Tags: spinocerebellar ataxia

It's World RARE Disease Day! 2015 #RareDiseaseDay2015

What is a Rare Disease?

In the U.S., any disease affecting fewer than 200,000 people is considered rare. This definition comes from the Orphan Drug Act of 1983 and is slightly different from the definition used in Europe. There are nearly 7,000 rare diseases affecting nearly 30 million Americans. In other words, almost one in ten Americans are suffering from rare diseases.

Besides dealing with their specific medical problems, people with rare diseases struggle to get a proper diagnosis, find information, and get treatment. The rarity of their conditions makes medical research more difficult.

Oh yeah…this is every year on the last day of February…not just Leap Year’s! Perhaps I should shift my advocacy focus to something along these lines, since I have been diagnosed with two rare disease, since I blogged about “RARE Disease Day 2012″.

First is Narcolepsy, which I’ve had symptoms that could be argued trace back to late Elementary/Early High School (which got missed, since teachers were on strike for most of that year.) Though didn’t really become a significant problem to me, personally, until sometime during Freshman year at University (where, I had come across a clipping that there were pockets of H1N1 cases reported for the ‘86/’87 flu season.)

I received my second/current diagnosis of Narcolepsy in July 2012.

The first one in 2011 was based on Neurologist re-review of MSLT, but then he reversed his diagnosis for Narcolepsy on the basis that my Cataplexy wasn’t of the severe kind, and by spinal tap.

DSM-5 says narcolepsy is periods of an irresistible desire to sleep, or to fall asleep or nap with the same day, regardless of appropriateness of time or place. occuring at least 3 times per week over the past 3 months, accompanied by at least one of the following: Adult Cataplexy, Childhood Cataplexy, CSF Hypocretin <= 110 pg/mL, 4. PSG/MSLT finding.

ICSD-3 defines narcolepy type 1 as daily periods of irrepressible need to sleep or daytime lapses into sleep occurring for at least 3 months. With the presence of one or both of: Cataplexy and MSLT finding, or CSF hypocretin-1, of either up to 110 pg/mL or <1/3 of mean values obtained in normal subjects.

And narcolepsy type 2 as daily periods of irrepressible need to sleep or daytime lapses into sleep occurring for at least 3 months. And, requires 4 other tests, which are MSLT finding, no Cataplexy, no CSF Hypocretin-1 test or that the test result was > 110 pg/mL, and that the the first two can not be explained away by other causes.

Guess its a snap to never diagnose people with type 2, once you dismiss their reports of Cataplexy.

ICSD-3 also has a subtype of type 2 narcolepsy – due to a medical condition, such as PD, MS, head trauma.

Cataplexy is estimated to be present in ~70% of Narcolepsy cases, but I had heard that the severe form affects less than 10-15%. It is said that Narcolepsy with Cataplexy, “affects about one in every 3,000 Americans. More cases without Cataplexy are likely to exist.”

In the research for this post, I came across “Predictors of Hypocretin (Orexin) Deficiency in Narcolepsy with Cataplexy", where the thresholds are revealed to be from statistical analysis, using R. Where the optimal cutoff for CSF Hypocretin-1, the ROC curve analysis defines a gold standard of approximately 200 pg/mL as the cutoff for the diagnosis of Narcolepsy without Cataplexy vs those with, and is convenient with previously defined cut offs of low (<=110), intermediate (<=200), or normal (>200), where Narcolepsy with Cataplexy are those with 110 pg/ml or less. Intermediate….do we really exist? From what I recall reading (while I was required to lay as still as possible on back follow the spinal tap), those values were again through statistical analysis…putting the mean for Hypocretin levels for normals at ~399 pg/mL, and that 110 pg/mL was two standard deviations below the mean.

Also interesting, was “Survival curve analysis…no patient developed Cataplexy more than 26 years after onset of sleepiness, and that half (48%) with Hypocretin deficiency would eventually develop Cataplexy. When did my onset of sleepiness occur, and how does that correlate to where I had a Cataplexy episode in May 2012 that landed me in the ER (the outcome of that experience was a Dx of Cataplexy.)

And, then, I found “Complex movement disorders at disease onset in childhood narcolepsy with cataplexy", where ” The reported movements are not commonly described in adulthood Cataplexy that is typically characterized by jaw dropping, facial flickering or head dropping […], as well as by twitches of the face and of the limbs occurring during a Cataplectic spell and generally assessed by means of questionnaires” Hmmm…..

See: Narcolepsy Fact Sheet - NIH: NIINDS for more information.

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