MR Imaging Features of Middle Cranial Fossa Encephaloceles and Their Associations with Epilepsy

D.R. Pettersson; K.S. Hagen; N.C. Sathe; B.D. Clark; D.C. Spencer

doi:10.3174/ajnr.A6798

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FIG 1.
Large left middle cranial fossa encephalocele in a patient with left temporal lobe epilepsy. Coronal STIR image (A, arrows) depicts a focally prominent CSF space and distorted temporal lobe parenchyma surrounded by the scalloped bone margins of the encephalocele. Axial T2 TSE image (B) shows a distorted, stretched appearance of a left temporal lobe gyrus (open arrow) extending into the encephalocele (solid arrows) and asymmetric enlargement of the adjacent intracranial subarachnoid space (asterisk).
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FIG 2.
Bilateral middle cranial fossa encephaloceles in a patient with no history of seizure. Coronal STIR image depicts distortion and thinning of temporal lobe parenchyma (solid arrows), which appears adherent to the floor of the encephalocele, and asymmetric enlargement of the adjacent intracranial subarachnoid space (asterisk). A small middle cranial fossa encephalocele is present on the left (open arrow), with associated mild parenchymal distortion.

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Table 1:

MR imaging characteristics of encephaloceles compared between patients with a history of seizure and those with no history of seizure^{^a}

Variable	Total (n = 77)	History of Seizure (n = 35)	No History of Seizure (n = 42)	P
Location of encephaloceles				.91
Left	22 (28.6)	10 (28.6)	12 (28.6)
Right	16 (20.8)	8 (22.9)	8 (19.1)
Bilateral	39 (50.7)	17 (48.6)	22 (52.4)
Side of largest encephalocele				.80
Left	43 (55.8)	19 (54.3)	24 (57.1)
Right	34 (44.2)	16 (45.7)	18 (42.9)
Total No. of encephaloceles				.12
1	26 (33.8)	15 (42.9)	11 (26.2)
>1	51 (66.2)	20 (57.1)	31 (73.8)
Median No. of sextants^{^b} containing encephaloceles	3 (2)	2 (2)	3 (3)	.21
Largest encephalocele
Depth (mm)	5 (3)	5 (3)	5.5 (3)	.88
Areal extent (mm²)	117 (142)	119 (144)	117 (154)	.93
Volume (mm³)	368 (538)	374 (512)	364 (632)	.76
Morphologic distortion of adjacent brain parenchyma				.51
Minimal	11 (14.3)	4 (11.4)	7 (16.7)
Mild	21 (27.3)	10 (28.6)	11 (26.2)
Moderate	32 (41.6)	17 (48.6)	15 (35.7)
Severe	13 (16.9)	4 (11.4)	9 (21.4)
Longest single dimension of distorted parenchyma adjacent to largest encephalocele (mm)	13 (11)	14 (13)	13 (11)	.54
Presence of adjacent encephalomalacia	9 (11.7)	2 (5.7)	7 (16.7)	.14

↵a Data are median (interquartile range) or No. (%).
↵b Middle cranial fossa sextants.

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Table 2:

MR imaging characteristics of middle cranial fossa encephaloceles compared in patients with a history of temporal lobe epilepsy and those with no history of seizure^{^a}

Variable	Total (n = 62)	History of Temporal Lobe Epilepsy (n = 20)	No History of Seizure (n = 42)	P
Encephalocele side				.86
Left	17 (27.4)	5 (25)	12 (28.6)
Right	30 (21.0)	5 (25)	8 (19.1)
Bilateral	32 (51.6)	10 (50)	22 (52.4)
Side of largest encephalocele				.60
Left	34 (54.8)	10 (50.0)	24 (57.1)
Right	28 (45.2)	10 (50.0)	18 (42.9)
Total No. of bilateral encephaloceles				.14
1	20 (32.3)	9 (45.0)	11 (26.2)
>1	42 (67.7)	11 (55.0)	31 (73.8)
Median No. of sextants^{^b} containing encephaloceles	3 (2)	3 (2)	3 (3)	.23
Largest encephalocele
Depth (mm)	5 (3)	4 (2.5)	5.5 (3)	.43
Areal extent (mm²)	117 (142)	149 (225.5)	117 (154)	.92
Volume (mm³)	368 (538)	423 (513)	364 (632)	.74
Morphologic distortion of adjacent brain parenchyma				.83^{^c}
Minimal	9 (14.5)	2 (10.0)	7 (16.7)
Mild	17 (27.4)	6 (30.0)	11 (26.2)
Moderate	24 (38.7)	9 (45.0)	15 (35.7)
Severe	12 (19.4)	3 (15.0)	9 (21.4)
Longest single dimension of distorted parenchyma adjacent to largest encephalocele (mm)	13 (11)	15.5 (15)	13 (11)	.53
Presence of adjacent encephalomalacia	7 (11.3)	0 (0.0)	7 (16.7)	.09^{^c}