Differentiation of idiopathic spinal cord herniation from dorsal arachnoid webs on MRI and CT myelography.
OBJECTIVE Dorsal arachnoid webs (DAWs) and spinal cord herniation (SCH) are uncommon abnormalities affecting the thoracic spinal cord that can result in syringomyelia and significant neurological morbidity if left untreated. Differentiating these 2 entities on the basis of clinical presentation and radiological findings remains challenging but is of vital importance in planning a surgical approach. The authors examined the differences between DAWs and idiopathic SCH on MRI and CT myelography to improve diagnostic confidence prior to surgery. METHODS Review of the picture archiving and communication system (PACS) database between 2005 and 2015 identified 6 patients with DAW and 5 with SCH. Clinical data including demographic information, presenting symptoms and neurological signs, and surgical reports were collected from the electronic medical records. Ten of the 11 patients underwent MRI. CT myelography was performed in 3 patients with DAW and in 1 patient with SCH. Imaging studies were analyzed by 2 board-certified neuroradiologists for the following features: 1) location of the deformity; 2) presence or absence of cord signal abnormality or syringomyelia; 3) visible arachnoid web; 4) presence of a dural defect; 5) nature of dorsal cord indentation (abrupt "scalpel sign" vs "C"-shaped); 6) focal ventral cord kink; 7) presence of the nuclear trail sign (endplate irregularity, sclerosis, and/or disc-space calcification that could suggest a migratory path of a herniated disc); and 8) visualization of a complete plane of CSF ventral to the deformity. RESULTS The scalpel sign was positive in all patients with DAW. The dorsal indentation was C-shaped in 5 of 6 patients with SCH. The ventral subarachnoid space was preserved in all patients with DAW and interrupted in cases of SCH. In no patient was a web or a dural defect identified. CONCLUSIONS DAW and SCH can be reliably distinguished on imaging by scrutinizing the nature of the dorsal indentation and the integrity of the ventral subarachnoid space at the level of the cord deformity.
Departments of 1 Diagnostic Radiology and Nuclear Medicine, and.
Randall
R
Schultz
Departments of 1 Diagnostic Radiology and Nuclear Medicine, and.
Andrew
A
Steven
Neurosurgery, University of Maryland Medical Center, Baltimore, Maryland; and.
Aaron
A
Wessell
Department of Radiology, Stanford University, Stanford, California.
Nancy
N
Fischbein
Neurosurgery, University of Maryland Medical Center, Baltimore, Maryland; and.
Charles A
CA
Sansur
Departments of 1 Diagnostic Radiology and Nuclear Medicine, and.
Dheeraj
D
Gandhi
Neurosurgery, University of Maryland Medical Center, Baltimore, Maryland; and.
David
D
Ibrahimi
Departments of 1 Diagnostic Radiology and Nuclear Medicine, and.
Prashant
P
Raghavan
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009192:Myelography; D012189:Retrospective Studies; D013118:Spinal Cord Diseases / Q000000981:diagnostic imaging* / Q000601:surgery; D013346:Subarachnoid Space / Q000000981:diagnostic imaging*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D014057:Tomography, X-Ray Computed; D055815:Young Adult
CT myelography; DAW = dorsal arachnoid web; MRI; SCH = spinal cord herniation; SPACE = sampling perfection with application-optimized contrasts using different flip-angle evolution; arachnoid web; congenital; cord herniation