Nejm 2008;358:615

Cause:

Primary degeneration of autonomic system, alone in Bradbury-Eggleston syndrome (BES), or combined w multisystem atrophy in Parkinson's disease (Ann IM 2000;133:382), olivopontocerebellar atrophy (prominent parkinsonian si), striatonigral degeneration (prominent cerebellar si's), Shy-Drager syndrome (SDS) (acquired), and Riley-Day syndrome (RDS) (congenital)

Secondary causes: CNS injury from spinal cord injury, esp above T₆, amyloid neuropathy, Guillain-Barré syndrome, diabetic neuropathy, cancer, HIV infection, porphyria, pernicious anemia, tabes dorsalis from syphilis, drug toxicity like alcoholic neuropathy

Pathophys:RDS from decreased dopamine norepinephrine conversion; BES and SDS from autoimmune antibodies to ganglionic Ach receptors (Nejm 2000;343:847) causing multineurosystem degeneration; diminished or no sympathetic CNS stimulation on standing

RDS in Eastern European Jews disappearing w prenatal screening (Neja 2009;361:1622)

Sx:

Postural hypotensive sx; heat intolerance; constipation (occasional diarrhea), dysphagia; nocturia, frequency, urgency, incontinence, urinary retention; erectile and ejaculatory failure; stridor, apnea; parkinsonism, ataxias

RDS: absent taste; intermittent skin blotching

SDS: a mix of autonomic failure, Parkinson's-type sx, and sometimes cerebellar sx

Si:

Postural hypotension; anhidrosis; anisocoria, Horner's syndrome; stridor, apnea; parkinsonism, cerebellar si's

RDS: loss of anterior tongue papillae; poor coordination; absent deep tendon reflexes; paroxysmal hypertension; defective temperature control and sweating; absent corneal reflexes

SDS: dementia, tremor

Autonomic dysreflexia = hypertensive crisis precipitated in quadriplegics by distended viscus (NE Rehab Hosp lecture 10/89)

r/o vasovagal syncope; carotid hypersensitivity; postural tachycardia syndrome (Nejm 2000;343:1008), incr pulse w/o decr BP in young women w partial sympathetic denervation of legs

Lab:

In RDS and SDS, methacholine sc causes eye tearing, transiently improved taste; in eye, i gtt methacholine causes potentiated miosis (denervation supersensitivity). Histamine intradermally causes no flare

Noninv:Measure with expiratory–inspiratory respiratory variation in sinus rates, if <10, suspect neuropathy present (BMJ 1982;285:559)

Rx:

of postural hypotension: avoid diuretics, vasodilators and tricyclics, increase salt intake and maybe rx of syst HT in elderly using low doses and increasing slowly (Lipsitz HMS 3/06); or try

• Dihydroergotamine 6.5-13 µgm/kg sc in am (Ann IM 1986;105:168), w
• Caffeine 250 mg po half-hour ac (Ann IM 1986;105:168; Nejm 1985;313:549)
• Fludrocortisone (Florinef) 0.1+ mg po qd (Nejm 1989;321:952)
• ß-Blockers
• Anticholinergics like disopyramide (Norpace) (Jama 1995;274:961)
• Midodrine 10 mg po tid (an agonist) (Med Let 1997;39:59; Jama 1997;277:1046)
• Ibuprofen (Motrin) ir indomethacin (Indocin) (Sci Am Text Med, 1986);

of SDS: L-dopa + above

If anemic (hct <40%), old or young, rx w erythropoietin (Ann IM 1994;121:181; Nejm 1993;329:611)