Friday, August 29, 2008

What's is meant by "luysian" in dentatorubral-pallidoluysian atrophy?

Dentatorubral-pallidoluysian atrophy is an autosomal dominant spinocerebellar ataxia which occurs most frequently among the Japanese. "Dentato" refers to the dentate nucleus of the cerebellum; and "rubral" alludes to the red nucleus. "Pallido" of course indicates the globus pallidus. But what does "luysian" refer to? I posed this question to the illustrious Dr. John Donahue (pictured), neuroanatomist extraordinaire, who reminded me that the subthalamic nucleus is also knows as the "Body of Luys" or "Corpus Luysii", named in honor of the noted French neurologist Jules Bernard Luys (1828–1897), who gave the first detailed description of this structure in the basal ganglia.

Wednesday, August 27, 2008

Neuropathology Blog initiates new feature

On more than one occasion, I have been discussing something with a colleague and remembered that I had blogged about that very same issue some months previously. Then, in order to find the post, I would have to try to remember when I posted on the subject if I wanted to find the entry in the archives. That was fine back when I had only twenty or thirty posts on this site. Now, I have more than one hundred posts; and finding old posts has become tedious. Not to worry. The people at blogger provide a feature called "labels" which allows me to attach search terms to each of my posts. I have renamed the feature "tags", as it sounds more appropriate to me. From now on, you will see along the right-hand column of the page a list of tags, with the number of posts tagged with a particular subject heading. I know this will make searching the archive much easier. It will take about a week for me to go through each post on the site and make tags for each, but it will eventually make searching this blog a whole lot easier.

Monday, August 25, 2008

If the brain were a hard disk

According to Prof. Jeff Lichtman (pictured) of Harvard's Center for Brain Science, the data storage capacity of the human brain is 1 million petabytes. A petabyte is equal to 1000 terabytes; and a terabyte is equal to 1000 gigabytes. In other words, the human brain has storage equivalent to 1000 billion gigabytes of information. So, why can't I remember where I put my car keys?

Saturday, August 23, 2008

What are Remak cells?

Remak cells, named after Polish-born Robert Remak (1815-1865)(pictured), are Schwann cells which do not myelinate, but rather surround unmyelinated peripheral nerve fibers. According to Greenfield's Neuropathology (8th Edition), "unmyelinated axons are always of small diamter and pass through the nerve trunk in groups of 8-15 within a common chain of Schwann cells".

Tuesday, August 19, 2008

Central core disease

Central core disease is a congenital myopathy defined by the presence on muscle biopsy microscopy of numerous muscle fibers that lack oxidative activity, thus making "cores" on NADH-stained slides within muscle fibers. Reported to be one of the most frequent forms of congenital myopathy, this disease usually becomes apparent in infancy or childhood. Facial, neck, and proximal limb weakness with generalized hypotonia are the characteristic clinical features; but phenotypic severity is widely variable. The disease is linked to a ryanodine receptor gene mutation (RYR1, chromosome 19q13). The ryanodine receptor is depicted in the illustration. Malignant hyperthermia is highly associated with central core disease, independent of the degree of muscle weakness.

(Main source: Mark Cohen's chapter in Prayson's Neuropathology, A volume in the Foundations in Diagnostic Pathology series, first edition)

Friday, August 15, 2008

Estimated US brain cancer cases in 2008

The American Cancer Society recently put out a publication entitled Cancer Facts and Figures 2008 in which it is reported that there will be 21,810 new brain and other nervous system cancers in the United States in 2008. Compare that to the estimated number of new lung and bronchus cancers: 215,020.

Tuesday, August 12, 2008

A 48-year-old man with mental confusion

We had an interesting case here last week of a 48-year-old gentleman with a clinical diagnosis of exacerbation of "some kind of an autoimmune encephalitis". The clinicians were wondering about CNS vasculitis and multiple sclerosis but really didn't know what the cause of the patient's problem was. An MRI showed multifocal edema and infarcts. He had been receiving weekly steroids with some improvement, but was now getting more symptoms of encephalopathy (confusion, weakness, etc.). A brain biopsy was performed, which showed the small vessels stuffed with neoplastic B-cell lymphocytes. The diagnosis based on brain biopsy was intravascular (angiotrophic) large B-cell lymphoma, a rare lymphoma wherein the neoplastic cells lack the capacity for diapedesis, remaining captured within the vascular lumen (pictured) and causing secondary brain infarction.

