Saturday 1 December 2012

Pseudomeningocele with Nerve root Avulsion on MRI

A middle aged male with history of trauma due to a motor vehicle accident. 
Now complaints of Right arm weakness and parasthesias. A “frostbite” sensation which progressed to a sharp right shoulder and neck pain with a burning sensation.
There is typical history of impact caused his head to flex on left, to the contralateral side. 
MRI Sag T2 right ward section
Coronal FIESTA
MRI Sag T2 right far lateral section for end on view of neural foramen show abnormal T2 hyper intensity in the region of neural foramen at C6-7 and C7-D1 level with non visualization of normal punctate iso intense dots of nerve roots. Cystic outpouching noted iso intense to Csf along the course of corresponding right sided exiting nerve roots on Coronal FIESTA can be attributed to pseuomeningoceles. Redundant nerve roots noted just at the top of these pseudo meningoceles implies to an associated Nerve root avulsion. 

Diagnosis: Traumatic Pseudomeningocele with Nerve root avulsion. 

Pseudomeningoceles represent a tear in the meningeal sheath that surrounds the nerve roots and extravasation of CSF into the neighboring tissues. Because they are filled with fluid, they are easily identifiable on T2-weighted MR images and MR Myelography, does not require any intra thecal contrast.
MR can adequately demonstrate the traumatic pseudomeningoceles however myelography and CT myelography remain the gold standard. In another recent study, neurosurgeons when asked which method they prefer and use to evaluate the avulsed brachial plexus before surgery. Eighty percent prefer post myelography CT, 20% prefer MRI, and 41% use both methods, whereas the remaining participants expressed no preference. As per Volle et al. the sensitivities of cervical myelography, CT myelography and MR are 100%, 45% and 6% respectively, for demonstration of nerve root avulsions. Xray and CT myelography not only show the level of avulsion but also documented overall size and morphology of the associated pseudomeningocele. The difficulty with MR imaging is it can demonstrate pseudomeningocele as an indirect evidence of nerve root avulsion. But the fact is that Pseudo meningocele can occur without root avulsion and root avulsions may occur without pseudomeningoceles.
Recent advances in high resolution MR imaging with steady state sequences may allow evaluation of exiting nerve root avulsion. In infants, the use of MRI is recommended because post myelography CT is a minimally invasive procedure, needs contrast and radiation exposure. Adequate information can be provided by noninvasive MRI. MR myelography is helpful in depicting pseudomeningoceles in a fashion similar to conventional myelography, but it is a supplemental method because most of the lesions are identifiable on MRI.

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