Nocturnal Hypertension and Autonomic Dysfunction Due to Human T-Lymphotropic Virus Type-1 (HTLV-1) - associated Myelopathy / Tropical Spastic Paraparesis (HAM/TSP)
Dr S M S Raza, MB BS,MD Clinical Registrar in Cardiology, The Royal Liverpool and Broadgreen University Hospitals NHS Trust, Liverpool, UK.
Dr J R Pyatt, MB ChB, BSc, MRCP, Consultant Cardiologist, The Royal Liverpool and Broadgreen University Hospitals NHS Trust, Liverpool, UK.
Human T-lymphotropic virus type-1 (HTLV-1) - associated myelopathy (HAM) or tropical spastic paraparesis (TSP) is a rare disorder characterised by slowly progressive spastic paraparesis, spincter disturbances, and minimal sensory loss. Cardiovascular dysautonomia also occurs altering normal circadian rhythms of blood pressure and heart rate. We report a West Indian patient with HAM/TSP that had nocturnal hypertension observed on 24-hour ambulatory blood pressure monitoring (ABPM) together with autonomic dysfunction resulting in poorly controlled hypertension and cancellation of elective surgery. Reversed circadian blood pressure rhythm should be considered in HAM/TSP patients and associated with increased risk of vascular events.
Human T-lymphotropic virus type-1 (HTLV-1) - associated myelopathy (HAM) or tropical spastic paraparesis (TSP) is a rare disorder characterised by slowly progressive spastic paraparesis, spincter disturbances, and minimal sensory loss occurring in less than 5 % of patients infected with HTLV-1. It has a particularly high prevalence in Japan, the West Indies and amongst Iranian Jews. More rarely, and in addition to myelopathy, autonomic dysfunction can occur. Cardiovascular dysautonomia predominantly involves sympathetic nerves (1) and can occur subclinically to alter normal circadian rhythms of blood pressure (BP) and heart rate (HR) in HAM/TSP patients (2).
We report an interesting and clinically significant trend observed on 24-hour ambulatory blood pressure monitoring (ABPM) in a West Indian patient with HAM/TSP who also demonstrated autonomic dysfunction.
Our patient was a 73-year old Jamaican woman who was first diagnosed with HAM/TSP in 1991. She was referred by her general practitioner for better control of her BP as she had had two elective orthopaedic operations cancelled due to uncontrolled high BP. On both occasions surgery was planned for a morning list. Her medications included losartan and long acting nifedipine. A screen for secondary causes of hypertension including testing for phaeochromocytoma was negative. As her BP had also been poorly controlled previously (ranges: 120 - 165 mmHg systolic and 70 - 90 mmHg diastolic) 24-hour ABPM was performed. The recording is illustrated in figure 1 and the BP profile shows mainly nocturnal hypertension (and confirmed on a second subsequent recording some months later) with gradual improvement of a BP during the daytime. The average day interval between 8:00 and 21:59 was 129/67 mmHg (normal: < 135/85) and the average night interval between 22:00 and 7:59 was 144/76 mmHg (normal: < 120/75). Heart rate was also higher during the night interval than during the day interval.
Cardiovascular autonomic function testing showed no heart rate variation with either deep inspiration/expiration (ratio: 1:0.98) and valsalva (ratio: 1:0.97). Neither lying/standing BP or heart rate were performed due to difficulty with prolonged standing.
The frequency and importance of dyautonomia in HAM/TSP are probably underestimated and when present predominantly affect the sympathetic nervous system (1). The circadian rhythms of BP and HR control were analysed by non-invasive monitoring in 23 patients with HAM/TSP and 23 controls (2). In both groups circadian rhythms of BP and HR were present. However, the HAM/TSP group exhibited significantly lower BP amplitudes and 24-hour mean systolic and diastolic readings than in the control group. The differences in the acrophases of the systolic and diastolic BPs and HR were small but significantly different with higher nighttime values as seen in with our patient although in contrast to this study she had a much more pronounced increase in her night time BP.
Blood pressure normally follows a circadian pattern with values peaking during the daytime hours and falling to a nadir after midnight (3,4). Reversed circadian BP rhythm is associated with abnormal cardiovascular reflexes in diabetic subjects (5) and independently of advanced microvascular complications increases the risk of both fatal and non-fatal vascular events (6). Whilst in older hypertensive Japanese men, the presence of reversed nocturnal systolic BP fall significantly increased the risk of intracranial haemorrhage in comparison to those who "dipped" or failed to change their systolic BP at night (7). This is thought to be mediated through site-specific injury to the brain resulting in impaired central autonomic nervous system functioning (8). Thus abnormal cardiac autonomic dysfunction was demonstrated in our patient who had at least two abnormal responses (HR during deep breathing and valsalva). indicating reduced parasympathetic tone. The importance of nocturnal BP control is also germane to the finding of increased incidence of myocardial infarction from 06:00 to 08:00 in non-diabetics (9).
In order for her to achieve
the desired BP level to allow elective surgery she could change her antihypertensive
dosing interval to the evening (10) and have her surgery performed in the afternoon
when her BP is at its lowest.
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Address for correspondence:
Dr S M S Raza
Clinical Registrar in Cardiology
The Royal Liverpool and Broadgreen University Hospitals NHS Trust
Tele: 44 (0)151 706 2000
Fax: 44 (0)151 706 5833