Arteriovenous micromalformation of the trigeminal root: intraoperative diagnosis with indocyanine green videoangiography: case report.

BACKGROUND AND IMPORTANCE

To report on a single case of arteriovenous micromalformation (micro-AVM) of the trigeminal root that was diagnosed during microvascular decompression for trigeminal neuralgia with the use of indocyanine green (ICG) videoangiography.

CLINICAL PRESENTATION

A 52-year-old woman with drug-resistant trigeminal neuralgia underwent a key hole suboccipital cerebellopontine angle exploration after the usual magnetic resonance imaging (MRI) screening had raised the suspicion of a vascular compression. In surgery, the petrosal vein was found to be bigger than usual and arterialized; the trigeminal root was embedded in a tangle of abnormal arterialized vessels. Intraoperative ICG videoangiography showed that the direction of flow in the arterialized petrosal vein was anterograde, thus allowing for the differential diagnosis between micro-AVM and tentorial dural fistula. It was possible to achieve only a partial nerve decompression because of the intimate relationship between the trigeminal root and the pathological vessels. Postoperative angiography and MRI with contrast administration confirmed the intraoperative diagnosis of micro-AVM. The patient was discharged neurologically intact on postoperative day 4. One month after surgery, she remains pain-free despite a 50% reduction in antiepileptic drugs.

CONCLUSION

Surgeons performing microvascular decompression should be aware that a diagnosis of vascular compression based on MRI without contrast administration could not exclude the presence of a pontine micro-AVM. ICG videoangiography provides an elegant means of showing the flow dynamics of these pathological vessels. An MRI protocol that is suitable to avoid this kind of intraoperative drawback should be defined and systematically used in the preoperative evaluation of all such surgical candidates.