Cardiovascular and hormonal responses to food ingestion in humans with spinal cord transection

Treatment of postprandial hypotension with acarbose in an adult with cervical spinal cord injury: a case report

INTRODUCTION

Postprandial hypotension is a type of autonomic dysfunction where there is a decrease in systolic blood pressure of >20 mm HG within 2 h after eating thought to be due to poor cardiovascular compensation for splanchnic blood pooling that occurs with meals. This form of autonomic dysfunction is underdiagnosed in patients with spinal cord injury, likely in part because it can be asymptomatic.

CASE PRESENTATION

26-year-old with complete cervical spinal cord injury (SCI) presented with neck pain described as severe 10/10 pain, which felt like "a rope around his neck." Pain came on during and after meals and was associated with a feeling of pressure behind his eyes, white spots in his vision along with feeling as if he was going to pass out. The caregiver noted a systolic blood pressure drop by about 30-40 points with meals and lost weight due to avoiding eating. A diagnosis of post-prandial hypotension (PPH) was made and Acarbose was started at a low dose 25 mg three times per day with meals. During follow up, the patient reported complete resolution of drops of blood pressure, neck pain, and all associated symptoms. The patient was able to eat comfortably and gained weight.

DISCUSSION

There are few case reports on PPH in SCI and none looking at acarbose on a young, nondiabetic person with SCI. Clinicians should be aware that PPH can occur in young otherwise healthy people with SCI. Further research is needed on PPH, including the use of acarbose, in the SCI population.

Postprandial Hypotension: An Underreported Silent Killer in the Aged

Orthostatic hypotension (OH) is one of the most common autonomic dysfunctions, with high prevalence in populations of elderly, hypertensive, diabetic, or Parkinson's patients. Evidence is emerging that OH co-occurs with postprandial hypotension (PPH); a greater prevalence of PPH than of OH is reported for Parkinson's disease patients. OH is diagnosed by measuring the blood pressure changes associated with postural changes and often produces alterations in consciousness or other such bothersome symptoms as fainting. PPH is diagnosed by measuring the blood pressure changes associated with ingesting high carbohydrate test meals. Because of the time lag between food ingestion and absorption, PPH is often not reported as symptomatic and, therefore, not diagnosed as PPH. OH and PPH are independent predictors for all causes of mortality. Relative underdiagnosis may qualify PPH as a "silent killer" disease. This review is aimed at providing updates on the epidemiology, pathophysiology, and clinical aspects associated with the diagnosis and treatment of PPH. Highlighting the current gaps in knowledge and research about PPH is expected to make medical practitioners more cognizant of the dangers of underdiagnosis and motivate future research to identify individuals and populations at high risk for PPH and its sequelae.

Postprandial Hypotension and Spinal Cord Injury

Postprandial hypotension (PPH) is defined as a fall of ≥20 mmHg in systolic blood pressure (SBP) or a SBP of <90 mmHg after having been >100 mmHg before the meal within two hours after a meal. The prevalence of PPH among persons with spinal cord injury (SCI) is unknown. Ambulatory blood pressure measurement was performed in 158 persons with SCI, 109 men, median age was 59.1 years (min.:13.2; max.: 86.2). In total, 78 persons (49.4%) had PPH after 114 out of 449 meals (25.4%). The median change in SBP during PPH was −28 mmHg (min.: −87; max.: −15 mmHg) and 96% of the PPH episodes were asymptomatic. The occurrence of PPH was correlated to older age (p = 0.001), level of injury (p = 0.023), and complete SCI (p = 0.000), but not, gender or time since injury. Further studies are needed to elucidate if PPH contributes to the increased cardiovascular mortality in the SCI population.

Postprandial hypotension: a systematic review

BACKGROUND

Postprandial hypotension (PPH) is an important clinical problem, which has received inappropriately little attention.

METHODS

A systematic search of the databases PubMed, Embase, Cochrane Library, and Web of Knowledge, from their inception to the present time, was conducted to identify studies relevant to the epidemiology, pathophysiology, and/or management of PPH.

RESULTS

A total of 417 full-text papers were retrieved from database searching and, following screening, 248 were retained. Of these, 167 papers were considered eligible for inclusion.

