1. 3/98medslides.com1 Orthostatic Hypotension: causes, mechanisms, and influencing factors Christopher J Mathias, DPhil, FRCP Neurology 1995; 45:S6-S11

2. 3/98medslides.com2 Control of Blood Pressure autonomic nervous system heart’s resistance and capacitance intravascular volume hormones –renin-angiotensin-aldosterone system –aldosterone –local endothelin or nitric acid Neurology 1995; 45:S6-S11

3. 3/98medslides.com3 Orthostatic hypotension consensus definition (1) reduction of –systolic BP of at least 20 mm Hg, or –diastolic BP of at least 10 mm Hg within 3 minutes of standing (some may take more than 10 minutes) similar drop in blood pressure within 3 minutes in a head-up tilt table test at an angle of at least 60 degrees 1. Neurology 1996; 46:1470

4. 3/98medslides.com4 Orthostatic hypotension “when associated with relevant symptoms indicating impaired perfusion, a smaller drop in blood pressure may be equally important, especially for further investigation.” Neurology 1995; 45:S6-S11

5. 3/98medslides.com5 Orthostatic hypotension symptoms symptoms develop on assuming the erect posture –lightheadedness, dizziness, blurred vision, weakness, fatigue, cognitive impairment, nausea, palpitations, tremulousness, headache, neck ache some patients may be asymptomatic Neurology 1996; 46:1470

6. 3/98medslides.com6 Autonomic Nervous System Neurogenic causes of orthostatic hypotension Primary autonomic failure Secondary autonomic failure Neurology 1995; 45:S6-S11

7. 3/98medslides.com7 Primary autonomic failure chronic –pure autonomic failure –Shy-Drager syndrome with parkinsonian features with cerebellar and pyramidal features with multiple system atrophy (combination) acute or subacute dysautonomias Neurology 1995; 45:S6-S11

8. 3/98medslides.com8 Secondary autonomic failure central spinal peripheral miscellaneous drugs neurally mediated syncope Neurology 1995; 45:S6-S11

9. 3/98medslides.com9 Secondary autonomic failure 1. central brain tumors, especially of the 3rd ventricle or posterior fossa multiple sclerosis syringobulbia age-related Neurology 1995; 45:S6-S11

10. 3/98medslides.com10 Secondary autonomic failure 2. spinal spinal transverse myelitis transverse myelitis syringomyelia spinal tumor Neurology 1995; 45:S6-S11

11. 3/98medslides.com11 Secondary autonomic failure 3. peripheral afferent –Guillain-Barre syndrome, Tabes dorsalis, Holmes-Adie syndrome efferent –diabetes mellitus, amyloidsis, surgery, dopamine-b-hydroxylase deficiency afferent / efferent –familial dysautonomia (Riley-Day synd) Neurology 1995; 45:S6-S11

12. 3/98medslides.com12 Secondary autonomic failure 4. miscellaneous autoimmune and collagen disorders renal failure neoplasia human immunodeficiency virus infection Neurology 1995; 45:S6-S11

13. 3/98medslides.com13 Secondary autonomic failure 5. drugs centrally acting –clonidine, methyldopa, reserpine, barbiturates, anesthetics peripherally acting –guanethidine, bethanadine –phenoxybenzamine, prazosin –propranolol, timolol Neurology 1995; 45:S6-S11

14. 3/98medslides.com14 Secondary autonomic failure 6. neurally mediated syncope vasovagal syncope carotid sinus hypersensitivity micturition syncope glossopharyngeal neuralgia and syncope Neurology 1995; 45:S6-S11

15. 3/98medslides.com15 Neurogenic orthostatic hypotension pathophysiology major abnormality is the lack of neurally mediated vasoconstriction in large vascular beds (skeletal muscle and the splanchnic bed) gravitational pooling in the periphery with lack of compensatory change Neurology 1995; 45:S6-S11

16. 3/98medslides.com16 Plasma norepinephrine level measure of sympathetic activity in neurogenic OH, the sympathetic nervous system is not activated, the rise in NE level is minimal or absent despite a marked fall in BP basal NE level cannot determine the site of lesion Neurology 1995; 45:S6-S11

17. 3/98medslides.com17 Rise in plasma norepinephrine after 10 min Head-up tilt to 45 0 Noradrenaline (pg/mL) Multiple system atrophy Pure autonomic failure Dopamine ß-OH deficiency

18. 3/98medslides.com18 Nonneurogenic causes of hypotension cardiac impairment myocardialimpaired ventricular filling impaired outputcardiac arrhythmia vasodilatation low intravascular volume blood / plasma lossfluid / electrolytes miscellaneous Neurology 1995; 45:S6-S11

19. 3/98medslides.com19 Nonneurogenic Hypotension 1. cardiac impairment myocardial myocarditis, myocardial infarction impaired ventricular filling atrial myxoma, constrictive pericarditis impaired output aortic stenosis, hypertrophic cardiomyopathy cardiac arrhythmia bradycardia, tachydysrhythmias Neurology 1995; 45:S6-S11

20. 3/98medslides.com20 Nonneurogenic Hypotension 2. vasodilatation drugs-nitrates alcohol heat, pyrexia hyperbradykinism systemic mastocytosis extensive varicose veins Neurology 1995; 45:S6-S11

21. 3/98medslides.com21 Nonneurogenic Hypotension 3. low intravascular volume Blood / plasma loss hemorrhage, burns, hemodialysis Fluid / electrolyte inadequate intake (anorexia, vomiting) diarrhea (including ileostomy) renal/endocrine (salt losing nephropathy, Addison’s, diabetes insipidus, diuretics Neurology 1995; 45:S6-S11

22. 3/98medslides.com22 Nonneurogenic Hypotension 3. miscellaneous Sepsis Endotoxic shock Neurology 1995; 45:S6-S11

23. 3/98medslides.com23 Factors influencing postural hypotension speed of positional change prolonged recumbency time of day (morning on rising) warm environment (hot weather, central heating, hot bath) Neurology 1995; 45:S6-S11

24. 3/98medslides.com24 Factors influencing postural hypotension food and alcohol (1) physical exertion (2) (bending forward, abdominal compression, leg crossing, squatting) increased intrathoracic pressure (micturition, cough, defication) 1. Mathias CJ, et al. 1992; Autonomic Failure 2. Smith GDP, et al. 1993; BHJ 1993; 69:359-361