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| zoe and abi
- Fri Nov 13, 2009 6:03 pm
My Mum has just received the results from an MRI and they state "angioma, cavernous. The doctor that she saw was not very helpful and none of our questions were answered. Some of the other key words used are "medulla" "intra-axial lesion" and "hemorrhagic infract". I have tried to research this and to be honest I am getting very confused. Could you please shed some light on this for me?
| Dr.M.Aroon kamath
- Mon Dec 21, 2009 10:43 am
Cavernous hemangiomas are congenital, developmental malformations of the vascular bed (There is a bit of controversy as to whether these are true vascular malformations or very slow growing tumors of capillaries).
In the Central nervous system (CNS), 'intra-axial' indicates that a lesion is 'within' the CNS and 'extra-axial' indicates outside of the CNS.
'Endophytic' refers to 'growing inwards'. 'Exophytic' refers to 'growing outwards'.Due to the high concentration of axons in brainstem,
the symptoms due to tumors in this location
can appear before these become detectable by neuroradiology. Patients often present with pyramidal-tract symptoms,cranial nerve dysfunction, or cerebellar symptoms.They can bleed and cause infarction, thus producing symptoms.
Lesions in the brain-stem (mid-brain, pons and medulla oblangata) were not so long ago were considered beyond the scope of surgery and used to be irradiated. The reason behind this were as follows....
- the relatively small cross-sectional area that is tightly packed with nerve fibers getting into and out of the cerebral hemispheres and the cerebellum made surgery extremely hazardous,
- difficulties in obtaining sufficiently large specimens for adequately categorizing by histopathology,
- lack of imaging techniques such as CT and MRI(neuroradiology).
From 1980 onwards important advances in the field of neuroradiology, neurophysiology and neurosurgical techniques made it possible to attempt to classify these tumors based on CT and MRI findings. Perfusion and diffusion MR is becoming a more and more important tool.
The main purpose of these classifications was to identify which of the tumors would be amenable to surgical extirpation.
Image guided stereotactic biopsies became possible.
The use of intra-operative neurophysiologic monitoring (sensory
and evoked potentials) provides real-time information
about the integrity of brain-stem throughout the
surgical procedure. Modern devices such as surgical microscopy, microsurgery (including 'neuronavigator-guided' surgery), bipolar bayonet forceps, contact laser (Nd-YAG) and ultrasonic aspirator(CUSA) greatly contributed to refinements in the surgical techniques.
On T2-weighted MRI, the combination of a reticulated core of mixed signal intensity (SI) with a surrounding rim of decreased SI strongly suggests the diagnosis of a cavernous malformation. Smaller lesions appear as (black dots)- areas of decreased SI. The sensitivity of MRI is based on magnetic susceptibility and possibly diffusion effects produed by the presence of excessive iron (hemosiderin).
Unlike the more common 'Gliomas', Cavernous hemangiomas produce what is called as the 'parenchymal window' , which is the most important parameter to plan the choice of surgical approach. "Safe entry zones" may be identified following modern imaging of the surgical anatomy of the brain stem.