Bony Tunnel Formation in the Middle Meningeal Groove: An Anatomic Study for Safer Pterional Craniotomy

Abstract

Objective: When the bone flap is removed in a pterional craniotomy, the middle meningeal artery (MMA) should be gently dissected to minimize blood loss. However, when the MMA pierces a bony tunnel in the middle meningeal groove it is easily damaged upon bone flap elevation. We have performed an anatomic study of this tunnel to render pterional craniotomy safer.

Methods: We examined 78 sides from 39 adult skulls for the presence and length of the tunnel, the distance between the lateral border of the superior orbital fissure and the proximal part of the tunnel, and examined the relationship between the MMA piercing the tunnel to a surface landmark, i.e., the junction of the sphenoparietal, sphenosquamosal, and squamosal sutures.

Results: We found 59 tunnels on 78 sides (75.6%); 2 were at the branching of the MMA on one side. The tunnels were located on the temporal side of the lesser wing of the sphenoid bone. The length of the tunnel and the distance from the superior orbital fissure were 3–23 mm (mean: 12.2 mm) and 11–33 mm (mean: 18.9 mm), respectively. Most tunnels (86.4%) were bilateral; in 67.8% of the specimens the MMA piercing the tunnel was just beneath the surface landmark.

Conclusion: As we found a high incidence of bony tunnel formation in the middle meningeal groove, actual findings can be different from the accepted nomenclature. If a tunnel exists, the MMA is easily damaged upon cracking of the lesser wing during bone flap elevation. Recognition of this anatomy may render pterional craniotomy safer.

anatomy - bony tunnel - middle meningeal groove - pterional craniotomy

References

• 1 Crossman AR. Cranial meninges. In: Standring S, ed. Gray’s Anatomy, 39th edn. Edinburgh: Elsevier Churchill Livingstone 2005: 275-285
• 2 Liu Q, Rhoton  Jr  AL. Middle meningeal origin of the ophthalmic artery.  Neurosurgery. 2001;  49 401-407
• 3 Perrini P, Cardia A, Fraser K. et al . A microsurgical study of the anatomy and course of the ophthalmic artery and its possibly dangerous anastomoses.  J Neurosurg. 2007;  106 142-150
• 4 Padget DH. The development of the cranial arteries in the human embryo.  Contrib Embryol. 1948;  32 205-261
• 5 Hayreh SS, Dass R. The ophthalmic artery. I. Origin and intracranial and intracanalicular course.  Br J Ophthalmol. 1962;  46 65-98
• 6 Shima K, Kawasaki T, Shimizu A. et al . An ophthalmic artery occlusion after a craniotomy using the pterional approach. A report of three cases, one resulting in blindness.  Jpn J Neurosurg. 1995;  4 163-169
• 7 Miller CF II, Spetzler RF, Kopaniky DJ. Middle meningeal to middle cerebral arterial bypass for cerebral revascularization. Case report.  J Neurosurg. 1979;  50 802-804
• 8 Nishikawa M, Hashi K, Shiguma M. Middle meningeal-middle cerebral artery anastomosis for cerebral ischemia.  Surg Neurol. 1979;  12 205-208

Correspondence