Microvascular decompression of the optic chiasm

Case report

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Elongation of the anterior cerebral artery (ACA) and subsequent compression of the chiasm rarely have been reported as causes of a visual field deficit. Neither has microvascular decompression of the chiasm been described in this circumstance. The authors report on a case of progressive visual deficits caused by compression of the optic apparatus by a right elongated ACA as documented on MR imaging. Microvascular decompression was proposed as treatment. The right A1 segment was larger than usual and tortuous, transmitting its pulsations into the chiasm. A piece of Teflon was inserted between the A1 segment and the chiasm. Following surgery, the visual field deficit progressively improved. At 4 months after surgery, the patient's visual fields were normal. Therefore, an elongated ACA can compress the chiasm and result in a visual field deficit. In such circumstances when facing a progressive visual field deficit, microvascular decompression may improve vision.

Abbreviations used in this paper: ACA = anterior cerebral artery; ICA = internal carotid artery; MVD = microvascular decompression.

Article Information

Address correspondence to: Michel W. Bojanowski, M.D., F.R.C.S.C., Neurosurgery Division, CHUM-Hôpital Notre-Dame, 1560 Sherbrooke Street East, Montreal, Quebec, Canada H2L 4M1. email: michel.bojanowski.chum@ssss.gouv.qc.ca.

Please include this information when citing this paper: published online October 23, 2009; DOI: 10.3171/2009.9.JNS081658.

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Cerebral MR images (left and right) revealing a right proximal ACA vascular loop compressing the optic chiasm and displacing it inferiorly.

  • View in gallery

    Intraoperative photographs showing an indentation (A, asterisk) made in the chiasm by the elongated right ACA and a piece of Teflon (B) inserted between the right tortuous A1 segment and the chiasm.

  • View in gallery

    Preoperative visual field assessments (upper) documenting the progression of binasal visual field deficits as well as postoperative analyses (lower) revealing normalization of the visual field defects.



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