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Background: Supine hypertension and post-prandial hypotension are associated with chronic autonomic failure, and may prove resistant to treatment. We determined if the hypotensive effects of food could be utilised to reduce supine hypertension in pure autonomic failure (PAF)., Methods: A subject with long-standing PAF, documented supine hypertension and post-prandial hypotension had a gastrostomy tube placed for dysphagia. We compared 24-hour ambulatory blood pressure recordings before and after nocturnal gastrostomy feeding., Results: Gastrostomy feeding was associated with resolution of supine hypertension and normalization of circadian BP rhythm., Conclusions: Gastrostomy feeding at night may help reduce supine hypertension in autonomic failure.

The spinal cord is essential for normal autonomic nervous system regulation of the cardiovascular system as the preganglionic neurons controlling the heart and blood vessels originate in the thoracolumbar spinal segments. The site and extent of a spinal cord injury determine the degree of autonomic involvement in cardiovascular dysfunction after the injury. After complete cervical cord lesions the entire sympathetic outflow is separated from cerebral control; this may cause orthostatic hypotension. Commonly after traumatic injuries to the spinal cord, one or more segments are totally destroyed. However, the distal portion of the spinal cord often retains function and activation of spinal cord reflexes working independently of the brain can result in paroxysmal hypertension. This chapter will focus on orthostatic hypotension and paroxysmal hypertension in cord-injured people with lesions affecting the cervical and upper thoracic spinal cord. Conditions promoting these abnormalities in blood pressure will be elaborated. Possible mechanisms for the hypo- and hypertension will be discussed, as will strategies for managing these problems.

On head down tilt to the supine horizontal position (tilt reversal) after head up tilt (HUT), patients with orthostatic hypotension may show an increase in blood pressure (BP) relative to baseline readings. We assessed this BP overshoot in 8 patients with pure autonomic failure (PAF, 64+/-13 years) and 8 patients with multiple system atrophy (MSA, 66+/-10 years). BP was intermittently measured during pre-tilt supine, HUT (60 degrees , 10 min), and post-tilt supine periods. In addition, beat-to-beat BP was measured continuously using the Portapres model 2 device to calculate stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR). There was systolic BP overshoot of > or = 15 mmHg after tilt reversal in 5 out of 8 PAF, but in only one of 8 MSA. A mean increase of systolic BP in PAF was significantly higher than that in MSA (p<0.01). TPR increased over baseline level after tilt reversal, although there was no significant difference. SV and CO levels during the post-tilt supine period were similar to baseline levels. In conclusion, BP overshoot was prominent in the PAF group but not in the MSA group. The phenomenon of BP overshoot while supine, especially in PAF, may have implications for long term cardiac and vascular damage in such patients.

Patients with syndromes of generalised autonomic failure often have extreme posture-related lability of blood pressure, with both orthostatic hypotension and recumbent hypertension. Whether these changes influence intraocular pressure (IOP) is not known. Mean arterial pressure (MAP) and IOP were measured in response to variations in posture between +45 degrees and -20 degrees in 8 normal subjects and 9 subjects with primary generalised chronic autonomic failure (AF). With postural change normal subjects showed minimal change in MAP (p=0.6) and small but significant changes in IOP (p < 0.001). Subjects with AF showed large and significant changes in both MAP (p < 0.001) and IOP (p < 0.001). Two AF subjects had raised IOP when recumbent, despite normal IOP at +45 degrees. There was significant covariance of MAP and IOP (p < 0.001 overall, p=0.004 in normal subjects, p=0.006 in AF subjects). However, individually, those patients with large changes in IOP could not be predicted from changes in MAP. These data show that patients with autonomic failure are subject to large posture-related changes in IOP. These appear to be related to the large posture-induced changes in systemic blood pressure which occur in these patients.

Continuous haemodynamic responses to head-up tilt (HUT) and its reversal were studied in 21 subjects with sympathetic denervation due to primary chronic autonomic failure; 10 had pure autonomic failure (PAF; peripheral failure) and 11 had multiple system atrophy (MSA; central failure); 8 healthy subjects (controls) also were studied. Supine systolic, diastolic and mean arterial pressure (MAP) and total peripheral resistance (TPR) were highest in PAF. The MAP response to HUT and tilt reversal were different between groups. After HUT, MAP increased in controls (12+/-4 mmHg), but decreased in PAF and MSA (41+/-4 & 19+/-4 mmHg respectively); the fall in PAF was greater than in MSA. With tilt reversal, MAP returned promptly, but not entirely to pretilt levels in controls, with small (insignificant) overshoots in MSA and PAF. The TPR response to HUT and tilt reversal was different between groups. After HUT, TPR increased in controls (0.31+/-0.04 PRU), decreased in PAF (0.23+/-0.1 PRU) and was unchanged in MSA. With tilt reversal, TPR remained elevated (15 %) above baseline in the controls and rose in PAF (13 %) with no change in MSA. There were no differences in supine heart rate (HR), stroke volume (SV) or cardiac output (CO) between the three groups; HR, SV or CO responses to HUT or tilt reversal also did not differ between the groups. Thus, after HUT, MAP decreased, with greater hypotension induced in PAF than MSA. Since CO did not differ between groups, the decrease in TPR appears to account for the greater fall in BP in PAF than in MSA. The elevated TPR at rest pre-tilt and after tilt reversal probably contributed to supine hypertension in PAF. These haemodynamic observations may aid therapeutic strategies to reduce orthostatic hypotension and prevent supine hypertension.

Abstract: In pure autonomic failure (PAF) – a rare form of primary dysautonomia – some patients show cerebrovascular lesions usually found in hypertensive subjects. In an autonomic laboratory records of patients with a definitive diagnosis of PAF having had cerebral imaging (cMRI, cCT) were analysed retrospectively. Tilt table data (supine/tilted), 24hour blood pressure recordings (day/night) and serum catecholamine levels were correlated with cerebrovascular lesions and also compared to published normal values. 50 PAF patients (23 female, 27 male) were identified, mean age 67years (sd 9.5). Out of these 35 (70%) had pathologic cerebral scans showing white matter lesions (WML) in 30, lacunar strokes in 5 and hemispheric stroke and microbleeds each in 1. Age and supine systolic blood pressure were significantly elevated in patients with pathologic scans (70 compared to 61years [p=0.007], and 170 compared to 154mmHg [p=0.045]). Out of 28 patients with WML and ambulatory blood pressure recordings available 24 were non-dippers. The data show that the frequency of WML is lower in PAF patients aged 60 to 80years compared to age matched community based samples. Although PAF usually results in hypotension, a frequent complication is supine hypertension. Although the overall frequency of WML seems to be reduced in PAF, a number of patients with elevated supine systolic blood pressure (>160mmHg) develop WML and some of these suffer stroke. [Copyright &y& Elsevier]