Synergistic effect of norepinephrine transporter blockade and α-2 antagonism on blood pressure in autonomic failure

Patients with autonomic failure have disabling orthostatic hypotension because of impaired sympathetic activity. Norepinephrine transporter blockade with atomoxetine raises blood pressure in autonomic failure by increasing synaptic norepinephrine concentrations in postganglionic sympathetic neurons. This effect requires tonic release of norepinephrine, which is decreased in patients with low sympathetic tone. We hypothesized that increasing residual sympathetic outflow with the α-2 antagonist yohimbine would potentiate the pressor effect of norepinephrine transporter blockade with atomoxetine and improve orthostatic tolerance in peripheral autonomic failure. Seventeen patients received a single oral dose of either placebo, yohimbine 5.4 mg or atomoxetine 18.0 mg, and the combination yohimbine and atomoxetine in a single blind, crossover study. Blood pressure was assessed while patients were seated and standing for ≤10 minutes before and 1 hour postdrug. Neither yohimbine nor atomoxetine significantly increased seated systolic blood pressure or orthostatic tolerance compared with placebo. The combination, however, significantly increased seated systolic blood pressure and orthostatic tolerance (P<0.001 and P=0.016, respectively) in a synergistic manner. The maximal increase in seated systolic blood pressure seen with the combination was 31±33 mm Hg at 60 minutes postdrug. Only the combination showed a significant improvement in orthostatic symptoms. In conclusion, the combination of yohimbine and atomoxetine had a synergistic effect on blood pressure and orthostatic tolerance in peripheral autonomic failure, which may be explained by an increased release of norepinephrine in peripheral sympathetic neurons by α-2 antagonism combined with a reduced norepinephrine clearance by norepinephrine transporter blockade. Safety studies are required to address the clinical usefulness of this pharmacological approach.

[General anesthesia in a patient with idiopathic orthostatic hypotension]

Idiopathic orthostatic hypotension (formerly known as Shy-Drager syndrome) is a multiple system atrophy, which is characterized by autonomic dysregulation. Providing perioperative hemodynamic stability during narcosis is therefore a particular challenge. The effects of general anesthesia on systemic vascular resistance and cardiac output in a patient with idiopathic orthostatic hypotension undergoing retropubic prostatectomy will be reported. In the case presented perioperative hemodynamic stability was achieved by aggressive volume therapy guided by global end-diastolic volume measurement and low-dose catecholamine therapy.

Pyridostigmine Treatment Trial in Neurogenic Orthostatic Hypotension

BACKGROUND

Midodrine hydrochloride is the only drug demonstrated in a placebo-controlled treatment trial to improve orthostatic hypotension (OH) but it significantly worsens supine hypertension. By enhancing ganglionic transmission, pyridostigmine bromide can potentially ameliorate OH without worsening supine hypertension.

OBJECTIVE

To evaluate the efficacy of a single 60-mg dose of pyridostigmine bromide, alone or in combination with a subthreshold (2.5 mg) or suprathreshold (5 mg) dose of midodrine hydrochloride, compared with placebo.

DESIGN

We report a double-blind, randomized, 4-way cross-over study of pyridostigmine in the treatment of neurogenic OH. A total of 58 patients with neurogenic OH were enrolled. After 1 day of baseline measurements, patients were given 4 treatments (3 active treatments [60 mg of pyridostigmine bromide; 60 mg of pyridostigmine bromide and 2.5 mg of midodrine hydrochloride; 60 mg of pyridostigmine bromide and 5 mg of midodrine hydrochloride] and a placebo) in random order on successive days. Blood pressure (BP) and heart rate were measured, both supine and standing, immediately before treatment and hourly for 6 hours after the treatment was given.

RESULTS

No significant differences were seen in the supine BP, either systolic (P = .36) or diastolic (P = .85). In contrast, the primary end point of the fall in standing diastolic BP was significantly reduced (P = .02) with treatment. Pairwise comparison showed significant reduction by pyridostigmine alone (BP fall of 27.6 mm Hg vs 34.0 mm Hg with placebo; P = .04) and pyridostigmine and 5 mg of midodrine hydrochloride (BP fall of 27.2 mm Hg vs 34.0 mm Hg with placebo; P = .002). Standing BP improvement significantly regressed with improvement in OH symptoms.

CONCLUSIONS

Pyridostigmine significantly improves standing BP in patients with OH without worsening supine hypertension. The greatest effect is on diastolic BP, suggesting that the improvement is due to increased total peripheral resistance.

