Circulatory autonomic failure 50 years after acute poliomyelitis

Baroreflex-sympathoneural without baroreflex-cardiovagal failure in neurogenic orthostatic hypotension

We describe a patient with neurogenic orthostatic hypotension (nOH) after brainstem neurosurgery in whom baroreflex-cardiovagal function was normal despite baroreflex-sympathoneural failure. We also cite other conditions entailing differential alterations in the two efferent limbs of the baroreflex. Any condition involving nOH from selective loss of sympathetic noradrenergic innervation, interference with sympathetic pre-ganglionic transmission in the thoracolumbar spinal cord, sympathectomies, or attenuated intra-neuronal synthesis, storage, or release of norepinephrine would be expected to manifest with selective baroreflex-sympathoneural dysfunction. We advise caution in relying on indices of baroreflex-cardiovagal function for diagnosing nOH, since normal values for these indices do not exclude nOH.

Fludrocortisone and sleeping in the head-up position limit the postural decrease in cardiac output in autonomic failure

Treatment with head-up tilt sleeping and low-dose fludrocortisone effectively minimizes orthostatic symptoms and increases orthostatic blood pressure in patients with neurogenic orthostatic hypotension. The aim of the present study was to examine whether the improvement in orthostatic blood pressure during combined treatment with low-dose fludrocortisone and nocturnal head-up tilt in patients with neurogenic orthostatic hypotension can be attributed to expansion of plasma volume or to increased total peripheral resistance. The effects of a 3-week treatment with fludrocortisone and nocturnal head-up tilting on the postural changes in arterial pressure, heart rate, and cardiac output (pulse contour) were evaluated in eight consecutive patients with orthostatic hypotension. The period during which the patients were able to remain in the standing position without orthostatic complaints increased minimally from 3 to 10 minutes. The decrease in arterial pressure after 1 minute of standing--(means with standard deviations in parentheses) systolic, 49 (20) mm Hg; diastolic, 18 (11) mm Hg--before treatment was produced by a greater than normal decrease in cardiac output: 37% (10%) in patients with neurogenic orthostatic hypotension versus -14% (8%) in control subjects. Treatment increased upright arterial pressure from 83 (19) mm Hg systolic and 55 (13) mm Hg diastolic to 114 (22) mm Hg systolic and 60 (16) mm Hg diastolic by limiting the decrease in cardiac output. Body weight increased but hematocrit did not change. Leg pressure-volume relationship decreased in the two patients studied. The responses of plasma renin activity and aldosterone to orthostatic stress prior to treatment were subnormal and became even lower after treatment. The improvement in upright blood pressure in orthostatic hypotension during treatment with fludrocortisone and nocturnal head-up sleeping is the result of a reduction in the orthostatic decrease in cardiac output. Preliminary data suggest that the expanded body fluid volume is allocated to the perivascular space rather than to the intravascular space.

Patients' choice of portable folding chairs to reduce symptoms of orthostatic hypotension

Patients with neurogenic orthostatic hypotension may use portable folding chairs to prevent or reduce symptoms of low blood pressure. However, a concomitant movement disorder may limit the use of these chairs in daily living. In this prospective study, 13 patients with orthostatic hypotension, balance disturbance associated with motor disability, or both examined three commercially available portable folding chairs. A questionnaire was used to document the characteristics in chair design that were relevant for satisfactory use to these patients. Armrests, seat width, and an adjustable sitting height were found to be important features of a portable folding chair. One chair was selected by 11 of 13 patients to fit most needs.

The post-polio syndrome as an evolved clinical entity. Definition and clinical description

Post-polio syndrome (PPS) refers to the new neuromuscular symptoms that occur at least 15 years after stability in patients with prior acute paralytic polio-myelitis. They include: (1) new muscle weakness and atrophy in the limbs, the bulbar or the respiratory muscles [post-poliomyelitis muscular atrophy (PPMA)] and (2) excessive muscle fatigue and diminished physical endurance. PPS is a clinical diagnosis that requires exclusion of all other medical, neurological, orthopedic or psychiatric diseases that could explain the cause of the new symptoms. Routine electromyography is useful to confirm chronic and ongoing denervation and exclude neuropathies. Muscle biopsy, single fiber electromyography (EMG), macro-EMG, serum antibody titers to polio virus, and spinal fluid studies are very useful research tools but they are rarely needed to establish the clinical diagnosis. PPS is a slowly progressive phenomenon with periods of stability that vary from 3 to 10 years. Current evidence indicates that PPS is the evolution of a subclinically ongoing motor neuron dysfunction that begins after the time of the acute polio. It is clinically manifested as PPS when the well-compensated reinnervating process crosses a critical threshold beyond which the remaining motor neurons cannot maintain the innervation to all the muscle fibers within their motor unit territory.

Treatment of orthostatic hypotension with sleeping in the head-up tilt position, alone and in combination with fludrocortisone

We studied the effect of sleeping in the head-up tilt (HUT) position, alone and in combination with fludrocortisone, on orthostatic tolerance and blood pressure (BP) in six patients with hypoadrenergic orthostatic hypotension. A high salt diet of 150-200 mmol Na+ d-1 was also administered. Combined treatment reduced orthostatic dizziness in all patients (P less than 0.001), and increased the maximal standing period to at least 10 min. HUT alone (n = 4) reduced the BP decrease after 1 min of standing from -64/-42/-25 +/- 29/21/17 mmHg to -53/-37/-23 +/- 31/24/20 mmHg (P less than 0.01 for systolic BP). Addition of fludrocortisone to HUT (HUT/fludro) (n = 5) further reduced the BP decrease after 1 min of standing from -63/-40/-24 +/- 20/12/11 mmHg to -21/-19/-8 +/- 12/10/5 mmHg (P less than 0.05 for systolic, mean and diastolic BP, respectively). BP at maximal standing time increased from 58/47/42 +/- 9/8/7 mmHg initially to 95/69/57 +/- 27/22/20 mmHg during combined treatment (P less than 0.05 for systolic and mean BP), and remained unchanged during the 14-month (range 8-70 month) follow-up period. Nocturnal sodium excretion decreased from 8.0 +/- 2.3 mmol h-1 to 5.9 +/- 1.9 mmol h-1 with combined treatment; body weight increased by 1.6 kg on average (range 0.5-2.4 kg) (P less than 0.01). We conclude that the combination of HUT and fludrocortisone effectively minimizes orthostatic symptoms and increases orthostatic BP in patients with hypo-adrenergic orthostatic hypotension.