Friday, August 8, 2008

Loss of von Economo neurons may be associated with frontotemporal dementia

On Wednesday, I wrote about the fact that the brains of gorillas weigh only about 40% as much as human brains. There is, however, one way in which our brains are similar to simians: the presence of the von Economo neuron (VEN).

Constantin von Economo demonstrated in the 1920’s that these neurons are present only in the anterior cingulate and insular cortices (layer Vb). It was later determined that VENs are only present in hominids (humans and great apes), and that they are more numerous on the right side of the brain. Also referred to as spindle neurons because of their spindle-shaped cell bodies, VENs are larger than pyramidal neurons and tend to cluster parallel to small arterioles (pictured on right as compared to pyramidal neuron). More recently, it was found that VENs are also present in various species of whales and in elephants. The common theme here is that VENs are present in social animals with large brains. Since the VEN-populated areas of the brain are preferentially affected in frontotemporal dementia (FTD), it is thought that perhaps loss of these neurons may be related to the aberrant social functioning seen in FTD patients.

Breaking News: Neuropathologist Kevin Roth named UAB pathology chair

I just heard that Kevin Roth, MD, director of neuropathology at the University of Alabama, has been named chair of the UAB Department of Pathology. Congratulations, Dr. Roth!

Wednesday, August 6, 2008

Brain Factoid

"The average adult brain weight of a human is 1300-1400 g; an adult gorilla's brain weighs only 500 g."

- From Dan Brat's introductory chapter in Prayson's Neuropathology (2005). By the way, it is rumored that Prayson has agreed with the publisher (Elsevier) to come out with a second edition of this book, perhaps sometime in 2010.

Monday, August 4, 2008

Robert Novak to quit his job because brain tumor prognosis is "dire"

I just heard on National Public Radio that conservative columnist Robert Novak, about whom I wrote last week when it was announced that he had a brain tumor, will no longer be working for the Chicago Sun-Times. When you hear the word "dire" on a news story in connection to a brain tumor, you have to think that they're talking about a glioblastoma multiforme. That's probably the diagnosis for Senator Ted Kennedy's tumor as well.

Friday, August 1, 2008

Best Post of April '08: Neuropathologists meet in San Diego

And now for another in my occasional “Best of the Month” series, where I march through the past months choosing only the very best blog posts. This one, which features the illustrious Dr. Mark Cohen (pictured) is from Thursday, April 10, 2008:

The esteemed and illustrious Dr. John Donahue attended the recent American Association of Neuropathologists annual meeting in San Diego. He was kind enough to provide a summary of the famous Diagnostic Slide Session from that meeting as follows:

“It came time for the Diagnostic Slide Session, now being moderated by Anthony Yachnis. It can be summed up as follows: "Dr. Mark Cohen, ROCK STAR!!!" He had to get at least 7/10 cases absolutely correct. He was diagnosing things I had never even heard of. There was a case of "vanishing white matter disease," also called "childhood ataxia with central hypomyelination" and "ovarian leukodystrophy," due to a mutation in eukaryotic initiation factor 2B, and he nailed it! I have never even remotely heard of that disease. There was also a case of intractable epilepsy due to "filamin A" (on chromosome X) astrocytic inclusions that look superficially like Rosenthal fibers, and he nailed it! I never heard of that, either. It was one of the most impressive diagnostic exhibitions I have ever seen. I asked him how long he's been doing this; he said 15 years or so. The cases were so hard that I only felt comfortable going up to the mic once, and after I gave my differential diagnosis, the speaker said "What did you do with the unstained slide that I provided?" I said, "I didn't want to waste it, so I was waiting to see the right answer." That generated laughter and applause!”

Thanks for your contribution, Dr. Donahue. And congratulations are in order. It turns out that an image from Dr. Donahue’s article Apolipoprotein E, Amyloid-[beta], and Blood-Brain Barrier Permeability in Alzheimer Disease appears on the cover of the current issue of the Journal of Neuropathology and Experimental Neurology.

Next week, I’ll be posting from the annual meeting of the American Academy of Neurology in Chicago, IL. The meeting celebrates the 60th anniversary of the organization. The first annual meeting, featuring 38 presented papers, was held at the French Lick Springs Hotel in 1949. Two thousand abstracts have been accepted for this year’s meeting.