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Thursday, March 22, 2007

Central Pontine Myelinolysis





Central pontine mylineolysis


I was given the request last night to scan this womans brain. She was a young lady with a history of alcohol abuse and seizures. I talked to her over the phone to make sure we could get a good medical history before the MRI scan. Her speech was very slurred and she told me she had difficulty swallowing. To my supprise she said she had been in the hospital for 2 weeks, with these symptoms for 3 weeks. I imediatelly thought she infarcted her pons becuase she had no physical weakness in her arms or legs. I figured possible lacunar infarct. To my suprise she was Diagnosed with Central Pontine Mylineolysis from the MRI scan by our Radiologist. This was the first time I had heard of this . I learn Something new everyday. The following is Information on the topic:

Adams et al described central pontine myelinolysis (CPM) as a unique clinical entity. They published their findings in 1958, observing that patients who suffered from alcoholism or malnutrition developed spastic quadriplegia, pseudobulbar palsy, and varying degrees of encephalopathy or coma from acute, noninflammatory demyelination that centered within the basis pontis.



physicians recognize that CPM occurs inconsistently as a complication of severe and prolonged hyponatremia, particularly when corrected too rapidly. Standard of care requires judicious treatment of electrolyte disturbances to reduce the incidence of osmotic myelinolysis.








abnormal normal



Central pontine myelinolysis is a neurologic disease caused by severe damage of the myelin sheath of nerve cells in the brainstem, more precisely in the area termed the pons. The most common cause is the rapid correction of low blood sodium levels (hyponatremia). Some scholars postulate that the real cause might be the lack of a substance that is essential for brain activity and is lacking due to malnutrition. The fact that this condition is most frequently observed in patients with general ill health (alcoholism, cachexia etc.) is in accordance with this assumption. Imaging by MRI demonstrates an area of high signal return on T2 weighted images. Frequently observed symptoms in this disorder are weakness, double vision and loss of consciousness. To avoid myelinolysis, the correction of hyponatremia should not exceed 1 mEq/L per hour.



The rapid rise in sodium concentration is accompanied by the movement of small molecules and pulls water from brain cells. Through a mechanism that is only partly understood, the shift in water and brain molecules leads to the destruction of myelin, a substance that surrounds and protects nerve fibers. Nerve cells (neurons) can also be damaged. Certain areas of the brain are particularly susceptible to myelinolysis, especially the part of the brainstem called the pons. Some individuals will also have damage in other areas of the brain, which is called extrapontine myelinolysis (EPM). Experts estimate that 10 percent of those with CPM will also have areas of EPM.





The ideal treatment for myelinolysis is to prevent the disorder by identifying individuals at risk and following careful guidelines for evaluation and correction of hyponatremia. These guidelines aim to safely restore the serum sodium level, while protecting the brain. For those who have hyponatremia for at least 2 days, or for whom the duration is not known, the rate of rise in the serum sodium concentration should be kept below 10 mmol/L during any 24-hour period, if possible



The prognosis for myelinolysis is variable. Some individuals die and others recover completely. Although the disorder was originally considered to have a mortality rate of 50 percent or more, improved imaging techniques and early diagnosis have led to a better prognosis for many people. Most individuals improve gradually, but still continue to have challenges with speech, walking, emotional ups and downs, and forgetfulness.
What research is being done? (source NINDS)



This syndrome is characterized by a gradual neurologic deterioration developing one to several days after complete or partial correction of chronic hyponatremia. Neurologic deterioration may often be preceded by a transient improvement paralling the correction of electrolyte disturbance. Fluctuating levels of conciousness, convulsions, hypoventilation or hypotension may herald the onset of this syndrome. Eventually pseudobulbar palsy and quariparesis develops. Swallowing dysfunction (often with episodes of aspiration) and inability to speak may be dominant features. In severe cases, the patient may develop a "locked-in syndrome" - they are awake but unable to move or communicate. Marked improvement may occur presumably because of reyelination. Although various imaging modalities may be confirmatory, positive diagnostic tests are not essential to diagnose the osmotic demyelination syndrome. If psedubulbar palsy and limb paralysis gradually develop after hyponatremia is corrected, the clinician should strongly suspect a demelinating lesion of the pons. (source)




