Catamenial Pneumothorax: Review of Current Findings
Kelly E. Wallis
April 17, 2003
Catamenial Pneumothorax: Reveiw of Current Findings
INTRODUCTION
Catamenial pneumothoracies are defined as, “a recurrent syndrome of pneumothorax that occurs between 48 and 72 hours after menstruation” (Cowl, Dunn & Deschamps, 1999, pg 1414). It is a rare condition with unknown causes; and is characterized by the recurring accumulation of air in the chest cavity during menstruation (Cowl et al., 1999). This syndrome was first described by Maurer and Colleagues in 1958 and was formally named in 1972 by Liddington and Colleagues. Catamenial Pneumothoracies account for 2.8 - 5.6 % of all spontaneous pneumothorax episodes in women (Blanco et al., 1998). It mainly affects women between the ages of 30 and 40 years, and the pneumothoracies are predominantly right sided, occurring in 90 - 95% of cases (Blanco et al., 1998). The diagnosis of this syndrome is difficult as it requires multiple pneumothoracies along with the recognition of a connection to the patients menstrual cycle. As a result there have only been approximately 200 cases documented in international literature to date. The intent of this paper is to review the current research and its applications to this pathology.
EPIDEMIOLOGY
A pneumothorax is defined as the accumulation of gas in the pleural space. This gas causes the separation of the visceral and parietal pleura, and often leads to lung collapse and atelectasis (DesJardins & Burton, 2002). A spontaneous pneumothorax is a pneumothorax that occurs suddenly and without an obvious cause (DesJardin & Burton, 2002). Spontaneous pneumothoracies are a common medical problem, with a yearly incidence of approximately 8600 cases in the United States (Carter & Ettensohn, 1990). They occur predominantly in males and have a male: female occurrence ratio of 4-10: 1 (Carter & Ettensohn, 1990). There are two main categories of spontaneous pneumothoracies: primary and secondary. Primary pneumothoracies are those, which occur in the absence of an underlying lung disease. They have a peak incidence in persons 16 - 25 years of age and are common in tall thin men (Carter & Ettensohn, 1990). Secondary pneumothoracies, which occur most often between the ages of 55 - 65 years, are a result of an underlying lung pathology (Carter & Ettensohn, 1990).
In most cases the treatment for these pneumothoracies is based on the degree of lung collapse present (DesJardins & Burton, 2002). With a small pneumothorax of less than 20 % collapse, the patient is treated with bed rest and decreased physical activity (DesJardins & Burton, 2002). With a pneumothorax of greater than 20 %, the intrapleural gas must be evacuated, either by needle aspiration or chest tube insertion, with or without suction (DesJardins & Burton, 2002). Oxygen therapy may be employed to treat hypoxemia and to decrease the patient’s work of breathing and myocardial work. Hyperinflation techniques may also be used to improve and/or prevent any atelectasis resulting from the pneumothorax. In very severe cases, mechanical ventilation may be initiated to maintain adequate ventilation (DesJardins & Burton, 2002).
CLINICAL FEATURES
Catamenial Pneumothoracies are a subset of the primary pneumothorax category. The most common signs and symptoms, as with most spontaneous pneumothoracies, are chest pain and dyspnea (Blanco et al., 1998). Some patients have also complained of right-sided shoulder pain. This pain has a gradual onset that may range from months to years and is often associated with menstruation (Redwine, 1993). The right-sided shoulder pain has been described as, “coming from deep within the shoulder” (Redwine, 1993, pg 2) and as “radiating from the right chest” (Redwine, 1993, pg 2). In some cases the pain has been reported to spread down the upper right arm and up into the right side of the neck (Redwine, 1993). The risk factors for this syndrome include a family history of pelvic endometriosis (Tripp, Thomas & Obney, 1998), although pelvic endometriosis has only been identified in 22 - 37% of patients diagnosed with catamenial pneumothorax (Cowl et al., 1999).
