Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is as complicated to articulate, as it is to manage. CIDP is the result of an inflammatory attack against myelin, the fatty layer that encases large nerves. The damage to the myelin sheath considerably slows down the speed at which nerves transmit electrical impulses. This leads to limb weakness, sensory impairment, and a host of other symptoms.
The diagnosis of CIDP is made on the basis of a clinical examination, nerve conduction studies (NCS), spinal fluid analysis, and countless blood tests. If this convoluted diagnostic process is hair-tearing, the treatment is even more perplexing.
There are 2 major CIDP treatment conundrums. The first is whether to start the treatment with steroids, or with intravenous immunoglobulins (IVIg). The second conundrum is what to do when the patient fails to respond to both of these first line CIDP treatments. Two recent papers have now come to the rescue, and they hope to settle, once and for all, these two major neurological puzzles.
1. Choosing steroids or IVIg as 1st line treatment
The first line treatment for CIDP is usually a toss-up between steroids and intravenousimmunoglobulins (IVIg). This is because neurologists had no way of telling who will do well on steroids, and who will respond to IVIg. Until now, that is. A recent report in the Journal of Neurology, Neurosurgery and Psychiatry (JNNP) set out to understand what patient characteristics predict response to IVIg. The authors studied >200 people with CIDP treated with IVIg, and reported that 1/4 did not respond. These IVIg non-responders had the following features:
The presence of pain
Association with other autoimmune diseases
A difference in the severity of weakness between the arms and the legs
The absence of anti-myelin associated glycoprotein (anti-MAG)
The authors conclude that people with CIDP who have the features above should start their treatment with steroids rather than IVIg. This surely beats tossing a coin.
2. Choosing rituximab as 1st line treatment
Choosing the 2nd line treatment of CIDP is comparatively easy; swap between IVIG and steroids, or go for plasma exchange (PE). Rituximab, a monoclonal antibody, is now also recognised as an effective treatment for CIDP. Conventional practice is to use this expensive treatment only when both IVIg and steroids fail. A recent paper however suggests that people with CIDP who also have IgG4 antibodies do not respond to either IVIg or steroids. On the bright side however, they do well when treated with Rituximab. The paper in the journal Neurology is titled Rituximab in treatment-resistant CIDP with antibodies against paranodal proteins. The authors studied only 4 patients, but the number was enough for them to suggest that patients with CIDP, who also have IgG4 antibodies, should be treated with Rituximab. Makes sense to me, if the alternative is predictable failure.
Now that some light has been shone on the treatment of CIDP, the next stage is to see how things work at the coal face. Do you have any feedback on CIDP treatment? Please leave a comment.
Motor neurone disease (MND) is, to say the least, dreadful. It also doesn’t help that the terminology neurologists use adds to the distress. West of the Atlantic, amyotrophic lateral sclerosis (ALS) means MND but goes eastwards and it is only a subtype of MND. Thankfully, for most Americans at least, there is no confusion; it is simply Lou Gehrigdisease.
MND however remains a conundrum for neurologists who are struggling to solve its puzzling riddles. MND researchers continue to toil and sweat, but their efforts are bearing fruits. Take for example the great strides that established the link between MND and the C9ORF72 gene. What are the promising prospects in the world of MND? Here are some.
Associations: Thiamine deficiency and Diabetes
Should we be on the lookout for thiamine deficiency in patients with MND? This question is prompted by an article in the JNNP which shows an unexpectedly high frequency of laboratory, but not clinical, thiamine deficiency. Titled Thiamine deficiency in amyotrophic lateral sclerosis, the paper reported thiamine deficiency in about 28% of subjects with MND. The authors did not impute any causal association, and there is nothing to suggest that replenishing the thiamine improved outcomes. It is still worth thinking about because people with MND, as the paper emphasised, are at risk of thiamine deficiency.
Will MND ever be a curable disease? A big question, but this is the vision of all the hard-working researchers in this field. What are the prospects for a cure? One group of researchers believe the answer is in preventing misfolding of TDP-43, the protein that plays an important role in MND. They set out their case in an article published in Neurotherapeutics titled TDP-43 Proteinopathy and ALS: Insights into Disease Mechanisms and Therapeutic Targets. And don’t worry, its free access. The bold abstract says it all: “we present the case that preventing the misfolding of TDP-43 and/or enhancing its clearance represents the most important target for effectively treating ALS”. The proof of the pudding….
Diagnostic test: Nerve ultrasound
Making the diagnosis of MND is not always (make that is hardly ever) straightforward. In the early stages, symptoms are vague, and clinical signs are non-specific. MND also has many mimics. One of such mimics is multifocal motor neuropathy (MMN). To distinguish this and other mimics from MND, neurologist rely on a test called nerve conduction study (NCS). Even this however is not always helpful.
Brain magnetic resonance imaging (MRI) is not a test neurologist rely upon to make the diagnosis of MND. Not anymore it seems, going by an article in American Journal of Neuroradiology. The paper is titled A Potential Biomarker in Amyotrophic Lateral Sclerosis. In the article, the authors assessed the amount of iron deposition in the brains of people with MND using the MRI techniques called SWI and DTI. Their findings suggest that the amount of iron in the motor cortex and motor tracts of the brain is a good guide to the presence of MND. If confirmed, this technique will help to reduce the long time it often takes before neurologists confirm their suspicions of MND to patients and their families.
The outcome of MND, poor as it often is, varies quite widely. This is influenced by several factors such as the type of MND, use of the medicine riluzole, and multidisciplinary care. New research suggests that neurofilament light chain (NfL) may be a more sensitive marker of prognosis. This is reported in an article published in Neurology titled Neurofilament light chain: A prognostic biomarker in amyotrophic lateral sclerosis. The authors demonstrated that patients with MND have much higher levels of NfL than those without the disease. Furthermore, subjects with MND who had the highest levels at the onset had a higher mortality hazard ratio. I think I know what that means.
Prognostic scale: ALS-MITOS predictive system
A paper in the JNNP has proposed a new predictive system for MND called ALS-MITOS, reportedly better than the more familiar ALSFRS-R. The report is titled The MITOS system predicts long-term survival in amyotrophic lateral sclerosis. Most practicing neurologists wouldn’t know the difference because they don’t to use such predictive systems. But MND researchers would be licking their lips at the prospect of a better measure of disease progression; it will make it much easier for them to show that their interventions really do work!
There are >100 mutations in the superoxide dismutase 1 (SOD-1), a gene known to cause MND. SOD-1 is an enzyme that binds both copper and zinc, and when defective it results in mutant copper (don’t worry, I’m just finding this out myself). Acting on this hypothesis, researchers came up with a crafty way of delivering normal copper into the central nervous system of mice modelled with SOD-1 MND. Publishing in Neurobiology of Disease, the authors showed how they achieved this with CuATSM, a chemical that contains copper and currently used for PET scans. CuATSM is readily transported into the nervous system, delivering its copper as it does so.
Every recalcitrant disease is today threatened with gene therapy. Considering it has a long list of genetic risk factors, why should MND be any different? Research taking steps in this direction is therefore long overdue. One such step was published in Gene Therapy and is titled Healthy and diseased corticospinal motor neurons are selectively transduced upon direct AAV2-2 injection into the motor cortex.The authors report that they successfully transduced motor nerves of mice models of MND. In doing so they have set the stage for gene therapy in MND. I don’t claim to understand it all, but it sounds very much like they have set the ball rolling. Promising.