Table.

Radiographic evaluation and clinical semiology of syringomyelia

Factor	Idiopathic	Chiari I	Control
No. of patients	17	17	32
Age, y	49.4 ± 10.9	48.7 ± 11.6	50.2 ± 9.2
Age at onset, y	26.2 ± 10.9	27.4 ± 11.5
MRI features
Tonsillar herniation, mm	0 ± 0	7.6 ± 1.5
PF height, mm	24.5 ± 3.4*	25.5 ± 4.3*	32.0 ± 3.0
Klaus index, mm	33.4 ± 3.5*	34.5 ± 6.5	38.0 ± 5.0
Distance pm, mm	16.5 ± 2.4*	13.6 ± 3.0†	19.0 ± 3.0
Length of so, mm	36.8 ± 4.5*	36.5 ± 4.6*	41.0 ± 5.0
Length of cl, mm	40.0 ± 3.5*	39.3 ± 4.2*	43.4 ± 4.4
Boogaard angle, °	145.3 ± 6.7*	144.3 ± 10.7*	133.8 ± 6.5*
Distance c, mm	3.8 ± 2.6*	1.4 ± 1.5*†	8.8 ± 2.5
Ventral CSF space, mm	5.7 ± 1.9*	6.1 ± 2.9*	12 ± 2.3
Dorsal CSF space, mm	11.5 ± 4.7*	0.8 ± 1.3*†	19 ± 2.3
Syrinx sagittal diameter, mm	2.7 ± 1.9	5.5 ± 4.7†	N/A
Small cerebellar cisterns, %	17 (100)	17 (100)
Cervicomedullary kinking, %	2 (12)	9 (53)†
4th ventricle to syrinx communication, %	0 (0)	0 (0)
Clinical features, %
Segmental sensory loss	16 (94)	15 (88)
Muscle atrophy	10 (59)	11 (65)
Pyramidal signs	14 (82)	12 (71)
Impaired position sense	6 (35)	5 (29)
Suboccipital headache	4 (24)	4 (24)
Ataxia	8 (47)	5 (29)
Scoliosis/kyphosis	9 (53)	10 (59)

Values are means ± SD or no. (%).

^*Significant, p < 0.05, compared with control.

^†Significant, p < 0.05, compared with idiopathic syringomyelia.

PF = posterior fossa; pm = pontomedullary junction to foramen magnum; so = supraocciput; cl = clivus (apex of dorsum sellae to basion).