Fludrocortisone in patients with familial dysautonomia--assessing effect on clinical parameters and gene expression

The common familial dysautonomia (FD) mutation causes a splicing defect that leads to production of both wild-type (WT) and mutant (MU) IKBKAP mRNA. Because drugs may alter splicing, seven drugs, fludrocortisone, midodrine, diazepam, albuterol, clonidine, caffeine, and dopamine were screened. Since only fludrocortisone negatively altered gene expression, we assessed fludrocortisone's efficacy in treating postural hypotension, and its effect on survival and secondary long-term FD problems. For 341 FD patients we obtained demographic data and clinical information from the last Center evaluation (most current or prior to death) including mean blood pressures (supine, 1 min erect and 5 min erect) and history regarding syncope and presyncope symptoms. For 175 fludrocortisone-treated patients, data from the evaluation prior to start of fludrocortisone and from the last Center evaluation were compared. The fludrocortisone-treated patient cohort was compared to the nontreated patient cohort with respect to overall survival and event-free survival for crisis frequency, worsening gait, frequent fractures, spine curvature, renal insufficiency, and pacemaker insertion. Overall survivals of patients on fludrocortisone alone, on fludrocortisone and midodrine, and on neither drug were compared. Cumulative survival was significantly higher in fludrocortisone-treated patients than in non-treated patients during the first decade. In subsequent decades, the addition of midodrine improved cumulative survival. Fludrocortisone significantly increased mean blood pressures and decreased dizziness and leg cramping, but not headaches or syncope. Fludrocortisone was associated with more long-term problems, which may reflect more symptomatic status associated with longer survival. Our data suggest that fludrocortisone has clinical efficacy despite negative in vitro observations on gene expression.

Drug treatment of orthostatic hypotension because of autonomic failure or neurocardiogenic syncope

Orthostatic hypotension either because of autonomic failure or neurocardiogenic syncope can be very incapacitating and should be treated accordingly. Drug therapy is frequently needed to alleviate orthostatic symptoms. The physiopathological basis of neurocardiogenic syncope and of autonomic failure is completely different and their treatment should be distinct. In the past 5 years, many randomized, placebo-controlled trials have shed light on the efficacy of specific pressor drugs. In patients with orthostatic hypotension because of autonomic failure, alpha-adrenoceptor agonists, and midodrine in particular, have been shown to increase standing blood pressure and decrease orthostatic symptoms. Other drugs such as octreotide, indomethacin or ergotamine have also been shown to elevate standing blood pressure and/or orthostatic tolerance. Fludrocortisone is a well known and frequently used pressor drug but randomized controlled studies are needed to measure its efficacy. In patients with orthostatic hypotension associated with neurocardiogenic syncope, clinical trials have demonstrated that beta-blockers, especially beta(1)-selective agents without intrinsic sympathomimetic activity such as atenolol, midodrine and paroxetine can decrease recurrence of syncope. Treatment algorithms, such as those presented in this review, should always be interpreted in the light of individual patient characteristics. Many of the drugs used for orthostatic hypotension have multiple indications and contraindications that should influence therapeutic decisions. Little is known about the effectiveness and tolerability of specific combinations of pressor drugs. Consequently, sound clinical judgment and close follow-up of patients should always guide combination therapy.

[Blood pressure and heart rate regulation in diabetics]

Cardiac autonomic neuropathy (CAN) is frequent in subclinical stages. Its prognostic value has been demonstrated. Cardiac autonomic neuropathy induces different functional cardiac changes, especially a reduction in left ventricular contractility and changes in ventricular repolarisation. It is also associated with changes in the daily variations in blood pressure. The association of CAN and silent myocardial ischaemia significantly worsens the prognosis. The investigation of CAN in the greatest number of diabetic patients is therefore justified. The study of heart rate variations during deep respiration, active orthostatism or Valsalva manoeuvre, is still the reference. This method is simple, reproducible and may be carried out in the clinical setting in 10 to 15 minutes. The results must be strictly interpreted with rigour with respect to age. Orthostatic hypotension is a late sign of sympathetic nervous system disease. Spectral analysis of blood pressure variations on orthostatism or the study of cutaneous blood flow during activating the sympathetic system tests of greater sensitivity, should be developed. The demonstration of subclinical CAN should lead to the careful use of drugs which may induce orthostatic hypotension and certain antiarrhythmics, to search for disorders of ventricular repolarisation and for silent myocardial ischaemia in diabetics with several risk factors.