MRI IMAGING of Potine Myelinolysis

Thursday, March 08, 2007

MS of the nervous system

Multiple sclerosis (MS) is one of the most common diseases of the central nervous system. Today over 2,500,000 people around the world have MS.MS is the result of damage to myelin - a protective sheath surrounding nerve fibres of the central nervous system. When myelin is damaged, this interferes with messages between the brain and other parts of the bodySymptoms vary widely and include blurred vision, weak limbs, tingling sensations, unsteadiness and fatigue. For some people, MS is characterised by periods of relapse and remission while for others it has a progressive pattern. For everyone, it makes life unpredictable.
Source





Research has been difficult to do on patients with MS for many reasons. One reason is the area is often inaccessible because MS occurs is the Brain and Cervical spinal cord. Antoher important reason is that every patient disease does not follow the same pattern of progression. This is why comparing patients can be so difficult. MS is also very unpredictable, which makes it hard to treat. Patients may not be showing symptoms but may have underlying disease process . There are four types of MS, (see chart)








Relapsing-Remitting MS
In this form of MS there are unpredictable relapses (exacerbations, attacks) during which new symptoms appear or existing symptoms become more severe. This can last for varying periods (days or months) and there is partial or total remission (recovery). The disease may be inactive for months or years.
Frequency - approx 25%

Benign MS
After one or two attacks with complete recovery, this form of MS does not worsen with time and there is no permanent disability. Benign MS can only be identified when there is minimal disability 10-15 years after onset and initially would have been categorised as relapsing-remitting MS. Benign MS tends to be associated with less severe symptoms at onset (e.g. sensory).
Frequency - approx 20%

Secondary Progressive MS
For some individuals who initially have relapsing-remitting MS, there is the development of progressive disability later in the course of the disease often with superimposed relapses.
Frequency - approx 40%

Primary Progressive MS
This form of MS is characterised by a lack of distinct attacks, but with slow onset and steadily worsening symptoms. There is an accumulation of deficits and disability which may level off at some point or continue over months and years.
Frequency - approx 15%
(Source)

Diagnosis

MRI imaging has come a long way in being able to detect small lesions in the brain and spinal cord. The most useful sequences in MRI scanning are Flair Sagitals and Axials. Lesions on T2 axial scans of the brain are hyperintense an hypointense on T1 weighted images.



Hypointense Lesions on T1-Weighted Images A subset of T2 hyperintense lesions in the brain may also show hypointensity on corresponding T1-weighted scans.At the time of the acute appearance of new T1 hypointense lesions, almost half of these represent areas of reversible edema, inflammation, and demyelination
and will return to isointensity over the next several months. However, chronic lesions that persist over several months likely represent irreversible and profound
tissue damage due to demyelination and axonal loss. Brain hypointense T1-weighted lesions have correlated better with disability than have lesions on T2-weighted images in some but not all studies.



Gd-enhancing lesions are correlated histopathologically with T cell migration across the blood-brain barrier and are indicative of active inflammation.These lesions are
more sensitive to disease activity than clinical relapses. Moreover, the appearance of Gd-enhancing lesions predicts future relapses but not long-term disability.Gdenhancing lesions, which may appear as homogeneous, heterogeneous, tumor-like, and ring enhanced, are more commonly seen in patients with relapsing-remitting MS (RRMS) than in patients with progressive forms of the disease.
The open-ring pattern is particularly characteristic
of MS lesions.




