Idiopathic intradural dorsal thoracic arachnoid cysts: A case series and review of the literature.
BACKGROUND
Spinal intradural arachnoid cysts (SIAC) are cerebrospinal fluid (CSF) filled sacs formed by arachnoid membranes and may be either idiopathic or acquired. Idiopathic cysts represent a separate entity and their aetiology remains uncertain. By far the most difficult differential diagnosis is distinguishing between idiopathic anterior spinal cord herniation (IASCH) and dorsal thoracic intradural arachnoid cysts (TIAC), due to their similarity in radiological appearance. Cine-mode (SSFP) is emerging as a novel technique in the diagnosis and operative planning of SIAC.


METHODS
Retrospective analysis of patients with idiopathic TIACs that were surgically managed at Royal North Shore Hospital and North Shore Private Hospital between November 2000 and November 2015.


RESULTS
Ten patients were included in this study. Age ranged from 20 to 77years with a mean age of 60years and a female preponderance. The most common clinical features were progressive gait ataxia and lower limb myelopathy. Radicular pain tends to improve following surgery, however gait ataxia may not.


CONCLUSIONS
While there are circumstances in which the distinction between dorsal thoracic intradural arachnoid cysts and idiopathic anterior spinal cord herniation are radiologically obvious, in cases where the appearances are less clear, cine-mode SSFP MRI imaging can provide an invaluable tool to differentiate these pathologies and lead the clinician towards the correct diagnosis and management. The mainstay of surgical management for dorsal TIACs is laminectomy and cyst excision or fenestration. Surgery for gait ataxia should be aimed towards preventing deterioration, while maintaining the potential for symptomatic improvement, whereas surgery for radicular pain should be curative.
Royal North Shore Hospital, Australia. Electronic address: heathfrench84@gmail.com.
Heath
H
French
Gold Coast Hospital, Australia. Electronic address: arjuna.js1@gmail.com.
Arjuna
A
Somasundaram
North Shore Private Hospital, Australia. Electronic address: mtbiggs1@gmail.com.
Michael
M
Biggs
Royal North Shore Hospital, Australia; North Shore Private Hospital, Australia. Electronic address: jfparkinson@me.com.
Jonathon
J
Parkinson
Royal Prince Alfred Hospital, Australia; North Shore Private Hospital, Australia. Electronic address: surgery@neurosurgeon.com.au.
Rodney
R
Allan
Royal North Shore Hospital, Australia; North Shore Private Hospital, Australia. Electronic address: jonathon@neurospine.com.au.
Jonathon
J
Ball
Royal North Shore Hospital, Australia; North Shore Private Hospital, Australia. Electronic address: drnlittle@bigpond.com.
Nicholas
N
Little
D000328:Adult; D000368:Aged; D016080:Arachnoid Cysts / Q000000981:diagnostic imaging / Q000601:surgery*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000000981:diagnostic imaging* / Q000601:surgery; D007796:Laminectomy / Q000009:adverse effects*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000209:etiology; D011183:Postoperative Complications / Q000209:etiology* / Q000517:prevention & control; D011859:Radiography; D013118:Spinal Cord Diseases / Q000000981:diagnostic imaging / Q000601:surgery*
Cine-mode MRI; Dorsal thoracic arachnoid cyst; Intradural arachnoid cysts; Myelopathy; Spinal arachnoid cyst; Steady state free precession MRI