Larry in southern California (whose wife has PSP) emailed several of the Yahoo!Groups yesterday about this August ’07 Irene Litvan article, asking if anyone knew anything about “transcranial sonography (TCS),” which is a diagnostic method mentioned in the article. Turns out that only a short paragraph of the Litvan article was on TCS. Dr. Irene Litvan is one of the top experts in the world on PSP. She’s written quite a bit on CBD and MSA as well.
This review article is an update for neurologists as to what advancements have been made in the area of diagnostic tools, genetics, and treatments for PSP, CBD, and MSA. The rest of this post is a summary of what I learned from the article. If you want more details, read the abstracts of the articles on PubMed (pubmed.gov – enter in the ID#). (A few of the full articles are available online for free. It’s mostly the harder-to-comprehend papers that are free!)
Dr. Litvan, writing in August ’07, concludes the article by saying that the field of atypical Parkinsonian disorders — diagnostic tools, genetics, and treatment — has “significantly advanced over the past year.” From a patient/family perspective, it is hard to agree with her.
DIAGNOSIS. From the article, I learned about recent studies of four diagnostic methods using “ancillary tools”:
1. TCS (transcranial sonography): TCS may help distinguish PD vs. atypicals, PD vs. MSA/PSP, MSA/PSP vs. CBD, and perhaps PSP vs. CBD, if I’m reading this correctly. PSP can be differentiated from CBD because the dilation of the third ventricule of the brain has so far only been described in PSP. This TCS study was done in Europe. TCS cannot be performed in up to 20% of patients. The study had nothing to say about LBD or about differentiating MSA from PSP. Of all the papers referenced in her review article, this is the only one labeled as “of outstanding interest” by Dr. Litvan. (PubMed ID#17189043)
2. Diffusion-weighted MRI: This method may help distinguish PSP and MSA-P. (PubMed ID#17089396)
3. T2-weighted MRI: This method may help differentiate MSA and PD. (PubMed ID#17361340)
4. Saccade tasks: This sort of diagnostic test (of saccade latencies and directional errors) would be performed by a neuro-ophthalmologist. This test may help distinguish PSP vs. CBD/PD. (PubMed ID#17124191)
GENETICS. From the article, I learned some things about genetics that I was unaware of:
* The location of a second genetic risk for PSP was identified in 2007. (This utilized brain tissue at the Mayo Jax PSP Brain Bank. PubMed ID#17357082; very challenging reading)
* The LRRK2 genetic mutation, which can be a factor in PD and DLB, is “not associated with MSA or with sporadic PSP.” (This is the genetic mutation that was discussed in the Frontline program last week on PD, “My Father, My Brother, and Me.”)
TREATMENT. And here’s what I learned about treatment:
* Because of the success (“significant gait and postural balance benefits”) of an Italian study of DBS in two locations of the brain in advanced PD patients, Dr. Litvan believes that DBS of the pedunculopontine nucleus (PPN) “may be useful in treating the balance and gait disorder in the atypical parkinsonian disorders, particularly in patients with PSP and MSA.” In fact, CurePSP is funding a study of DBS of the PPN in those with PSP in Toronto. (PubMed ID#17251240)
* Mayo Rochester is studying respiratory dysfunction in MSA. (PubMed ID#17235127; very challenging reading)
* Transgenic mice models are being developed for PSP, CBD, and MSA.
What follows are the abstract of the article.
Robin
Current Opinion in Neurology. 2007 Aug;20(4):434-7.
Update of atypical Parkinsonian disorders.
Litvan I.
Department of Neurology, University of Louisville, Louisville, Kentucky.
PURPOSE OF REVIEW: This timely update discusses novel diagnostic approaches, recently identified genes, and innovative experimental symptomatic treatments for these devastating disorders.
RECENT FINDINGS: Differential patterns in the basal ganglia transcranial sonography, magnetic resonance diffusion-weighted imaging regional apparent diffusion coefficients in the brainstem, basal ganglia T2-weighted gradient echo sequences combined with fluid attenuated inversion recovery, or saccades error rates in single and mixed-task blocks could help differentiate the various parkinsonian disorders. In addition to the familial tauopathies (frontotemporal dementia associated with chromosome 17) presenting with an atypical parkinsonian phenotype, ‘TDP-43opathies’ and ‘tataboxbinding or ataxinopathies’, depending on the protein deposited in the brain, widen the scope of the familial atypical parkinsonian disorders. Recent identification of novel deep brain stimulation targets such as the pedunculopontine nucleus may help treat the balance and gait disorder in atypical parkinsonian disorders in the near future.
SUMMARY: These new findings are important for diagnosis, help better understanding of the nosology of these disorders, and will likely in the near future impact our clinical practice.
PubMed ID#: 17620879 (see pubmed.gov for abstract only)