Thursday, May 29, 2008
To my dozens of loyal readers out there, I should let you know that I'll not be posting for the next month. William Butler Yeats said that a fulfilled life is one in which there is "a continuous drinking of knowledge". I hate to interrupt the imbibing; but I promise to return with a tall glass of neuropathology on June 30, 2008. In the meantime, may your hippocampi continue to be stimulated elsewhere!
Tuesday, May 27, 2008
“Limb-girdle muscular dystrophy and Miyoshi Myopathy are general clinical designations that are given depending on the initial pattern of muscle weakness seen in patients. LGMD is characterized by proximal muscle weakness, while Miyoshi Myopathy is characterized by distal muscle weakness.
“There are 19 genetically defined forms of LGMD (6 dominant and 13 recessive). Clinically, many of the LGMDs are similar and the exact form can only be identified by protein screening or the identification of mutations. For LGMD2B, the “2” signifies the recessive nature of the disease and the “B” indicates that the LGMD is caused by a problem with the dysferlin protein.
“Miyoshi Myopathy is also a genetically heterogeneous form of muscular dystrophy with 3 different linked loci identified to date. At present, mutations in only one gene have been identified that are known to result in Miyoshi Myopathy. That gene, like LGMD2B, is dysferlin.
“Therefore, LGMD2B and Miyoshi Myopathy (caused by mutations in dysferlin) are allelic disorders. The initial clinical presentation (i.e. pattern of muscle weakness) of LGMD2B and Miyoshi Myopathy are very distinct. However as the disease progresses, the majority of patients begin to show a mixture of both distal and proximal weakness. Some patients even initially present with a mixture of both proximal and distal muscle weakness. There are even some reports of both an LGMD2B and Miyoshi Myopathy presentation occurring in siblings within the same family with the same genetic mutations.
“Therefore from my perspective as a geneticist, LGMD2B and Miyoshi Myopathy (resulting from mutations in dysferlin) are the same disease and the variations in clinical presentation are the result of other modifiers (genetic or environmental) that have yet to be identified. Given this fact both LGMD2B and Miyoshi Myopathy could be treated with the same genetic therapeutic approaches (i.e. gene therapy, exon skipping, etc). This is why we include both types of patients in our patient registry."
Friday, May 23, 2008
Thursday, May 22, 2008
Wednesday, May 21, 2008
Monday, May 19, 2008
However, I posed Neil’s question to Dr. George R. Leichnetz, neuroanatomist at Virginia Commonwealth University and author of Digital Neuroanatomy: An Interactive CD Atlas with Text (Wiley-Liss, 2006). Here is Dr Leichnetz’s emailed response to my query:
“The "interthalamic adhesion" or "massa intermedia" is (as its name implies) an adherence of the ependymal lining of the midline third ventricle. Importantly, it is not a commissure, ie. there are no inter-thalamic fibers exchanged between the two thalami. In subhuman primates and other mammals there is a true midline commissure through which fibers are exchanged. But in man the functions of the two cerebral hemispheres are specialized and separate, hence, their principal source of afferents, the thalamus, are separate. It would be functionally disadvantagious if there were a commissure at the level of the thalamus. So, the absence of this adhesion has no negative functional consequence as far as I know.”
The next time I do a brain autopsy, I’ll take a microscopic section of the interthalamic adhesion and post a photomicrograph to prove Dr. Leichnetz’ point. Given Dr. Leichnetz’ comments, it would be highly unlikely that the presence of an interthalamic adhesion would have anything directly to do with intelligence -- or anything else, for that matter!
Friday, May 16, 2008
Tuesday, May 13, 2008
The first thing most of us think of when a patient presents with rapidly progressive dementia (RPD) is Creutzfeld-Jakob disease (CJD). But not so fast! Michael Geschwind, with Aissa Haman and Bruce Miller, of the
Friday, May 9, 2008
Thursday, May 8, 2008
The best neuropathologyblog post in January of 2008 presented frozen section room rules as described by Dr. Mark Cohen of Case Western in his seminar called "Neuropath@Nite – Staying Cool in the Frozen Room”. The seminar, presented at the annual College of American Pathologists meeting in October of 2007, was conducted in collaboration with Dr. Joe Parisi of the Mayo Clinic.
Here are Frozen Room Rules to live by:
1. You, and you alone, know if you need more tissue to make an intraoperative diagnosis.
2. When misdiagnosing a lesion, always strive to do the least amount of harm!
3. Lipid-laden macrophages are very strong evidence against the presence of a glioma.
4. Rule number 2 trumps rule number 3 (explained as: “It is easier to reoperate on a patient with a glioma initially misdiagnosed as a tumor-like demyelinating lesion, than replace resected demyelinated tissue initially misdiagnosed as gliomas.”)
Tuesday, May 6, 2008
Thursday, May 1, 2008
From what disease did "the Elephant Man" suffer?
Joseph Merrick was originally thought to be suffering from neurofibromatosis type I, a genetic disorder also known as von Recklinghausen's disease. However, it was postulated in 1986 that Merrick actually suffered from Proteus syndrome (a condition which had been identified by Michael Cohen seven years earlier). Unlike neurofibromatosis, Proteus syndrome (named for the shape-shifting god Proteus) affects tissue other than nerves, and is a sporadic rather than familially transmitted disorder. In July 2003, Dr. Charis Eng announced that as a result of DNA tests on samples of Merrick's hair and bone, she had determined that Merrick certainly suffered Proteus syndrome, and may have had neurofibromatosis type I as well. (The above information is adapted from the wikipedia article. But citations are provided.)
The clinical manifestations of Proteus syndrome are, as the name implies, protean. They include: partial gigantism of hands or feet; hemihypertrophy; subcutaneous lipomas; multiple nevi; areas of thickened skin and subcutaneous tissue; macrocephaly; skull anomalies; and accelerated growth in long bones. Mentation can be normal or retarded.
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