Neurology clinic - autonomic neuropathy
Dr Mark Ritchie, a GPSI in pain management, discusses a Parkinson’s patient with signs of autonomic neuropathy
A 66-year-old man is known to have a diagnosis of Parkinson’s disease. At first presentation a year previously, he had a resting tremor, mild bradykinesia and some rigidity. No postural instability was present. The diagnosis was confirmed by a consultant neurologist and he was started on levodopa.
His initial symptoms have improved on therapy but he now presents complaining of dizziness, loss of appetite and constipation. On questioning, it is clear that vertigo is not the diagnosis and that the ‘dizziness’ occurrs on postural change. With respect to his appetite, he says he always feels full and is often constipated. He mentions that erectile dysfunction is also bothering him. He says these symptoms have gradually become a problem.
On examination there are no significant findings except that his blood pressure shows variation from sitting to standing. Physical genital examination is normal. Current medications include levodopa, simvastatin 40mg od, and occasional paracetamol for mechanical back pain. The symptoms cannot be attributed to these medications.
Blood tests, including a FBC, U&E, LFT, TFT, glucose, testosterone and vitamin D are also normal. His total cholesterol is 5.9mmol/L. The blood tests show no metabolic cause for the symptoms.
Autonomic neuropathy seems to be a likely diagnosis. There are other possible causes for these symptoms as they are quite general, hence the need for blood tests and medication reviews.
The diagnosis is confirmed by the neurologist at his Parkinson’s review. He is started on a PDE5 inhibitor and metoclopramide for bowel motility.
He is advised on how to avoid sudden postural changes and will be reviewed in a few months’ time.
Autonomic neuropathy is a group of symptoms (not a specific disease) that occur when there is damage to the nerves that carry information from the brain and spinal cord to the heart, bladder, intestines, sweat glands, pupils and blood vessels to manage normal daily bodily functions.
Autonomic neuropathy is not unique to Parkinson’s and may be seen in alcohol misuse, diabetes, Guillain-Barré syndrome, multiple sclerosis, spinal cord injuries and after spinal surgery. This list is not exhaustive.
Symptoms can include:
• Early satiety.
• Cardiovascular autonomic neuropathy can lead to:
– Postural/orthostatic hypotension.
– Resting tachycardia and exercise intolerance.
– Silent myocardial infarction (for instance, in diabetes).1
• Incomplete bladder emptying.
• Difficulty initiating micturition.
• Sweating can be excessive or decreased, which affects the patient’s ability to regulate body temperature.2
• Sexual dysfunction – erectile dysfunction in men and vaginal dryness in women.
A simple test that can be performed in general practice is postural blood pressure measurement.
This test involves a few simple steps:
• The patient should lie down for five minutes.
• Then blood pressure and pulse are measured.
• The patient then stands and pulse and blood pressure are taken after one minute, and again after three minutes.
A systolic drop of greater than or equal to 20mmHg or a diastolic drop of 10mmHg or greater, with a feeling of lightheadedness or dizziness, are abnormal and considered to be signs of postural hypotension (orthostatic hypotension).
On standing, a drop in blood pressure is normal. The body’s response will be to constrict blood vessels automatically and increase heart rate. In autonomic neuropathies this may be slowed and can then be seen in the above test.
The results are not always clear and so referral and further testing may be necessary. This test is specific to orthostatic hypotension and not to autonomic neuropathies, and other causes will have to be excluded – for instance, medications such as ACE inhibitors.
Other tests for autonomic neuropathy are usually performed in secondary care and can include:
• The tilt table test for postural blood pressure.
• Gastric emptying tests to check for slowed movement of food, delayed emptying of the stomach and other abnormalities (usually done by a gastroenterologist).
• Sweat gland testing.
• Urodynamic testing to evaluate urinary function.
The tests done will depend on the presenting symptoms.
Reversal of nerve damage is not usually possible. Treatment is therefore aimed at managing symptoms, attempting to prevent future problems and encouraging patient self-care. The treatments will depend on which symptoms are problematic.
Treatments can include increasing dietary salt or giving salt tablets to increase fluid volume in blood vessels, medications for arrhythmias, a pacemaker, sleeping with a raised head or wearing elastic stockings.
A number of medications can be used for the management of intestinal motility disorders. Examples are neostigmine, metoclopramide and loperamide.3 Small, more frequent meals may also help.
Medicines and self-care programmes can help with urinary incontinence, erectile problems and neurogenic bladder problems. Early diagnosis and treatment increase the likelihood of controlling symptoms.
Risks with autonomic neuropathy
• Autonomic neuropathy can hide the signs of a heart attack, which may therefore present with sudden fatigue, sweating, shortness of breath, nausea and vomiting rather than chest pain.
• Fluid and electrolyte imbalances.
• Falls due to postural hypotension can lead to injury.
• Urinary problems, including difficulty starting urination, urinary incontinence and an inability to completely empty the bladder, can lead to urinary tract infections.
• Impotence can have social effects.
Patients can be advised and encouraged to:
• Avoid sudden postural changes.
• Take appropriate dietary advice, smaller, more frequent meals and good fluid intake.
• Report functional bladder and bowel changes.
• Report sexual dysfunction.
• Report faintness or light-headedness.
Dr Mark Ritchie is a GPSI in pain management in Swansea
This article was commissioned with the Primary Care Neurology Society. Their mission is to support provision of neurology education and information across primary care in order to improve delivery of care to people with neurological conditions. For just £45, you can access a range of resources from www.p-cns.org.uk, including free access to Europe’s leading online neurosciences e-learning resource, E-Brain.
1 Vinik AI, Maser RE, Mitchell BD et al. Diabetic autonomic neuropathy. Diabetes Care, 2003;26:1553-79
2 Mayo Clinic staff. Autonomic neuropathy, 2012. Mayo Foundation for Medical Education and Research. Available at mayoclinic.org/diseases-conditions/autonomic-neuropathy/basics/symptoms/con-20029053
3 Kuwajerwala NK. Intestinal motility disorders medication, 2013. Medscape. Available at: emedicine.medscape.com/article/179937-medication
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• Hauser RA, Benbadis SR. Parkinson disease. Medscape, 2013
• NICE. CG35: Parkinson’s disease – diagnosis and management in primary and secondary care. London: NICE; 2006