Disturbances of the Autonomic Nervous System in PD Patients

Disturbances of the autonomic nervous system (ANS) are seen in up to 80% of PD patients. In 50% of PD patients these disturbances lead to a significant impairment of quality of life. Basically, all parts of the autonomic nervous system may be affected in PD patients, but impairments of the cardiovascular, gastrointestinal and urogenital system are most frequently reported by the patients. It must be considered, however, that dysfunction of the ANS may occur as part of PD, as a side effect of the medication, as a feature of atypical PD and as a symptom of another unrelated disease such as diabetes. Treatment of the ANS symptoms should always start with optimizing the treatment of the Parkinsonian syndrome. If this does not result in an improvement of the ANS symptoms, a change of the PD treatment or additional specific treatment of the ANS symptoms may be considered. Patients with PD often present with orthostatic hypotension which may be due to central or peripheral autonomic dysfunction. PD patients often lack blood volume and sympathetic control of vasoconstriction. In our lab we investigate these patients with a tilting table and online analyses of blood pressure and heart rate. In addition, we monitor blood pressure and heart rate during a Valsalva manoeuvre. Finally, in many patients we observe insufficient heart rate modulation during deep inspiration and exspiration. Continuous 24-hour blood pressure monitoring revealed blood pressure peaks during the night and low blood pressure at daytime in 8/11 patients with multiple system atrophy and 8/13 of PD patients. Therapy consists of adequate fluid intake, salt tablet supplements, elevation of the head of the bed by 30 degrees and medication such as midodrine, fludrocortisone or L-threo-DOPS. Constipation is also a common problem in PD patients and may lead to altered intestinal drug absorption which is often the reason for motor fluctuations. Most patients improve by dietary modifications and/or addition of a high-fibre diet. In Europe domperidone is another option. Proper Anti-Parkinsonian medication may also improve motor function and allow the patient to become more ambulatory and physically active. Urinary problems are also common in PD. Usually patients present with incontinence and urgency. Detrusor hyperactivity is often found and application of anticholinergics such as tolterodine and oxybutynine is helpful. Sexual problems are often side effects ot the medication, for example hypersexuality after intake of dopamine agonists. On the other hand, many patients complain of impotence and have to use sildenafil. Increased sweating can be treated by ß-blockers and pirenzepine or sage.