Ambulatory infusion of noradrenaline for long-term treatment of Shy-Drager syndrome

A 70-year-old female patient with advanced Shy-Drager syndrome exhibited severe orthostatic hypotension, low serum catecholamine levels, and autonomic dysfunction. She was bedridden despite oral medication with fludrocortisone, etilefrin, dihydroergotamine, L-dopa, yohimbine, and amezinium methyl sulfate. Only intravenous application of noradrenaline (30 ng/kg/min) provided complete mobilization. After implantation of a port-a-cath system, intravenous noradrenaline treatment could be continued on an outpatient basis. Over the following 5 years, the patient was throughout sufficiently mobile and did not show any significant side effects of this treatment. However, during the 5th year she suffered from nonhemorrhagic brain stem infarction due to cerebral hypoperfusion after orthostatic stress in the absence of noradrenaline infusion. We conclude that ambulatory noradrenaline infusion is a new valuable tool for long-term treatment of advanced Shy-Drager syndrome.

[Shy-Drager syndrome: a rare cause of orthostatic hypotension]

HISTORY AND ADMISSION FINDINGS

A 71-year-old man was admitted because of treatment-resistant orthostatic hypotension of unknown aetiology. When aged 64 years he developed some impotence and later urinary incontinence and urinary frequency. At 68 years he noted vertigo on physical activity, and a year later he had signs of reversible cerebral ischaemia. At this point the Schellong test demonstrated vasovagal circulatory dysfunction. After his 70th birthday the unsteadiness on walking and standing got worse and he had recurrent syncopes. He was in a wheel-chair when hospitalized and even the unsteady walk he could maintain for only a few seconds.

INVESTIGATIONS

Plasma and urinary concentrations of catecholamines were at the lower limit of normal but failed to increase during orthostasis. Hormonal, cardiological and infectious causes of the orthostatic hypotension were excluded. Orthostatic tests after Schellong and with the tilting table showed orthostatic hypotension without increased sympathetic activity but hypertensive blood pressure levels during the recumbent period. Intravenous infusion of norepinephrine produced an excess rise in blood pressure (raised norepinephrine sensitivity). The recurrent urinary infection was shown to be due to a hypotonic bladder detrusor muscle. Neurological examination revealed cerebellar dysfunction, signs of pyramidal tract abnormality and sensory polyneuropathy. A Shy-Drager syndrome was diagnosed on the basis of the history, absent blood pressure rise and lack of catecholamine release during orthostasis with increased epinephrine sensitivity and characteristic neurological signs.

TREATMENT AND COURSE

Physiotherapy and elastic stockings with administration of mineralocorticoids as well as of one direct (norfenefrine) and one indirect (amezinium) sympathomimetic drug failed to improve adequately the abnormal orthostatic response. But on additional administration of an alpha 2-receptor antagonist (yohimbine) the patient was able to stand and walk for a few minutes, but the urinary incontinence and the other neurological signs remained treatment-resistant.

CONCLUSION

If orthostatic hypotension occurs together with neurological symptoms, a Shy-Drager syndrome should be taken into account.

[A case of impending neuroleptic malignant syndrome associated with Shy-Drager syndrome]

We report a 55-year-old man with impending neuroleptic malignant syndrome who showed a remarkable dysautonomia such as dysuria and was treated with L-dopa under the diagnosis of Shy-Drager syndrome. The patient demonstrated fever, leukocytosis and elevated serum creatine kinase by a decrease in L-dopa dose. Probably, he developed impending neuroleptic malignant syndrome, induced by urinary tract infection as well as decrease in L-dopa dose. Since Shy-Drager syndrome is often treated with antiparkinsonian drugs, neuroleptic malignant syndrome can possibly develop after the change in dosage of catecholaminergic drugs. The imbalance of neurotransmitters and receptors in the central autonomic nervous system may participate in the development of neuroleptic malignant syndrome. Accordingly, Shy-Drager syndrome can easily be associated with neuroleptic malignant syndrome because of its severe disturbance in the autonomic nervous system. However, autonomic nervous dysfunction, a major sign of neuroleptic malignant syndrome, might be masked by symptoms of Shy-Drager syndrome. Therefore, diagnosis of neuroleptic malignant syndrome is often delayed. Careful observations of patients with Shy-Drager syndrome related with an antiparkinsonian drug are necessary, especially when the dose of drugs is changed or the general condition deteriorates.