The diagnosis of catamenial pneumothorax is usually based on either the chest pain associated with the start of menstruation, or a history of recurring pneumothoracies that are predominantly right sided and coincide with the onset of menstruation (Tripp et al., 1998).
PATHOGENESIS
Four theories currently exist to explain the pathology of Catamenial pneumothorax. The first involves the elevated prostaglandin levels that occur during menstruation. Of significant interest is the prostacyclin F2 , which causes severe vasospasm and bronchospasm (Akal & Kara, 2002). It is believed that this leads to the rupture of alveoli and results in a pneumothorax (Fonseca & Bethesda, 1998). The second theory is simply the spontaneous rupture of sub- pleural blebs due to the hormone changes occurring with menses that leads to a pneumothorax (Nwosu et al., 2000). Figure 1 is a thorascopic photograph of an unruptured bleb on the apical surface of the lung (Roberts, Redan & Reich, 2002).
Fig. 1 Thorascopic view of bleb on the right upper lobe of the lung.(Roberts et al., 2002)
The main problem with the first two theories is that they do not explain the predominant right-sided nature of the syndrome. More specifically of the second theory, on laparoscopic investigation many patients had no signs of burst or unburst blebs on their lungs.
The third explanation is known as the Anatomic Model, and it involves the mucus plug that sits in the cervix separating the peritoneal cavity from the atmosphere. During menstruation this mucus plug is absent and this allows air to migrate into the peritoneal cavity. It is believed that from here this air enters the chest cavity by way of congenital diaphragmatic fenestrations and causes the lung to collapse.
The main problem with this theory is that fenestrations are only seen in 19 - 33 % of all catamenial pneumothorax cases and therefore cannot be considered the singular cause of the syndrome (Cowl et al., 1999) . The fourth theory is known as the Metastatic Model, and involves endometrial implants. In this model, the endometrial tissue makes its way from the pelvis to the chest cavity in one of two ways, either up through congenital diaphragmatic fenestrations or via micro-embolism through the pelvic vein. Both modes of travel result in the movement of endometrial tissue into the thorax where it implants itself either on to the lung parenchyma, where it causes local defects, or onto the diaphragm itself. This theory has similar support to the Anatomic Model, with 23 - 35% of cases presenting with pleural and diaphragmatic endometrial implants, and therefore is not necessarily the definitive cause of the syndrome (Fonseca & Bethesda, 1998).
Endometriosis affects approximately 10 - 15% of the menstruating female population (Berkow, 1997), and is defined as a non- malignant disorder in which functional endometrial tissue is found outside of the uterus. It commonly affects women between the ages of 25 - 44 years. There is a familial tendency towards this, as the incidence of endometriosis is 6% greater in first-degree relatives of women with endometriosis than it is in the general population (Berkow, 1997). Endometrial tissue changes with the changing hormone levels of a woman’s cycle, and this can give rise to holes in the diaphragm in affected women, allowing the passage of air into the thorax with menses. These endometrial implants appear as bluish nodules as seen in Figure 3.
Fig 3. Thorascopic view of diaphragmatic endometrial implants (Roberts et al., 2002)
The presence of thoracic endometrial tissue can also lead to a “check valve” obstruction of the terminal bronchioles causing hyperinflation and alveolar rupture during menstruation (Carter & Ettwnsohn, 1990). Both of these conditions will lead to lung collapse.
With both the anatomic and metastatic theories, the right-sided predominance of catamenial pneumothorax is explained by the differing anatomy of the two sides of the abdomen. The liver, on the right side of the diaphragm, creates a piston action that helps to move air through that side of the diaphragm (Roth, Alifano, Schussler, Magdaleinat & Regnard, 2002), whereas on the left side of the diaphragm there is no such structure to aid in this. This is believed to account for the much higher incidence of right-sided pneumothoracies in catamenial pneumothorax.
In further support of the metastatic model of catamenial pneumothorax is the research that has been done on a pathology called TES, or Thoracic Endometriosis Syndrome. TES has a peak incidence between the ages of 30 - 34 years similar to that of catamenial pneumothorax, and has also been found to have up to a 90% right-sided predominance (Joseph & Sahn, 1996). The most common presentation of TES, occurring in 80 of 110 patients diagnosed, is spontaneous pneumothorax (Joseph & Sahn, 1996). Of the 80 patients diagnosed with TES and spontaneous pneumothorax, 61 underwent a thoracic exploration, either via thoracotomy or thoracoscopy. The findings are summarized in Table 1.
_______________________________________________________________________
TABLE 1
Pathological Findings in Patients With TES and Spontaneous Pneumothorax_____________
# Underwent
# of Patients Thoracotomy/ Pleural Diaphragmatic Cysts/Blebs No Findings
Thoracoscopy Endometriosis Defects
________________________________________________________________________
80 61(76%) 8(13%) 16(26%) 14(23%) 15(25%)
________________________________________________________________________
(Joseph & Sahn, 1996)
The importance of these findings on investigation is the fact that they demonstrate the many pathological findings possible with diaphragmatic endometriosis. These four main pathological findings encompass three of the four explanations for catamenial pneumothoracies. This may point to diaphragmatic endometriosis as being the main cause of catamenial pneumothorax because of the variety of ways that it may present itself on investigation.
MANAGEMENT AND TREATMENT
A variety of treatments for catamenial pneumothorax have been tried over the years ranging from non-invasive hormonal treatment to the invasive diaphragmatic resection. There have been differing amounts of efficacy with these various treatments and there are risks and benefits with all of them. The two main categories for treatment options are medical and surgical. The medical treatment options are mainly hormonal therapies that are aimed at suppressing the activity and growth of endometrial tissue present in the chest (Joseph & Sahn, 1996). This is done by suppressing ovulation and estrogen release. The three hormonal treatments that have been tried to date are testosterone derivatives, oral contraceptives, and GnRH agonists.
Testosterone derivatives such as Danazol work to suppress ovulation and estrogen release by suppressing the function of the gonadotropins (Joseph & Sahn, 1996). This suppression is said to produce an estrogen blockade, therefore preventing estrogen from reaching the endometrial tissue ( Tripp et al., 1998). The side effects of these drugs include weight gain, fluid retention, fatigue, acne, hot flashes, facial hair growth and deepening of the voice (Roberts et al., 2002). The efficacy of this treatment has not been that good, as it has only prevented recurrence in approximately 50% of those treated.
Oral contraceptives contain either a combination of progestin and estrogen or just progestin alone (Berkow, 1997). They function by suppressing ovulation, and have been found to be only approximately 50% effective at preventing recurrence of pneumothorax (Joseph & Sahn, 1996). The side effects of these drugs include abdominal swelling, breast tenderness, increased appetite, water retention, nausea, spotting and deep vein thrombosis (Berkow, 1997).
GnRH agonists are another option for the treatment of catamenial pneumothorax. They function by initially stimulating the release of gonadotropins from the pituitary gland and then suppressing their release when administered for more than a couple of weeks (Berkow, 1997). This type of drug allows the patient to preserve their reproductive potential (VanSchil, Vercauteren, Vermiere, Nackaerts & Van Marck, 1996) and has been very successful in preventing pneumothorax recurrence when given for prolonged periods of up to one year (Tripp et al., 1998). These drugs produce a medically induced amenorrhea and can often lead to hypoestrogenia (Nwosu et al., 2000), hot flashes and bone loss (Roberts et al. 2002). Some examples of GnRH agonists are Lupron, Triptoreline, Busereline and Goserelin. Most are given as approximately 3.5mg dose subcutaneously once monthly.
Surgical treatment is the other option when managing catamenial pneumothorax. Treatment using a surgery can be achieved with a variety of methods including pleurodesis/pleurectomy, hysterectomy, thoracoscopic or thoratomic diaphragmatic and endometrial resection, along with bleb and apical resection where applicable.
Pleurodesis is a procedure where the pleural lining of the lung is scarred either mechanically or chemically to prevent further pneumothoracies. Chemical pleurodesis is done by administering tetracycline, minocycline or talc as a poudrage intrapleurally (Joseph & Sahn, 1996). It has been found to be an effective method of preventing recurrent pneumothoracies but does not treat the root of the problem. It is for this reason that it is not often used as a first line treatment for catamenial pneumothorax. It is common for patients treated with this method to still experience chest pain without lung collapse during menses (Joseph & Sahn, 1996). This is a result of the remaining endometrial tissue in the pleural cavity (Carter & Ettensohn, 1990).
Hysterectomies with bilateral oopherectomy are another option for treatment that is most often used in women outside of their childbearing years. It is effective for some time because it eliminates the main estrogen producing area of the body, but the hypoestrogenia that results can lead to problems when add back estrogen therapy is started . This may reactivate the dormant endometrial tissue causing a recurrence of catamenial pneumothorax (Joseph & Sahn, 1996).
There are two methods for investigating the causes of catamenial pneumothorax, thoracotomy and thoracoscopy. Thoracotomy is the more invasive of the two and involves the surgical opening of the chest cavity. The less invasive thoracoscopy is the newer, preferred method using three small incisions and a fiber optic video camera’s assistance. It is the preferred method because it allows for a complete investigation of both the chest wall and the diaphragm (Roth et al., 2002).
Once inside the chest there are a few different surgical options depending on what is found. If endometrial implants are found, their resection should be performed to limit further endometrial spreading. If they occur in the diaphragm, than a resection of the diseased area of the muscle should be performed to allow it’s complete closure. This treats the mechanism of catamenial pneumothorax by both removing the endometrial tissue and by closing all areas for air entry into the chest cavity (Roth et al., 2002). The other surgical options include bleb resection where they are found to restore lung patency, and apical resection where required (Tripp et al., 1998). Pleurodesis or a pleurectomy may also be performed at this time when it is believed to be the best option for preventing further recurrences (Tripp et al., 1998).
It has been found that overall the surgical treatment of catamenial pneumothorax results in a far lower recurrence rate than the hormonal treatment does (Tripp et al., 1998). At six months post treatment, only 50% of medically treated patients were free of recurrence compared to approximately 95% of the surgically treated patients. By one year 75% of surgically treated patients had experienced no recurrences while only approximately 40% of the medically treated patients were still free of recurrence, as shown in Figure 4 (Tripp et al., 1998).
Fig 4. Recurrence of pneumothorax in medically vs. surgically treated patients with catamenial pneumothorax. Surgically treated patients had a lower recurrence rate at both 6 and 12 months (Tripp et al., 1998).
In most cases of catamenial pneumothorax the initial pneumothorax episodes are treated in the same manner as any spontaneous pneumothorax. The next step tends to be using a GnRH agonist or other forms of hormonal treatment to prevent recurrence. It is only when these treatments fail that more invasive thoracoscopic procedures are used to obtain biopsies, perform pleurodesis, and resect endometrial areas (Van Schil et al., 1996). The decision on the treatment of catamenial pneumothorax needs to be decided on a case-by-case basis, to take into account each individual’s needs along with their age, fertility status and pathological findings (Nwosu et al. 2000). The risks and benefits of the different treatments must be taken into account for each patient along with their individual tolerance for the possible side effects of each treatment option.
CONCLUSIONS
Catamenial pneumothorax is a complicated syndrome of recurrent pneumothoracies with no specifically proven etiology. For this reason, no single treatment option will be adequate in treating all of the patients’ needs. To add to this, the diagnosis is sometimes just as difficult as deciding the course of treatment, as multiple episodes of pneumothorax usually occur before the syndrome is recognized. Therefore the treatment must be based on any and all pathological findings from clinical investigation to prevent further episodes, and by using supportive treatments to manage each episode as it occurs.
This syndrome has become a more common diagnosis in the past 10 years, and this is likely due to the increased awareness of its existence and the research that has been carried out to date. Though quite a few significant discoveries have been made regarding both the causes and possible treatments of this syndrome, much more research is still necessary in order to treat it in a more effective and timely manner.
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