Anat Cell Biol.  2019 Dec;52(4):406-413. 10.5115/acb.18.200.

Reappraising the neurosurgical significance of the pterion location, morphology, and its relationship to optic canal and sphenoid ridge and neurosurgical implications

• Kamath VG
• Hande M

• KMID: 2466693
• DOI: http://doi.org/10.5115/acb.18.200

Abstract

Frontolateral craniotomy procedures have advanced from conventional craniotomy to mini-craniotomy, and to contemporary keyhole surgery. In this context, it is important for the neurosurgeon to precisely locate the pterion. The distance of the pterion center from midpoint of zygomatic arch and posterolateral margin of frontozygomatic suture was studied bilaterally in 50 whole adult skulls in Indian ethnic group. The depth of optic canal and sphenoid ridge from the pterion was recorded bilaterally in fifty cut adult skulls and fifteen three-dimensional computed tomography scans. The suture length, thickness, and morphology were studied. The data were analyzed using SPSS software, two-tailed Student's t test, binary logistic regression and receiver operating characteristic curve for sexual dimorphism. The pterion center was located at a mean distance of 37.02 mm above the midpoint of zygomatic arch, 28.20 mm behind the posterolateral margin of frontozygomatic suture, 42.73 mm lateral to the optic canal and 10.59 mm from the sphenoid ridge. The location did not exhibit sexual dimorphism. In 20% cases the pterion center was 40 mm or more above the midpoint of the zygomatic arch and in 5% cases 35 mm or more posterior to the posterolateral margin of frontozygomatic suture. The mean suture length was 10±3 mm. The mean thickness at the center of the pterion was 3.52±1.45 mm. The commonest variety was sphenoparietal followed by frontotemporal, epipteric, and stellate types. A thorough knowledge of these dimensions has innumerable neurosurgical implications in resection of sellar, parasellar, and paraclinoid tumors and circulatory aneurysms.

Keyword

Brain tumors; Optic canal; Sphenoid ridge; Pterion; Trans-Sylvian approach

MeSH Terms

Adult
Aneurysm
Brain Neoplasms
Craniotomy
Ethnic Groups
Humans
Logistic Models
Neurosurgeons
ROC Curve
Skull
Sutures
Zygoma

Figure

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  Fig. 1 The technique of marking the center of the pterion externally. CP marks the location of the pterion. Type, sphenoparietal. CP, center of the pterion; F, frontal bone; P, parietal bone; S, sphenoid bone; T, temporal bone.

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  Fig. 2 The location of the pterion as linear distances from specific landmarks. CP, center of the pterion; CPS, distance from the center of the pterion to the posterolateral margin of the frontozygomatic suture; CPZ, distance from the center of the pterion to the midpoint of the zygoma; F, frontal bone; FZ, the frontal process of the zygomatic bone with the fronto-zygomatic suture intervening; S, posterolateral margin of the frontozygomatic suture; Z, midpoint of the zygoma.

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  Fig. 3 The technique of measurement of the length of the suture. Type of pterion, sphenoparietal. C, distance between the points A and B and marks the length of the suture; F, frontal bone; P, parietal bone; S, sphenoid bone; T, temporal bone.

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  Fig. 4 The measurement of depth optic canal and the sphenoid ridge from the pterion. AB is a vertical line drawn at the lateral margin of the optic canal. IP-L is the horizontal distance from the internal location of the pterion to the lateral margin of the optic canal. IP-SR is the linear distance from the internal location of the pterion to the lateral end of the sphenoid ridge. IP, internal location of the pterion; OC, optic canal; SR, a point on the lateral end of the sphenoid ridge.

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  Fig. 5 The four patterns of the pterion as described by Murphy [3]. (A) Sphenoparietal. (B) Frontotemporal. (C) Stellate. (D) Epipteric. E, epipteric bone; F, frontal bone; P, parietal bone; S, sphenoid bone; T, temporal bone.

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  Fig. 6 Measurement of depth optic canal and the sphenoid ridge from the pterion in 3-dimensional computed tomography scan. IP-OC is the horizontal distance from the internal socation of the pterion to the lateral margin of the optic canal. IP-SR is the linear distance from the internal location of the pterion to the lateral end of the sphenoid ridge. IP, internal location of the pterion; OC, optic canal; SR, a point on the lateral end of the sphenoid ridge.

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