Recent advances in the treatment of orthostatic hypotension

Orthostatic hypotension is a fall in blood pressure on standing that causes symptoms of dizziness, visual changes, and discomfort in the head and neck. The goal of treatment is the improvement of the patient's functional capacity, rather than a target blood pressure. For treatment to be successful, it must be individualized. Non-pharmalogic interventions include carefully managed exercise, scheduled activities, and monitoring of the environmental temperature. Agents such as fludrocortisone, midodrine, and epoetin alfa offer successful pharmacologic interventions. Although these measures ease the symptoms of orthostatic hypotension, current approaches neither reverse nor stabilize the disease process in autonomic disorders.

[Orthostatic hypotension]

We report about a 67-year-old woman presenting with progressive orthostatic vertigo, urinary incontinence and clinical signs of Parkinson's disease. The Schellong test revealed deficient sympathetic orthostatic pressure response without an increase of plasma norepinephrine; therefore, a Shy-Drager syndrome was diagnosed. Because of inefficiency of the general measures (compressive pantyhose), the sympathomimetic agonists, and the centrally active alpha-2-antagonists, norepinephrine was administered via a miniature dosing pump. By this therapeutic regimen a marked improvement of orthostatic hypotension was achieved.

[Shy-Drager syndrome]

An 81-year-old man with a history of chronic pulmonary disease due to heavy smoking and ischemic heart disease had been suffering for the past few years from chronic constipation and urinary incontinence and was receiving medication for cardiopulmonary symptoms and urinary incontinence. He was admitted for repeated falling for a few months prior to admission. When put in the supine position, his blood pressure fell. He had bilateral pulmonary rales, consistent with lung disease, eccentricity of the left pupil (after cataract surgery), constriction of the right pupil, and absence of the pupillary light reflex. There was generalized hyperreflexia and a bilateral Babinski sign. He had normocytic, normochromic anemia; B12, folic acid and ferritin were within normal ranges, ESR was rapid, there was hyperglobulinemia (IgA and IgG), urea nitrogen and creatinine were increased but returned to normal after rehydration. ECG and chest X-ray were consistent with his cardiopulmonary status. Bone-marrow biopsy showed hypocellularity. IVP and barium enema were normal. Echocardiography revealed a possible old posterior wall myocardial infarction. CT-scan showed moderate cerebral and cerebellar atrophy, calcifications in the carotid and vertebral arteries, and small infarcts in both hemispheres. At this point, after an extensive survey of the literature, the diagnosis of Shy-Drager syndrome was proposed and proved by monitoring ECG and serum levels of noradrenaline during postural changes. He was treated with Fluorinef and there were no more episodes of postural hypotension. Several weeks after discharge he reported that he was feeling well and had not fallen since discharge.

High beta-adrenoceptor density on peripheral blood mononuclear cells in progressive multiple sclerosis: a manifestation of autonomic dysfunction?

In multiple sclerosis (MS) up-regulation of beta-adrenoceptors on peripheral blood mononuclear cells (PBMCs) has been attributed to either autonomic dysfunction, inflammation or a combination of the two. We have compared secondary progressive MS patients with normal subjects (NS) and two models of autonomic dysfunction; pure autonomic failure (PAF) and multiple system atrophy (MSA, Shy-Drager syndrome). There was up-regulation of beta-adrenoceptors on PBMCs in MS and PAF patients but not in MSA patients. Only in PAF patients beta-adrenoceptor up-regulation was correlated with low plasma levels of noradrenaline (NA) and adrenaline (Ad). In addition to studies in the basal state, measurements also were made after the centrally acting sympatholytic agent clonidine. These were combined with haemodynamic and neurohormonal measurements. After clonidine, there was a fall in blood pressure in NS and MSA patients but not in MS and PAF patients; a rise in growth hormone (GH) in NS and PAF patients but not in MS and MSA patients; and an up-regulation in PBMCs beta-adrenoceptors in NS but not in MS, MSA and PAF patients. Up-regulation of beta-adrenoceptors on PBMCs in MS could be attributed to autonomic dysfunction but the disparity between MS and PAF patients when considering their plasma levels of NA and Ad argue against. Although the neurohormonal responses to clonidine and the physiological assessment of autonomic function in progressive MS patients, demonstrate central autonomic dysfunction resembling that of the MSA patients, the normal basal beta-adrenoceptor densities in the latter, suggests that the up-regulation of these receptors is independent of the central autonomic dysfunction in MS.