CONCLUSIONS

PPH occurs commonly in older people and represents a major cause of morbidity. Although the pathophysiology of PPH remains poorly defined, diverse factors, including impairments in sympathetic and baroreflex function, release of vasodilatory peptides, the rate of small intestinal nutrient delivery, gastric distension, and splanchnic blood pooling, appear important. Current pharmacologic and nonpharmacologic management is suboptimal. Research into the pathophysiology of PPH represents a priority so that management can be targeted more effectively.

Hemodynamic responses to head-up tilt after spinal cord injury support a role for the mid-thoracic spinal cord in cardiovascular regulation

BACKGROUND

Data showing a role for the mid-thoracic spinal cord (SC) in the control of hemodynamic changes is scarce despite existing evidence for its involvement in autonomic regulation.

STUDY DESIGN

On the basis of the open label prospective series comparing three groups.

OBJECTIVE

To determine whether the mid-thoracic SC has a role in hemodynamic regulation during head-up tilt (HUT).

SETTING

Spinal Research Laboratory, Loewenstein Rehabilitation Hospital.

METHODS

A total of 13 healthy control subjects, 10 patients with T(4)-T(6) paraplegia and 11 with C(4)-C(7) tetraplegia were examined during supine rest and during HUT. Heart rate (HR), blood pressure (BP), HR spectral components (lower frequency fluctuation (LF), higher frequency fluctuations (HF) and LF/HF) and cerebral blood flow velocity (CBFV) were continuously measured or calculated.

RESULTS

BP response to HUT differed among these groups (P<0.02). During HUT, BP decreased markedly in the tetraplegia group (from a mean value of 81.65 to 67.69  mm Hg), and increased in the control groups (from 92.89 to 95.44 mm Hg) and in the T(4)-T(6) paraplegia group (from 96.24 to 97.86 mm Hg). Significant correlation was found in the control and tetraplegia groups between increases in HR LF/HF and HR at HUT (r>0.7; P<0.01). No such correlation was found in the paraplegia group. HUT effect on HR and CBFV was significant in all groups (P<0.001), but group differences were statistically non-significant.

CONCLUSION

Findings were generally compatible with those of comparable previously published studies, but they also support a role for the mid-thoracic SC in hemodynamic regulation, which should be considered in clinical setting and in research.

The isolated sympathetic spinal cord: Cardiovascular and sudomotor assessment in spinal cord injury patients: A literature survey

OBJECTIVES

To present a comprehensive approach to the assessment of the severity of the autonomic lesion in spinal cord injury (SCI) patients, with regard to the level of lesion. To discuss how to assess an isolated sympathetic spinal cord that has lost supraspinal control (sympathetically complete lesion).

METHOD

PubMed was searched for articles related to cardiovascular (mainly cold pressor test, respiratory and postural challenges) and sudomotor (sympathetic skin responses) tests that have been used. The results of these evaluations are analysed with regard to the site of stimulation (above or below the lesion) according to three types of SCI that offer typical autonomic reactions (tetraplegics, paraplegics at T6 and at T10).

RESULTS

Non-invasive cardiovascular and sudomotor testing allows the assessment of the isolated sympathetic spinal cord in SCI patients. Typical responses are found in relation with the level of the sympathetic lesion. Its definition would allow comparison with the somatic motor and sensory level of lesion of SCI patients and provide additional aid to the classification of those patients.

CONCLUSION

For research purposes on the integrity of the spinal sympathetic pathways, a battery of test approach is probably needed, using a combination of stimuli above and below the lesion, evaluating both cardiovascular and sudomotor pathways.

Hemodynamic effects of liquid food ingestion in mid-thoracic paraplegia: is supine postprandial hypotension related to thoracic spinal cord damage?

BACKGROUND

Postprandial hypotension (PPH) appears in various conditions with autonomic failure and was symptomatic in a patient with thoracic paraplegia, but was not remarkable in patients with tetraplegia.

OBJECTIVE

To determine whether the pathology causing PPH may include a thoracic but not a cervical spinal cord lesion (SCL).

DESIGN

An experimental controlled study.

SETTING

The spinal research laboratory, Loewenstein Hospital, Raanana, Israel.

