Could not enroll enough participants, and lost funding.

This research study will be conducted in patients with primary autonomic failure, a disabling condition that is associated with low blood pressure upon standing. These patients are also not able to control for changes in their blood pressure due to a loss of cardiovascular reflexes that are mediated within the brain. The purpose of this study is to determine whether magnetic resonance spectroscopy (MRS), a non-invasive imaging technique, can measure levels of chemicals (neurotransmitters) in the dorsal medulla, a brain area important for control of cardiovascular function, in autonomic failure patients. Importantly, this study will determine whether there are differences in brain chemicals between patients with peripheral versus central origins of their autonomic failure. The hypothesis is that the neurotransmitter profile in the medulla will be intact in patients with peripheral autonomic failure compared to those with central impairment. Overall, this study will provide insight into understanding the mechanisms involved in autonomic failure and will determine whether a single session of MRS imaging can improve the ability to make an accurate diagnosis in these patients. This would lessen the need for more extensive and invasive clinical testing.

Inclusion Criteria:

• Patients with primary autonomic failure who are already participating in the approved Vanderbilt study "Evaluation and Treatment of Autonomic Failure"
• Males and females of all races between 18 and 80 years of age
• Able and willing to provide informed consent

Exclusion Criteria:

• Pregnant women
• Patients with diagnosed Parkinson's Disease or secondary forms of autonomic failure
• Patients with severe claustrophobia
• Patients taking medications known to affect brain neurotransmitter levels [e.g., anti-depressants, barbiturates, benzodiazepines, gabapentin, namenda, sinemet]
• Patients with implanted medical devices [e.g., pacemakers, metal clips, cochlear implants, orthopedic hardware], lead-based tattoos or pieces of metal close to or in an important organ
• High-risk patients [e.g., heart failure, symptomatic coronary artery disease, liver impairment, history of stroke or myocardial infarction]
• Inability to give or withdraw informed consent
• Other factors which in the investigator's opinion would prevent the subject from completing the protocol including significant abnormalities in clinical, mental, or laboratory testing

Primary autonomic failure patients will be recruited from patients already in the hospital participating in the approved protocol "The Evaluation and Treatment of Autonomic Failure." Prospective participants come from several sources including clinic patients, former patients, referrals from other physicians, and subjects that read about the Autonomic Dysfunction Center on the Vanderbilt website.