Cholinergic dysfunction in Shy-Drager syndrome: effect of the parasympathomimetic agent, bethanechol

To determine the frequency, severity and organ distribution of cholinergic dysfunction in the Shy-Drager syndrome, eleven patients were prospectively studied. In addition to documenting adrenergic insufficiency, a battery of twelve tests was employed to assess cholinergic function. Six tests demonstrated pupillary, lacrimal, salivary, urinary bladder, sexual and sudomotor dysfunction in the majority of patients. Cardiac vagal function as studied by the heart rate response to deep breathing, the Valsalva manoeuvre, cold face test, apnoeic facial immersion and atropine test was affected in all patients. Oesophageal motility was abnormal in six patients. Cholinergic dysfunction in patients with the Shy-Drager syndrome was widespread but of variable severity and distribution. Subcutaneous administration of the parasympathomimetic agent bethanechol demonstrated hyperresponsiveness of lacrimal, salivary, oesophageal, bowel, bladder and sudomotor functions. It is suggested that the Shy-Drager syndrome is primarily a preganglionic cholinergic disorder with transsynaptic degeneration accounting for the development of postganglionic cholinergic as well as adrenergic dysfunction.

Bilateral vocal cord paralysis with Shy-Drager syndrome

Shy-Drager syndrome consists of progressive autonomic nervous system failure with Parkinson's disease-like symptoms and orthostatic hypotension. It can also result in airway compromise from bilateral vocal cord paralysis. Fewer than 30 cases of severe bilateral vocal cord paresis or paralysis associated with the Shy-Drager syndrome have been reported in the English literature. We present a case of a 72-year-old man who had a 2-year history of orthostatic hypotension, neurogenic bladder, impotence, anhydrosis, and extremity weakness and paresthesias. Hoarseness and dyspnea with stridor developed as a result of bilateral vocal cord paralysis in the median position and required an emergency tracheotomy. This combination of symptoms resulted in the diagnosis of Shy-Drager syndrome. We present the case along with literature review of bilateral vocal cord paralysis with the Shy-Drager syndrome.

Beta-adrenoceptor expression on circulating mononuclear cells of idiopathic Parkinson's disease and autonomic failure patients before and after reduction of central sympathetic outflow by clonidine

There is a short-term up-regulation of beta-adrenoceptors on peripheral blood mononuclear cells (PBMC) after reduction of central sympathetic outflow by clonidine in normal individuals. We have studied beta-adrenoceptor number and affinity on PBMC in idiopathic Parkinson's disease (PD), pure autonomic failure (PAF), and multiple system atrophy (MSA; Shy-Drager syndrome) patients and age- and sex-matched normal controls (NC) before and after intravenous administration of clonidine, an alpha 2-adrenoceptor agonist which lowers blood pressure predominantly by reducing CNS sympathetic outflow. Basal beta-adrenoceptor density was high in PAF but within the normal range in PD and MSA patients. After clonidine there was a decrease in plasma levels of noradrenaline (NA) and adrenaline (Ad) in PD, MSA, and NC, and an increase in growth hormone (GH) in PD, PAF, and NC. NC. In PAF, NA and Ad remained unchanged. In MSA, there was no increase in GH levels. There was an up-regulation of beta-adrenoceptors on PBMC at 30 and 60 minutes after clonidine administration, which returned to baseline values after 2 hours, and the affinity of the receptors was decreased in NC and PD patients. Intracellular production of cAMP after isoproterenol stimulation demonstrated that the up-regulation was not functional. Up-regulation after clonidine did not occur in PAF and MSA patients. The observed correlation of plasma NA and sympathetic defect with basal and clonidine-induced up-regulation of beta-adrenoceptors on PBMC may provide insight into beta-adrenoceptor changes in other tissues and also help in differentiating subgroups of autonomic failure patients.

[Hyperthermia in a Shy-Drager syndrome patient--pathophysiological effects of body temperature and L-DOPS on orthostatic hypotension]

A 65-year-old man was admitted to our hospital because of syncope, hyperthermia and urinary disturbance. Neurological examination revealed cerebellar ataxia, muscular rigidity, hyperreflexia with Babinski sign in both sides, and various autonomic dysfunctions including anisocoria, orthostatic hypotension and neurogenic bladder. He was diagnosed as having Shy-Drager syndrome (SDS). Oral administration of L-threo-3,4-dihydroxyphenyl-serine (L-DOPS) (300 mg/day) was started for orthostatic hypotension. After discharge he suffered from pneumonia at his house, and he kept himself warm because of a chill. The patient then fell into hyperthermia (44.0 degrees C), resulting in unconsciousness and a state of shock. He was transferred to our hospital again and was treated by body cooling and drip infusion of dopamine after which he recovered completely within one day. Control of body temperature and blood pressure was examined by heat loading and head-up tilt after heat loading, with or without administration of L-DOPS. These examinations showed that his rectal body temperature rose easily during heat loading and that this phenomenon was enhanced by the administration of L-DOPS. Moreover as his body temperature became higher, he more easily developed syncope due to orthostatic hypotension. It is suggested that in SDS patients, L-DOPS facilitates orthostatic hypotension and syncope in high temperature conditions.

[Dysautonomia and multi-systemic atrophy of the nervous system (Shy-Drager's syndrome)]

The clinical expressions of primary autonomic nervous system failure are more or less numerous, orthostatic hypotension being only one of them. Clinical analysis reveals 3 categories of manifestations: pure progressive dysautonomia, dysautonomia associated with Parkinson's disease, and dysautonomia associated with multiple system atrophy of the nervous system also known as Shy-Drager syndrome. Neuropathological studies show that lesions of the efferent autonomic nervous system (tractus intermediolateralis, sympathetic ganglia) are frequently associated with lesions of the central nervous system the role of which in dysautonomia is still imperfectly known. Lesions of the central nervous system may present as genuine Parkinson's disease with Lew bodies or as multiple systemic atrophy with its two best individualized aspects: striatonigral atrophy and olivopontocerebellar atrophy. These various neurological aspects have their counterpart in biochemical abnormalities, prognosis and response to treatment.

Effect of xamoterol in Shy-Drager syndrome

BACKGROUND

Xamoterol, a cardioselective beta 1-adrenoceptor partial agonist, has been reported to be effective on postural hypotension. We investigated the effect of xamoterol in five patients with Shy-Drager syndrome (SDS) in relation to their prevailing sympathetic nerve activity and sensitivity of beta-adrenoceptors and the change in circadian variation of blood pressure.

METHODS AND RESULTS

Ambulatory blood pressure over 24 hours was monitored by noninvasive sphygmomanometer (model 5200, Spacelab). Plasma norepinephrine levels of SDS patients were significantly lower than that of normal subjects (n = 5) both at rest (54 +/- 15 versus 178 +/- 83 pg/ml) and after 10-minute standing (74 +/- 24 versus 318 +/- 143 pg/ml). Infusion of isoproterenol (0.02 micrograms/kg/min) produced a mild rise of systolic blood pressure and tachycardia in normal subjects but resulted in marked hypotension and tachycardia in SDS subjects. After xamoterol administration (200 mg b.i.d.), systolic blood pressure and heart rate were significantly increased in the averages during the day; however, increases were more pronounced at night. In two of the five patients, the improvement in dizziness was large enough to enable them to increase their daily activities.

CONCLUSIONS

Our observations suggest that 1) beta 1-selective, high intrinsic sympathomimetic activity of xamoterol increases blood pressure and heart rate in patients with SDS as a consequence of their prevailing beta 1-adrenoceptor hypersensitive state, and 2) blood pressure monitoring over 24 hours appears to have important advantages in evaluating the therapeutic effects on postural hypotension.

Shy-Drager syndrome. Effect of fludrocortisone and L-threo-3,4-dihydroxyphenylserine on the blood pressure and regional cerebral blood flow

In nine cases of Shy-Drager syndrome, the changes in blood pressure and cerebral blood flow on sitting up from a supine position were studied. The influence of fludrocortisone, a synthetic mineralocorticoid, and L-threo-3,4-dihydroxyphenylserine (DOPS), a precursor of norepinephrine, on these changes was examined. On sitting up, the regional cerebral blood flow (rCBF) measured by Xe133 inhalation showed a tendency to decrease. Fludrocortisone reduced the fall of the mean blood pressure significantly. DOPS reduced the fall of both the diastolic blood pressure and rCBF significantly.

Xamoterol in the treatment of orthostatic hypotension associated with multiple system atrophy (Shy-Drager syndrome)

The effect of xamoterol on the orthostatic hypotension associated with Shy-Drager syndrome was investigated in three patients. Intra-arterial blood pressure was measured during a control period and during treatment with xamoterol, both in a cardiovascular investigation laboratory and for 24 h of unrestricted activity using portable apparatus. Xamoterol lessened the total number of symptomatic episodes of orthostatic hypotension by 67 per cent. Average untreated 24-h intra-arterial blood pressure was 132/78 mmHg; during treatment with xamoterol it rose to 138/90 mmHg. However episodes of severe hypertension (defined as a systolic intra-arterial blood pressure above 200 mmHg) were more frequent with xamoterol. Although xamoterol attenuated orthostatic hypotension, careful monitoring of ambulatory blood pressure may be necessary, particularly at the start of treatment, because of the development of severe supine hypertension. Intravenous test doses of xamoterol did not predict either the attenuation of orthostatic hypotension or the development of supine hypertension in all patients.

The effect of propranolol on catecholamine clearance

Normal subjects given propranolol increased their plasma t1/2 for infused isoproterenol from 2.68 to 6.25 minutes. Propranolol increased plasma norepinephrine (NE) levels only slightly. Propranolol increased the t1/2 of isoproterenol but not that of NE in men with autonomic nervous system degeneration. This suggests that propranolol acts on nonneuronal uptake-2 processes, rather than on uptake-1 mechanisms. alpha-Blockers slow uptake-1 and beta-blockers slow uptake-2 processes. When 27 subjects exercised, those who attained the highest plasma levels of the alpha- and beta-receptor agonist NE also had the briefest apparent t1/2 for NE. Adrenergic receptor blocking drugs slow catecholamine clearance. NE may stimulate its own clearance.

Long-term experience with pergolide therapy of advanced parkinsonism

Nine patients with idiopathic Parkinson's disease were treated with pergolide to a daily maintenance dose of 2.2 +/- 0.9 mg (mean +/- SD) for 17.3 +/- 8.3 months. After 1 month, there was an average 68% increase in mobile on-time, but the improvement declined to 30% by 6 months, 23% by 1 year, and virtually disappeared by 18 months of therapy. Pergolide was discontinued in seven patients because of loss of efficacy (4 patients), confusion (1 patient), or myocardial infarction or ventricular ectopy (2 patients). Partial but temporary restoration of mobility was observed in seven patients who were switched to an alternate-day dosing schedule after 9.2 +/- 2.4 months. Two patients with advanced Shy-Drager syndrome were treated with pergolide without benefit.

Prostacyclin biosynthesis and platelet function in autonomic dysfunction

We measured urinary excretion of the principal metabolite of prostacyclin, PGI-M (2,3-dinor-6-keto-PGF1 alpha) in two patients with Shy-Drager syndrome and three with idiopathic orthostatic hypotension. All patients had a rise in blood pressure (30 +/- 6 mm Hg) after ingestion of 50 mg indomethacin. Urinary excretion of PGI-M was normal and fell 57 +/- 11% after administration of indomethacin. In two subjects, there was no evidence of any circulating inhibitor of platelet aggregation when hypotension was induced by upright posture or ingestion of a meal. Despite the efficacy of indomethacin, these patients with autonomic dysfunction did not show increased production of the vasodilator prostanoid prostacyclin.

Multiple system atrophy. Clinical aspects, pathophysiology, and treatment

Progressive autonomic failure is a clinical syndrome of autonomic dysfunction that may occur in isolation as in idiopathic orthostatic hypotension (IOH) or in association with a central neurologic disorder, multiple system atrophy (MSA). MSA and IOH can be distinguished on the basis of biochemical and pharmacologic tests. Plasma norepinephrine levels are low in IOH and normal in MSA; neither group increases the plasma norepinephrine level adequately in response to postural change. Both MSA and IOH manifest an exaggerated pressor response to administered norepinephrine. However, only patients with IOH have true adrenergic receptor supersensitivity. The autonomic dysfunction in IOH primarily involves the peripheral autonomic neurons whereas the defect in MSA is the failure to activate appropriately an intact distal sympathetic nervous system. Neuropathologic studies reveal a multisystem degeneration in MSA; the few postmortem examinations of the central nervous system in IOH reveal lesions confined to the intermediolateral columns of the spinal cord. Orthostatic hypotension may be treated with a number of medications although supine hypertension limits the usefulness of these drugs. Further development and testing of a sympathetic neural prosthesis may help to resolve this therapeutic dilemma. Only the parkinsonian features in MSA respond to treatment with anticholinergic drugs.

