A detailed morphologic and functional magnetic resonance imaging study of the craniocervical junction in adolescent idiopathic scoliosis.
METHODS
Conventional and phase-contrast magnetic resonance (MR) imaging were used to evaluate the morphology and cerebrospinal fluid (CSF) flow dynamics at craniocervical junction in adolescent idiopathic scoliosis (AIS).


OBJECTIVE
To determine the morphology of cerebellar tonsil, foramen magnum, and dynamic flow of CSF at the craniocervical junction in AIS patients versus normal controls and their correlation with somatosensory cortical evoked potentials (SSEP).


BACKGROUND
Previous studies have documented obstructed CSF flow in patients with Chiari I malformation. Low-lying cerebellar tonsils and syringomyelia are also observed in AIS patients. We sought to investigate whether disturbed CSF flow is also evident in AIS subjects at the foramen magnum level and its association with level of cerebellar tonsils and dimensions of foramen magnum.


METHODS
Conventional and phase-contrast MR were performed in 105 adolescent girls (69 AIS subjects and 36 age-matched controls). Measurements of cerebellar tonsillar level related to the basion-opsithion (BO) line, anteroposterior (AP), transverse (TS) diameter, and area of foramen magnum, and peak velocity of CSF flow in both the anterior and posterior subarachnoid space through foramen magnum were obtained. Correlations were made among different parameters and SSEP findings.


RESULTS
A total of 42% of subjects in the AIS group had the cerebellar tonsillar tip positioned 1 mm below the BO line. The cerebellar tonsillar level in AIS subjects was significantly lower than the median tonsillar level in normal controls (P < 0.01). The AP diameter and area of foramen magnum were significantly larger in AIS subjects when compared with normal controls (P < 0.05), but the peak CSF velocities through foramen magnum showed no significant difference (P > 0.05).


CONCLUSIONS
Peak CSF velocities through foramen magnum were not significantly different in AIS subjects despite the presence of low-lying cerebellar tonsils. This might be explained by the compensatory effect of larger foramen magnum in AIS subjects.
Chu
Winnie C W
WC
Department of Diagnostic Radiology and Organ Imaging, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong. winnie@med.cuhk.edu.hk
Man
Gene C W
GC
Lam
Wynnie W M
WW
Yeung
Benson H Y
BH
Chau
Wai-Wang
WW
Ng
Bobby K W
BK
Lam
Tsz-Ping
TP
Lee
Kwong-Man
KM
Cheng
Jack C Y
JC
D000293:Adolescent; D000367:Age Factors; D001139:Arnold-Chiari Malformation / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D001269:Atlanto-Occipital Joint / Q000002:abnormalities / Q000503:physiopathology; D002531:Cerebellum / Q000002:abnormalities / Q000473:pathology / Q000503:physiopathology; D015170:Cerebrospinal Fluid Pressure / Q000502:physiology*; D001270:Cervical Atlas / Q000002:abnormalities / Q000503:physiopathology; D002648:Child; D015897:Comorbidity; D003388:Cranial Fossa, Posterior / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D005539:Foramen Magnum / Q000002:abnormalities / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D009777:Occipital Bone / Q000002:abnormalities / Q000503:physiopathology; D011237:Predictive Value of Tests; D012600:Scoliosis / Q000150:complications*; D013346:Subarachnoid Space / Q000473:pathology* / Q000503:physiopathology; D013595:Syringomyelia / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology