Though the observation of LDH in CF has so far not been the clinical focus of the literature, and though the increased rate of LDH might also be coincidental, this special association seems clinically plausible. In a population-based epidemiological study of persons older than 30 years of age, the prevalence of radiologically-proven LDH with typical clinical symptoms was found to be 1.9% in men and 1.3% in women, with lower percentages in the age cohort of 30 to 44 years of age (men 1.0%, women 1.0%) [
8]. At the age of about 20 years (the approximate age of our three patients at diagnosis) and in adolescence in general, LDH is extremely rare. This age distribution was also observed in people presenting to hospital for LDH surgery [
9]. Pediatric cases only represent a marginal proportion (0.5% to 6.8%) of all LDH [
10]. We hypothesize that the prevalence of 6.5% in our clinic population is due to CF-specific characteristics. Back pain in patients with CF is primarily of a musculoskeletal origin [
11]. Frequent coughing can cause muscle splinting and musculoskeletal pain syndromes. The more the disease progresses, the more patients suffer from chronic coughing, often in spite of still-sufficient lung function parameters. Epidemiological studies clearly hint at the association of chronic cough and herniated lumbar inter-vertebral disc or sciatica due to widespread spondylotic changes of the lumbar spine [
12]. Due to malnutrition and malabsorption syndromes compression fractures can occur in patients with osteoporosis as a result of the mechanical power of coughing, with peak cough expiratory flow rates ranging up to 700L per minute [
13]. Patient 3 had a LDH with neurological deficits (paralytic symptoms) about six months before her death as a result of respiratory failure. A neurosurgical decompression operation was not performed as a result of the bad lung function. The accelerated process of lung deterioration was thought to be influenced by the limited ability to perform adequate respiratory therapy following the LDH. For example, it was not possible to perform reflectory respiratory treatment to its full extent, as well as some mucus mobilization maneuvers involving intensified compression techniques during assisted autogenous drainage and jumping on a trampoline or a pezzi ball. Opioids may also interfere with mucus drainage by a reduction of respiratory power, especially in higher doses. In addition to the physical aspect, the psychological burden on the patients with CF is extremely complex [
14]. Patients with CF suffer from a chronic disease, inevitably leading to premature death respective to a high degree of morbidity. A reduced quality of life, ineffective coping strategies [
15] and physical impairments increase the risk for anxiety and chronic depression in patients with CF [
16]. Chronic painful physical conditions can increase the severity and duration of a depressive mood [
17].
Vice versa, it is well documented in the literature that psychological factors play a key role in the pain perception process and the chronification of back pain [
18]. The resulting chronic muscular imbalance and pathological muscular hypertension may be the basis for disc protrusion and disc rupture. Additionally, studies based on clinical [
19] and experimental [
20] data show that the risk for LDH is significantly increased in cases with a positive family history.