It is not unusual for DLCO to be reduced out of proportion to forced expiratory volume in 1 second (FEV1). Reduction in DLCO and increase in residual volume are generally considered to be LAMs earliest physiologic manifestations.Cardiopulmonary exercise testing in a much larger cohort of patients with LAM revealed a reduced maximal oxygen consumption (VO2 max) and anaerobic threshold in 217 patients. Exercise-induced hypoxemia was found even in patients who did not have resting abnormalities in FEV1 and DLCO. In most patients, exercise was thought to be ventilation limited, owing to airflow obstruction and increased dead-space ventilation.Disease progression is usually accompanied by a progressive obstructive ventilatory defect. Decline in FEV1 is the most commonly used parameter to monitor disease progression. Although resting pulmonary hypertension appears to be unusual in LAM, pulmonary arterial pressure often rises with low levels of exercise, related in part to hypoxemia. One study reported an increase in intraparenchymal shunts in dyspneic patients with LAM, which may contribute to resting and exercise hypoxemia. Pathology
Grossly, LAM lungs are enlarged and diffusely cystic, with dilated air spaces as large as several centimeters in diameter. Microscopic examination of the lung reveals foci of smooth muscle-like cell infiltration of the lung parenchyma, airways, lymphatics, and blood vessels associated with areas of thin-walled cystic change. LAM lesions often contain an abundance of lymphatic channels, forming an anastomosing meshwork of slit-like spaces lined by endothelial cells.
However, it is uncertain whether oral sex would directly transmit the virus or activate the dormant virus that was transmitted at childbirth.In general, physicians are unsure why only certain people who have been exposed to the HPV types implicated in the disease develop laryngeal papillomatosis. In the case of the juvenile form of the disease, the likelihood of a child born of an infected mother developing laryngeal papillomatosis is low (between 1 in 231 to 1 in 400), even if the mothers infection is active. Risk factors for a higher likelihood of transmission at childbirth include the first birth, vaginal birth, and teenaged mother.Three major risk factors affect the acquisition of the juvenile variant. These include:
Birth history (e.g., increased time spent in vaginal delivery) and the presence of HPV in the vaginal canal. It is important to note that it is still uncertain whether caesarean delivery is a protective factor. Genotype of the HPV (e.g., HPV-11)
Individual factors (e.g., being younger when diagnosed, which may be due to a less developed immune system). Diagnosis
Laryngeal papillomatosis can be diagnosed through visualization of the lesions using one of several indirect laryngoscopy procedures. In indirect laryngoscopy, the tongue is pulled forward and a laryngeal mirror or a rigid scope is passed through the mouth to examine the larynx. Another variation of indirect laryngoscopy involves passing a flexible scope, known as a fiberscope or endoscope, through the nose and into the throat to visualize the larynx from above.