Diagnosis of PN is based on symptoms (what people feel
and tell their doctors about) and signs (physical indications noticed by a
doctor during an exam). Certain neurological tests are carried out in some
centres in order to distinguish HIV PN from PN resulting from its many other
possible causes including:
- Diabetes or insulin resistance
- Heavy alcohol consumption
- Thyroid disease
- Syphilis
- Kidney disease
- Vitamin B12 deficiency
- Other infections (shingles, CMV).
Neuropathy related to HIV or antiretrovirals usually
affects both sides of the body symmetrically, whereas other types may not. When
investigating pain symptoms, doctors routinely check for these other
conditions. If any are diagnosed, they can be treated.
“When a diagnosis of HIV PN is made,” Dr Cox says, “we
would start by explaining what HIV PN is, how it may have been caused and what
to expect.” Then the first goal is to prevent further damage by identifying any
aggravating factors and trying to control or eliminate them. This includes
proper management of the HIV infection. Neurotoxic drugs are identified and
stopped or replaced with a safer alternative if possible. In addition to the d-drug
antiretrovirals, other potentially neurotoxic drugs used in HIV include dapsone
(for PCP prophylaxis), isoniazid and ethambutol (tuberculosis drugs),
thalidomide (a treatment for apthous ulcers, or canker sores, in the mouth) and
certain cancer drugs.
At present we don’t know how to cure or reverse
neuropathy: attempts to develop therapies that promote the regeneration of
destroyed nerves have so far failed. Dr Cox says: “We explain that we cannot
reverse the condition and that treatments we offer will be to mask the
symptoms.”
Treatment options for neuropathic pain can be grouped
into five broad classes: anticonvulsants; antidepressants; non-specific
analgesics; topical treatments; and complementary therapies. However, Dr Cox
adds, “In terms of treatment, many of the usual treatments for pain in
neuropathy have been shown not to work in HIV PN.” Moreover, there are no
treatment options for other symptoms of PN, such as numbness or tingling.
In 2010, a systematic review and meta-analysis
co-authored by Dr Cox reported on the results of 14 prospective,
double-blinded, randomised, placebo-controlled trials of treatment options for
HIV PN.5 The authors concluded that only two available treatments – smoked
medicinal marijuana and high-dose topical preparations of capsaicin
– showed
efficacy.6 Marijuana needs no introduction; capsaicin is the active
ingredient in chilli peppers and is used in many topical painkilling
preparations such as Qutenza, where its pain-stimulating effect
paradoxically seems to overwhelm the signals that cause chronic pain.7
First-line treatments, including the anticonvulsants lamotrigine, pregabalin
and gabapentin (see below), tricyclic antidepressants such as amitriptyline, the
anti-arrhythmic drug mexiletine, the amino acid (and popular supplement)
acetyl-L-carnitine and low-dose topical capsaicin (0.75%) were no better than
placebo at decreasing PN pain in people with HIV.
While the systematic review and meta-analysis results
showed no efficacy with many treatments, they may still have some merit. Some
drugs may work for some individuals. Also, combining treatments, which is
common, may result in at least partial relief. Doctors will prescribe familiar
painkillers first before moving on to stronger ones such as opiates and
PN-specific medications such as amitryptiline.
The value of doing your own research is that you can walk into a doctor's appointment strengthened by knowledge. Dave R
Dr Cox also advises her patients on how to live with
PN day to day. “We point out the particular problems associated with loss of
ability to distinguish when something is hot and how it is important to test
bath temperature with an elbow rather than feet. We advise individuals to inspect
the bottom of their feet for damage and be very careful breaking in new shoes.
I usually suggest they avoid walking barefoot.”
Dave has tried six different drugs alone or in
combination, and all have been “unsuccessful in taming the pain”. He is weaning
himself off oxycodone, preferring for now to live with the pain: “I try to
mentally control the pain and relax as much as possible plus accept that the
pain is there and not try to fight it by tensing up or becoming too depressed.”
In addition to managing the pain, learning about the
condition has also helped Dave. “Very early on, I was more than a little
frustrated at the lack of information available to HIV patients with
neuropathy,” he recalls. So he set up a website, originally in Dutch and now
also in English, along with a blog to provide information about neuropathy,
from which people can make their own decisions and ask their own questions
while sharing the experiences of others. The blog is available at www.neuropathyandhiv.blogspot.com.
According to Dave, “The value of doing your own
research is that you can walk into a doctor’s appointment strengthened by
knowledge and maybe not be so confused when you walk out. Neuropathy is not an
easy thing to explain; if you have some idea beforehand it will help
enormously.”
Finally, Dave points out the importance of a support
network. “Having chosen wisely, make friends of your two main healthcare
providers: your home doctor [GP] and your HIV specialist. It’s a long journey
with neuropathy; you need to have someone on your side who knows what you and
they are talking about.”
As for family and friends, he adds, “They won’t
understand what’s happening to you and possibly after several weeks of moaning,
will be distinctly unsympathetic too. If possible, take a family member or a
friend with you to a consultation with your doctor. It’s vital that you’re
taken seriously because, otherwise, you can feel very lonely while you’re
suffering. You’re going to need a listening ear or a shoulder to cry on at some
stage in the future.” Sound advice, indeed.