Effect of prenalterol on orthostatic hypotension in the Shy-Drager syndrome

Treatment of idiopathic orthostatic hypotension is often unsatisfactory. A patient with the Shy-Drager syndrome, in which the most important symptom is orthostatic hypotension, was treated with prenalterol, initially 30 mg six times daily. The dosage was reduced to 30 mg four times daily because of the development of complex ventricular premature beats. Orthostatic symptoms were reduced and standing blood pressure increased. Fludrocortisone 0.5 mg a day was added to treatment with further improvement. This clinical effect was maintained throughout 12 months of follow up, during which the treatment was continued unchanged. Prenalterol was effective in reducing orthostatic symptoms in this patient. Further studies in patients with a similar haemodynamic pattern are indicated.

Hemodynamics in Shy-Drager syndrome and treatment with indomethacin

Hemodynamic studies were performed in a case of Shy-Drager syndrome with severe orthostatic hypotension. Marked depression of blood pressure was recognized immediately after the tilt-up, wherein decrease in cardiac output was detected (65 leads to 35 ml; stroke volume) during measurements by echocardiography. In association with the depression of blood pressure and decrease in cardiac output, Doppler sonograms showed the overall blood flow reduction in the brain-supplying arteries, suggesting some breakdown of autoregulation of the cerebral blood flow. Medication with indomethacin obviously limited the depression of blood pressure during the standing exercise. The pressor mechanism of indomethacin might be regarded as a result of increased vasoconstrictivity by inhibiting the synthesis of prostaglandins.

Midodrine. A new agent in the management of idiopathic orthostatic hypotension and Shy-Drager syndrome

Five patients with idiopathic orthostatic hypotension, two of whom had central nervous system manifestations (Shy-Drager syndrome), were treated with midodrine, an investigational alpha-adrenergic agonist, in a dosage of 2.5 to 5 mg three times daily. Significant improvement was observed in the standing systolic and diastolic blood pressures at the end of 1 week of therapy in all patients and has been maintained for 10 to 15 months in all patients. No symptomatic side effects were noted. Supine systolic hypertension occurred in two patients and was treated with small doses of metoprolol.

The use of lisuride in the treatment of multiple system atrophy with autonomic failure (Shy-Drager syndrome)

In a controlled trial lisuride, an ergolene derivative with dopamine receptor agonist properties was given maximum tolerated doses (2.4 mg/day) to seven patients with multiple system atrophy with autonomic failure (Shy-Drager syndrome). Improvement in Parkinsonian features occurred in only one patient and another patient who had been deriving marked benefit from levodopa treatment before the study began failed to respond to large doses of lisuride. Psychiatric side effects (including nightmares, isolated visual hallucinations and toxic confusional states) were the dose-limiting factor in six patients. A modest reduction in orthostatic hypotension occurred in two patients, one of whom had experienced an aggravation of this disturbance on levodopa and bromocriptine. Destruction of post-synaptic dopamine receptors and damage to central noradrenergic systems may offer an explanation for the lack of therapeutic effect of lisuride.

Plasma catecholamines during activation of the sympathetic nervous system in a patient with Shy-Drager syndrome

Plasma catecholamines and circulation parameters were studied in a patient with a Shy-Drager syndrome. Basal values of free noradrenaline and dopamine were within the normal range, whereas the adrenaline level was decreased. The response of plasma catecholamines to different kinds of physical activity was pathological. The inability to maintain elevated catecholamine levels during prolonged activity corresponded to imparied circulatory regulation and may provide an additional tool for diagnosis and monitoring of the Shy-Drager syndrome.

Shy-Drager syndrome: diagnosis and treatment of cholinergic dysfunction

Two patients with Shy-Drager syndrome demonstrated unusually widespread and unequivocal cholinergic dysfunction as well as the usual evidence of adrenergic insufficiency. Progressive constipation preceded impotence, nocturia, hesitancy in micturition, anhidrosis, orthostatic hypotension, and xerostomia. Nonautonomic neurologic signs appeared several years later. Cholinergic dysfunction involved eyes, lacrimal glands, salivary glands, heart, gastrointestinal tract, urinary bladder, and sweat glands. Subcutaneous administration of bethanechol chloride--a muscarinic receptor agonist--improved tearing, salivation, sweating, and gastrointestinal and bladder functions. Daily administration of this drug resulted in symptomatic improvement of the autonomic functions, and relapse followed discontinuation of treatment.