(Rohit Bakshi, MD, FAAN)

Cutting Edge MRI

Diffusion tensor weighted mri imaging and ms






Treatment

There is no known definitive cure for multiple sclerosis. However, several types of therapy have proven to be helpful. Different therapies are used for patients experiencing acute attacks, for patients who have the relapsing-remitting subtype, for patients who have the progressive subtypes, for patients without a diagnosis of MS who have a demyelinating event, and for managing the various consequences of MS attacks. Treatment is aimed at returning function after an attack, preventing new attacks, and preventing disability.
Various disease-modifying treatments have been approved by the USA's Food and Drug Administration (FDA) for multiple sclerosis.
INTERFERONs:
These are medications derived from human cytokines which help regulate the immune system. Betaseron has been approved by the FDA for relapsing forms of secondary progressive MS.
Interferon beta-1a: (trade names Avonex and Rebif)
beta-1b: (trade name Betaseron [in Europe and Japan Betaferon]).
GLATIRAMER ACETATE: (trade name Copaxone)
A synthetic medication made of four amino acids that are found in myelin. This drug stimulates T cells in the body's immune system to change from harmful, pro-inflammatory agents to beneficial, anti-inflammatory agents that work to reduce inflammation at lesion sites.
MITOXANTRONE: (trade name Novantrone)
This medication is effective, but is limited by cardiac toxicity. Novantrone has been approved by the FDA for secondary progressive, progressive-relapsing, and worsening relapsing-remitting MS.
NATALIZUMAB: (trade name Tysabri).
This medication is effective and safe alone but in combination with other immunotherapies can lead to PML.
Relapsing-remitting symptomatic attacks can be treated. Patients in the United States are typically given high doses of intravenous corticosteroids, such as methylprednisolone, to end the attack sooner and leave fewer lasting deficits. Patients' self-reporting indicates that many find benefit from a number of other medicines.[3]
Currently there are no approved treatments for primary progressive multiple sclerosis, though several medications are being studied and are described at Therapies for multiple sclerosis.
source

Sunday, March 04, 2007

Single-Molecule Magnet Fe8 for MRI Contrast Agent.

Published: 14 February 2007 11:50 AM
Industry Channel: Medical & Pharmaceutical
Source: The Engineer Online

A Florida State University researcher has collaborated in a research project that could lead to ways of producing even sharper magnetic resonance imaging (MRI) images.


Naresh Dalal, the Dirac Professor of Chemistry and Biochemistry at FSU, recently conducted experiments with other researchers from FSU, the University of Colorado and the National Institute of Standards and Technology that uncovered unique properties in a molecular magnet, properties that could significantly increase the resolution of MRIs. Their paper, ‘Efficacy of the Single-Molecule Magnet Fe8 for Magnetic Resonance Imaging Contrast Agent Over a Broad Range of Concentration,’ was published in the current issue of Polyhedron.


‘There are continual efforts to enhance the level of image clarity found in today's MRI devices,’ Dalal said. ‘MRIs utilise injectable dyes, but those in current use, while easy to manufacture, offer a relatively low contrast. Our experiments show that a class of materials known as single-molecule magnets might produce greater contrast in medical imaging, meaning MRIs would be much more accurate.’


Working at FSU and the National High Magnetic Field Laboratory, Dalal and another FSU researcher, chemistry graduate teaching assistant Vasanth Ramachandran, were able to synthesise a substance known as Fe8 that is one of the strongest magnets known.


‘Fe8 is a molecule made up of eight iron ions that form a tight molecular bond,’ Dalal said. ‘It has a powerful magnetic field, which is obviously important in generating a very clear image with an MRI device. What's more, Fe8 is non-toxic and water-soluble, making it safe for injection into the body.’


Molecular magnets such as Fe8 hold great potential for other applications as well, he said.


‘Computer memories and other high-tech storage devices utilise magnetic compounds,’ Dalal said. ‘Consider the compact disc. Using current technologies, the magnetic coating on a disc's surface is about one micron in depth. But if a CD instead was coated with Fe8, the Fe8 film would be only about a nanometre. This could increase our ability to store data in smaller and smaller spaces.’ It also could lead to significant breakthroughs in the area of quantum computing, which has the potential to create computers that are exponentially faster and more powerful than the ones in use today, he said.


Despite the promising results suggested by the team's research, Dalal admitted that there still are some hurdles to overcome before Fe8 becomes a viable MRI option.


‘These compounds are not very stable,’ he said. ‘They break down in water within a few hours. We're now looking at ways to increase their stability so that they can be stored for long periods of time and transported easily.’


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