Idiopathic Neuropathy A Worrying Diagnosis

Today's post from kevinmd.com (see link below) talks about idiopathic neuropathy which is basically neuropathy for which no clear cause can be found. Many people with neuropathy symptoms go to their doctors, undergo a series of tests (also outlined below) and although the diagnosis of neuropathy is made, the tests don't reveal what caused it. This is hardly surprising when there are more than 100 possible causes of nerve damage and many people have more than one condition that may be responsible for their symptoms. A diagnosis of idiopathic neuropathy can be very unsatisfying and worrying for a patient, especially if they feel that they're perhaps not being believed or taken seriously but it is a genuine diagnosis and takes nothing away from the fact that you have neuropathy - it's just they can't positively identify the cause.

Idiopathic neuropathy: 2 steps providers can take

SHANNA K. PATTERSON, MD | FEBRUARY 10, 2013

It is estimated that over 20 million Americans have neuropathy. Many people don’t know that prior to the advent of the obesity pandemic and the associated rising rates of diabetes, leprosy was the most common cause of neuropathy worldwide. Although it is now widely recognized that diabetes is the most common cause of neuropathy, for up to 30% of patients the cause of their neuropathy remains unknown. These cases are dubbed “idiopathic,” and – as a neuropathy specialist I assure you – that for many patients this becomes a chronic source of frustration and anxiety.

Some of the questions I hear from idiopathic neuropathy patients include:

What are the chances my neuropathy will get worse?
Isn’t there any treatment?
What else can be done to find the cause of my neuropathy?

It is almost impossible to address these issues without a more specific neuropathy diagnosis.

Diagnosing neuropathy is a two-step process. First, the diagnosis of neuropathy is confirmed. This should include identifying the population of nerves involved, the type of nerve pathology, and the distribution of nerve pathology. Detailed electrodiagnostic testing (electromyography and nerve conduction studies), and possibly a skin biopsy (to detect the involvement of small fiber nerves) or autonomic testing (to detect the involvement of autonomic nerves) may be required. Second, the cause for the neuropathy can be explored, starting with blood tests. In some cases a nerve biopsy or genetic testing may be needed. The more specific the characterization of the neuropathy, the easier it is to know how to look for what might be causing it.

I would argue that for any idiopathic neuropathy patient whose symptoms affect daily activities – whether that is because of pain, weakness, imbalance, or difficulty walking – further steps should be taken to help search for a more specific diagnosis.

Two steps that every health care provider can take include:

Making sure your patient is seen by a neuropathy specialist. A neuropathy (or neuromuscular) specialist is a sub-specialized neurologist. These clinicians can sometimes uncover less common causes of neuropathy such as hereditary, toxic, autoimmune, and paraneoplastic etiologies. They can also more readily discern when a patient might have a more unusual presentation of a common form of neuropathy.

Asking how long it has been since your patient had a neuropathy evaluation. In cases where patients were evaluated for neuropathy a number of years ago, a referral for a repeat evaluation can help determine the underlying cause of neuropathy and guide treatment choices. In some cases the underlying cause of neuropathy may not be evident even after further evaluation, but on-going research helps us to learn more about neuropathy’s various causes, develop new tests, and consider new treatment approaches. Also, for some patients, interval electrodiagnostic testing can help clarify the diagnosis, especially if the neuropathy is progressing.

Hopefully these points can help idiopathic neuropathy patients obtain the clarity they seek and the medical care they need.

Shanna K. Patterson is a neurologist and serves on The Neuropathy Association’s Medical Advisory Committee.
http://www.kevinmd.com/blog/2013/02/idiopathic-neuropathy-2-steps-providers.html

More HIV Children With Neuropathy

Today's post from i-base.info (see link below) is a reflection on one of the topics discussed at the 2012 Aids Conference in Washington. We often forget that although neuropathy is relatively rare in children in the western world, old-fashioned HIV drugs, which are still used widely in the third world (mainly because those are the only ones the drug companies are prepared to make price concessions on) cause many more cases in poorer countries. These drugs are renowned for causing peripheral neuropathy as a side effect and of course, there will be a high percentage of HIV positive children who are going to be affected. One can only conclude that political, budgetary decisions need to be made to change the situation.

High prevalence of peripheral neuropathy in children taking d4T in rural South Africa

1 August 2012. Polly Clayden, HIV i-Base

Peripheral neuropathy is a well-known side effect of older nucleosides, particularly d4T, which is still used widely in poor settings.

Although it clearly occurs, this phenomenon is less well characterised in children and it is difficult to assess, particularly with limited resources.
In an oral presentation at IAC 2012, Remco Peters from the Anova Health Institute, Khutso Kurhula Project, Tzaneen, South Africa, showed findings from an evaluation of neuropathy in children in the rural Mopani district. This district is a health priority area in South Africa and the institute runs a nurse managed ART programme in 100 public health care facilities with the support of PEPFAR.
The group used two clinical tools to screen for neuropathy – the neuropathy symptom score (NSS) and neuropathy disability screen (NDS). These tools are feasible for resource limited settings and the NDS only uses a reflex hammer, cotton buds, tooth pick and cold water (to access ankle reflex and perception of vibration, pin-prick and temperature).

It was a cross sectional study of 182 children of median age of 9 years (range 5-15 years) and receiving ART for a median of 2 years (range 2 months to 6.4 years). The majority (86%) received d4T-containing regimens.
Forty-nine (27%) children reported neuropathy symptoms and NDS was positive for 25 children (14%); 43 (25%) children fulfilled the study criteria for peripheral neuropathy.

Co-trimoxazole use was negatively associated with neuropathy OR 0.42, (95% CI 0.20 – 0.88, p=0.019) and there were trends for peripheral neuropathy to be associated with older age and longer time on ART but this analysis is still onging.

Dr Peters included quotes from the children: “My feet are burning, I must take off my shoes in class otherwise I can’t concentrate” from one and, “I can’t sleep at night because of the tingling of my feet; I’m tired during the day” from another.

He concluded that neuropathy is common and frequently undiagnosed in this region and that NSS and NDS are useful diagnostic tools in such settings. Most importantly he added: “Talk to the child!”

comment

d4T associated toxicities have been well documented and screening tools that can be used where resources are limited are welcome.
That children’s experience of adverse events reliant on patient reporting often seems to increase as they get older (and gain a vocabulary) is worth noting.

Reference:

Peters RPH et al. Clinical screening shows high prevalence of peripheral neuropathy in children taking antiretroviral therapy in rural South Africa. 19th International AIDS Conference. 22-27 July 2012, Washington. Oral abstract MOAB0205.

http://i-base.info/htb/19847