- Examination of neurological system: Physical examination of the neurological system is needed to identify any focal sign or focal neurological deficit that can be attributed to the cavernous malformation as well as to document the preoperative status of the patient.
- Cutaneous examination: The skin should be examined for any cutaneous hemangiomas, which may suggest systemic cavernous malformation.
- Routine: No abnormal laboratory test results are expected.
- Angiography: DSA is needed if other vascular malformations are suspected, namely AVM. Venous drainage of the lesion and delayed capillary blush may be demonstrated (25, 36, 43, 51, 67).
- Acute setting – hemorrhage: Because CT scanning is easily and rapidly obtained, it is is usually the initial imaging for patients with acute onset of symptoms for detection of hemorrhage.
- Chronic setting – calcification possible: In nonacute cases, CT may demonstrate a focus of calcification.
- Both hematoma and calcification findings on CT are nonspecific.
MRI is the imaging of choice for diagnosis of cavernous malformations. SWI MRI and high-field MRI (7T or higher) may identify cavernous malformations or telangiectasias not detected by conventional sequences and low-field MRI (9). For surgical planning, DTI and fMRI can be useful to differentiate white matter tract and eloquent cortex from the lesion (9). Lesions seen on MRI can be classified on the basis of their appearance.
- Size variance with sequence: The appearance of cavernous malformations may vary from one MRI sequence to another. This size difference is the result of the varying magnetic susceptibility of blood products of different ages in one sequence type as compaed to another
- Hemosiderin: A peripheral ring of altered signal surrounding the cavernous malformation is characteristic for hemosiderin deposition and is due to repeated microhemorrhages. On T2-weighted and GRE MRI, areas of the brain containing hemosiderin-laden tissue give rise to a hypointensity that is larger than the actual size of the cavernous malformation. This feature is known as a blooming artifact, or blossoming.
- Associated DVA: The presence of a DVA in association with a cavernous malformation has several implications. Its presence supports the diagnosis of cavernous malformation. It is more likely that the cavernous malformation is a nongenetic, nonfamilial form of the disease. The presence of an associated DVA may influence surgical planning for removal of the cavernous malformation so as to avoid injury to the DVA and the consequence of venous ischemia.
- Capillary telangiectasias: Capillary telangiectasias have been described as areas of punctate enhancement seen in association with cavernous malformations on contrast-enhanced T1-weighted images. As opposed to cavernous malformations, they do not exhibit hemosiderin “blossoming” on T2-weighted and GRE sequences. They are most commonly reported in the pons as well as in the bed of DVAs (49).
Nuclear Medicine Tests
- Possible use in evaluation of seizures: Nuclear medicine tests are not required for the diagnosis of cavernous malformation. For working up the relationship between the lesion and epilepsy, ictal SPCT may be helpful.
- Seizure evaluation: EEG is needed as part of the investigation for epilepsy with underlying cavernous malformation.
- Optional for evaluation of cognitive function: Neuropsychological testing can be used to evaluate the development of cognitive function and correlate different locations of foci with the corresponding impact on cognitive function, such as the memory and speech function in relationship to a focus located in the temporal lobe.
Correlation of Tests
- Imaging, radionucleotide studies, EEG, and neuropsychological testing: CT and MRI are the key investigations for diagnosis. The results should be correlated with the patient’s clinical condition. If seizures are present, then lesions identified on imaging can be correlated with results of EEG, ictal SPCT, and neuropsychological tests.