscles show both adaptation and muscle injury. In this study we utilized quantitative magnetic resonance imaging to characterize changes in the upper airway musculature of patients with obstructive sleep apnea. This technique provides measurements of the T2 relaxation times of upper airway muscles (genioglossus, geniohyoid, sternohyoid/sternothyroid) spatially localized to submillimeter resolution. Our results demonstrate that the mean T2 values of genioglossus (p = 0.04) and geniohyoid (p = 0.06) differ between the apneic and control groups, while the values for the sternohyoid/sternothyroid muscles (p = 0.6) are similar between groups. In both apneics and normals respectively the T2 values for the genioglossus (p = 0.0003, 0.0001) and geniohyoid (p = 0.0054, 0.001) were significantly greater than for the sternohyoid/sternothyroid muscles. The changes observed are compatible with the hypothesis that there is increased edema and possibly increased fat content of the tongue muscles in patients with obstructive sleep apnea.

Modafinil decreases hypersomnolence in the English bulldog, a natural animal model of sleep-disordered breathing.

The English bulldog is a natural model of sleep-disordered breathing (SDB). This condition is marked by 1) hypersomnolence and 2) disordered breathing episodes that are most frequent and severe during rapid eye movement (REM) sleep. Modafinil has been found to increase arousal levels in animals and decrease excessive daytime sleepiness in humans. Therefore, in this study we focused mainly on the effects of the drug on total sleep time and sleep latency and secondarily assessed its effect on REM SDB. Five English bulldogs were implanted with subcutaneous electroencephalographic/electrooculographic (EEG/EOG) electrodes and instrumented with respiratory oscillation belts to measure abdominal and rib cage movements and an ear oximeter to measure saturation. The dogs were studied for approximately 8 hours each subsequent day on two consecutive days. On the first day, they received the vehicle dimethyl sulfoxide (DMSO) i.v. as a control. On the following day they received 10 mg/kg body weight of modafinil i.v. dissolved in the DMSO vehicle. Our findings indicate that modafinil significantly alleviates hypersomnolence (p < 0.05) in the bulldog, as evidenced by dramatically decreased mean total sleep time (from a control value of 50.5% to 8.3% with the drug) and increased mean sleep latency (from a control value of 71.0 minutes to a value of 346.6 minutes with the drug). We obtained limited data on the effect of modafinil on SDB because the drug either greatly diminished or entirely eradicated REM sleep in all five dogs.

Neurofibromatosis 1 and osseous fibrous dysplasia in a family.

We report on the cosegregation of neurofibromatosis 1 (NF 1) and osseous fibrous dysplasia in a family. The father and 3 children by 2 women are affected. A fourth child had neither NF 1 nor osseous fibrous dysplasia. All 4 affected individuals had NF 1, i.e., café-au-lait spots in 4, neurofibromata in 4, Lisch nodules in 3, macrocrania in 3, scoliosis in 2, and curvature of the long bones in 2. Each demonstrated various fibroosseous lesions of the skeleton including non-ossifying fibromas in 3 and both non-ossifying fibromas and fibrous dysplasia in one. This pattern suggests that the fibrous bony lesions are a component of NF 1 in this family. Alternatively, a mutant gene resulting in the fibrous changes in bone could be linked to the gene for NF 1. Another possibility is the coincidence of the 2 non-linked traits segregating in the same family.

Quantitative magnetic resonance imaging of upper airways musculature in an animal model of sleep apnea.

Electromyographic studies of patients with sleep apnea and of the English bulldog, an animal model of sleep apnea, indicate that there is increase activity of the airways dilator muscles. The muscles, when biopsied, show both adaptation and muscle injury. In this study we have utilized quantitative magnetic resonance imaging to characterize changes in the upper airway musculature of the bulldog in vivo. The imaging procedure utilized provided a quantitative measurement of the T2 relaxation times of airway muscle (geniohyoid, sternohyoid, sternothyroid, thyropharyngeus, and hyopharyngeus) and nonairway muscles spatially localized to submillimeter-resolution levels. Quantitative differences between the medians and distributions of T2 relaxation times of airway vs. nonairway muscles were demonstrated. These differences were related to the degree of sleep-disordered breathing. The changes observed are compatible with the hypothesis that there is both increased edema and fibrosis in upper airway muscle in sleep apnea.

Quantification of cerebral ventricular volume in English bulldogs.

Quantitative measurement of cerebral ventricle volume of eight English bulldogs was performed using magnetic resonance (MR) imaging. The mean ventricular volume was 14.8 ml. with a range of 8.6 ml.-38.1 ml. The mean ventricular volume of two beagles was 2.2 ml with a range of 0.7 ml.-3.7 ml. The percent of intracranial volume occupied by ventricle was found to be significantly larger in bulldogs (14.0%; S.D. = 7.9%) than in beagles (Range = 1.0-4.8%). The relationship between the percent of intracranial volume occupied by ventricle and measurements of body weight, age, sex, and various measures of skull anatomy of the bulldog was also determined. The relationship between ventricular volume and neurologic dysfunction was examined. There was a possible trend between high percent of intracranial volume occupied by ventricle and low body weight. This study will serve as a pilot study for examining the relationship between ventricular volume and neurologic disease in bulldogs.