SUBJECTS

Thirteen healthy subjects, 10 patients with traumatic T(4)-T(6) paraplegia, and 11 patients with traumatic C(4)-C(7) tetraplegia.

MAIN OUTCOME MEASURES

Heart rate (HR), blood pressure (BP), HR and BP spectral components (LF, HF, LF/HF), cerebral blood flow velocity (CBFV), and cerebrovascular resistance index (CVRi).

METHODS

The effects of a standard liquid meal on the outcome measures were compared between the three subject groups monitored for HR, BP, and CBFV, from 55 min before to 45 min after the start of the meal. The recorded signals were digitized online and analyzed off-line in the time and frequency domains.

RESULTS

After meal, BP decreased only in the paraplegia group (P<0.01), HR increased more prominently in this group (P<0.01), CVRi tended to decrease only in the paraplegia group, CBFV did not change significantly in any group, and HR LF/HF increased (P<0.001) in all groups but tended to increase more in paraplegia.

CONCLUSIONS

Patients with mid-thoracic SCL may develop PPH. The pathology causing PPH can include a thoracic but not a cervical SCL. The normal hemodynamic reaction to liquid meal ingestion is mediated through the mid-thoracic spinal cord. The sympathovagal balance increases after food ingestion, more prominently in patients with PPH, and cerebrovascular resistance changes during PPH may help maintain the cerebral circulation.

Orthostatic hypotension and paroxysmal hypertension in humans with high spinal cord injury

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.

The prevalence and association of neck (coat-hanger) pain and orthostatic (postural) hypotension in human spinal cord injury

OBJECTIVE

To investigate the prevalence of orthostatic (postural) hypotension (OH) and neck pain in a 'coat-hanger' occipito-cervical distribution in subjects with spinal cord injury (SCI), and their association.

METHOD

Blood pressure was measured during head-up tilt to 60 degrees (to determine OH) and neck pain was assessed in 28 subjects with SCI (cervical, thoracic and lumbar level) with McGill Pain Questionnaire, visual analogue scale for pain intensity and Orthostatic Intolerance Symptoms Questionnaire for pain frequency.

RESULTS

Neck pain was reported by 53.6% of subjects. Orthostatic hypotension was present in 57.1% of subjects. Neck pain was reported by 75% of subjects with OH and 25% of subjects without OH (P<0.03, Chi-square). Features of such pain included positive correlation to upright posture and exercise, and relief when lying flat.

CONCLUSION

There is a high prevalence of neck pain and OH in SCI, with a positive association similar to that reported in primary autonomic failure with OH.

Static exercise-induced increase in blood pressure in individuals with cervical spinal cord injury

OBJECTIVE

To compare the pressor response to static exercise in subjects with cervical spinal cord injury (SCI) at the C6 to C8 level with that in able-bodied control subjects. In these SCI subjects, the descending supraspinal sympathetic neurons and afferent pathways from the contracting muscles to peripheral vessels via the medullary cardiovascular center are damaged.

DESIGN

Mean arterial blood pressure, heart rate, and plasma concentrations of norepinephrine, epinephrine, renin activity, vasopressin, aldosterone, and human atrial natriuretic peptide were measured during a 2-minute period of sustained contraction of elbow flexor group muscle in 7 SCI subjects and 7 age-matched able-bodied control subjects.

RESULTS

Static exercise resulted in a significant increase in mean blood pressure (p<.05) in both SCI subjects (pre-exercise. 74.7+/-2.2 mm Hg; static exercise, 81.9+/-4.1 mm Hg) and control subjects (pre-exercise, 101.0+/-4.2 mm Hg; static exercise, 117.0+/-4.9 mm Hg). In SCI subjects, there was no change in heart rate during exercise, whereas in control subjects heart rate increased during exercise (p<.05) (pre-exercise, 8.7+/-3.8 beats/min: static exercise, 76.0+/-3.1 beats/min). There were no significant changes in the hormone levels in the SCI subjects throughout the experiment.

CONCLUSION

The significant increase in mean blood pressure observed in the present study indicates the presence of peripheral control from muscle receptors and evoked pressor response during static exercise in SCI subjects.