Consensus statement on the definition of orthostatic hypotension, pure autonomic failure, and multiple system atrophy

Orthostatic hypotension (OH) is a reduction of systolic blood pressure of at least 20 mm Hg or diastolic blood pressure of at least 10 mm Hg within 3 minutes of standing. It is a physical sign and not a disease. An acceptable alternative to standing is the demonstration of a similar drop in blood pressure within 3 minutes, using a tilt table in the head-up position, at an angle of at least 60 degrees.

Confounding variables to be considered when reaching a diagnosis should include: food ingestion, time of day, state of hydration, ambient temperature, recent recumbency, postural deconditioning, hypertension, medications, gender, and age.

Orthostatic hypotension may be symptomatic or asymptomatic. Symptoms of OH are those that develop on assuming the erect posture or following head-up tilt and usually resolve on resuming the recumbent position. They may include lightheadedness, dizziness, blurred vision, weakness, fatigue, cognitive impairment, nausea, palpitations, tremulousness, headache, and neck ache. If the patient has symptoms suggestive of, but does not have documented, orthostatic hypotension, repeated measurements of blood pressure should be performed. Occasional patients may not manifest significant falls in blood pressure until they stand for at least 10 minutes.

Pure autonomic failure is an idiopathic sporadic disorder characterized by OH usually with evidence of more widespread autonomic failure. No other neurological features are present. Some patients with the manifestations of PAF may later prove to have other disorders such as multiple system atrophy. Reduced supine plasma norepinephrine levels are characteristic of PAF.

A minority of patients with Parkinson's disease as defined by United Kingdom Parkinson's Disease Brain Bank criteria ¹ may also develop autonomic failure, including OH. It is not known if these patients have a more serious prognosis than Parkinson's disease without autonomic failure.

MSA is a sporadic, progressive, adult onset disorder characterized by autonomic dysfunction, parkinsonism, and ataxia in any combination. The features of this disorder include:

Characteristically, these features cannot be explained by medications or other disorders. Parkinsonian and cerebellar features commonly occur in combination. However, certain features may predominate. When parkinsonian features predominate, the term striatonigral degeneration is often used. When cerebellar features predominate, sporadic olivopontocerebellar atrophy is often used. When autonomic failure predominates, the term Shy-Drager syndrome is often used. These manifestations may occur in various combinations and evolve with time.

Consensus Committee Participants include: Irwin J. Schatz, MD (Co-Chair), Department of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii, USA; Sir Roger Bannister (Co-Chair), Pembroke College, Oxford, UK, Roy L. Freeman, MD, Division of Neurology, Deaconess Hospital, Boston, Massachusetts, USA; Christopher G. Goetz, MD, Department of Neurology, Rush Medical College, Chicago, Illinois, USA, Joseph Jankovic, MD, Department of Neurology, Baylor College of Medicine, Houston, Texas, USA; Horacio C. Kaufmann, MD, Department of Neurology, Mount Sinai School of Medicine, New York, New York, USA William C. Koller, MD, Department of Neurology, University of Kansas, Kansas City, Kansas, USA; Phillip A. Low, MD, Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA; Christopher J. Mathias, MD, St. Mary's Hospital/Imperial College School of Medicine and the National Hospital/Institute of Neurology, Queen Square, London, UK, Ronald J. Polinsky, MD, Sandoz Research Institute, East Hanover, New Jersey, USA Niall P. Quinn, MD, Institute of Neurology, University Department of Clinical Neurology, The National Hospital, London, UK David Robertson, MD, Autonomic Dysfunction Center, Vanderbilt University, Nashville, Tennessee, USA, David H.P. Streeten, MD, Department of Medicine, Health Science Center, Syracuse, New York, USA.