Orthostatic hypotension (OH), also called postural hypotension, is a condition characterized by a significant drop in blood pressure upon standing. It results from impaired autonomic regulation and is particularly prevalent in neurodegenerative diseases, especially synucleinopathies like Parkinson's disease, multiple system atrophy, and Lewy body dementia.
- Baroreceptor activation upon standing
- Sympathetic nervous system activation
- Vasoconstriction via α-adrenergic receptors
- Heart rate increase
- Fluid retention mechanisms
- Impaired baroreflex function
- Reduced sympathetic outflow
- Venous pooling
- Inadequate vasoconstriction
- Neurotransmitter deficiency
- Lewy body pathology affecting autonomic centers
- Noradrenergic neuron loss
- Cardiac sympathetic denervation
- Central vs. peripheral mechanisms
- SBP drop ≥20 mm Hg OR
- DBP drop ≥10 mm Hg
- Within 3 minutes of standing
- Most common in autonomic failure
- Symptoms after 3-10 minutes
- Often more subtle
- May progress to classic OH
- Brief BP drop immediately upon standing
- Rapid recovery
- Often with vagal symptoms
- Present in 30-50% of PD patients
- Often early symptom
- Indicates more severe disease
- Associated with cognitive decline
- Cardiac sympathetic denervation
- More severe than in PD
- Earlier onset
- Neuropathic vs. central causes
- Poor treatment response
- Prognostic implications
¶ Lewy Body Dementia
- Common autonomic symptom
- Fluctuating cognition link
- Sleep behavior disorder association
- Treatment challenges
- Isolated autonomic dysfunction
- No parkinsonism or dementia
- Lewy body pathology
- Variable progression
- Metabolic cause of OH
- Small fiber involvement
- Treatment considerations
¶ Symptoms Upon Standing
- Lightheadedness
- Dizziness
- Weakness
- Fatigue
- Blurred vision
- Syncope (fainting)
- Exercise intolerance
- Neck pain (coat-hanger pain)
- Chest discomfort
- Headache
- Supine hypertension
- Nocturnal diuresis
- Heat intolerance
- Gastroparesis
¶ Active Standing Test
- Monitor BP supine, sitting, standing
- 3-minute observation
- Repeat after 1 minute
- Confirm diagnosis
- More controlled environment
- Reproducible results
- For atypical cases
- Differentiates subtypes
- Heart rate variability
- Valsalva maneuver
- Sudomotor function
- Thermoregulatory sweat test
- 24-hour Ambulatory BP
- Plasma catecholamines
- Autoantibody screening
- Diabetes workup
- Increased salt intake
- Fluid hydration (2-3 L/day)
- Compression stockings
- Head-of-bed elevation
- Avoid standing quickly
- Small frequent meals
- Exercise program
First-line:
- Midodrine (α1-agonist)
- Droxidopa (norepinephrine prodrug)
Second-line:
- Fludrocortisone (mineralocorticoid)
- Pyridostigmine (acetylcholinesterase)
- Atomoxetine (norepinephrine reuptake)
For Supine Hypertension:
- bedtime dosing
- shorter-acting agents
- nitrate supplements
- Nucleus tractus solitarius
- Dorsal motor nucleus of vagus
- Ventrolateral medulla
- Intermediolateral cell column
- Sympathetic preganglionic neurons
- Postganglionic sympathetic neurons
- Cardiac autonomic nerves
- Worsens over time
- Falls risk increases
- Quality of life impact
- Mortality association
- Severity at diagnosis
- Cardiac denervation
- Treatment response
- Associated diseases
This section highlights recent publications relevant to this disease.