Learn more about Neuarally Mediatated Hypotension

Possible Causes: Neurally Mediated Hypotension 

Rowe and coworkers conducted studies to determine whether disturbances in the autonomic regulation of blood pressure and pulse (neurally mediated hypotension, or NMH) were common in CFS patients. The investigators were alerted to this possibility when they noticed an overlap between their patients with CFS and those who had NMH.

NMH can be induced by using tilt table testing, which involves laying the patient horizontally on a table and then tilting the table upright to 70 degrees for 45 minutes while monitoring blood pressure and heart rate.

Persons with NMH will develop lowered blood pressure under these conditions, as well as other characteristic symptoms, such as lightheadedness, visual dimming, or a slow response to verbal stimuli.

Many CFS patients experience lightheadedness or worsened fatigue when they stand for prolonged periods or when in warm places, such as in a hot shower. These conditions are also known to trigger NMH.

One study observed that 96% of adults with a clinical diagnosis of CFS developed hypotension during tilt table testing, compared with 29% of healthy controls. Tilt table testing also provoked characteristic CFS symptoms in the patients.

A study (not placebo-controlled) was conducted to determine whether medications effective for the treatment of NMH would benefit CFS patients. A subset of CFS patients reported a striking improvement in symptoms, but not all patients improved.

A placebo-controlled trial of NMH medications for CFS patients is now in progress.