CASE 12636 Published on 12.04.2015

Spinal arachnoid cyst

Section

Neuroradiology

Case Type

Clinical Cases

Authors

W. Al-Obaydi, S. Patel.

Department of radiology,
Royal Derby Hospital,
Derby, UK
Email:waleed_obaydi@hotmail.com

Patient

56 years, female

Categories

Area of Interest Spine ; Imaging Technique MR

Procedure Imaging sequences ; Special Focus Cysts ;

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Clinical History

At 56-year-old lady cook presented to her GP with 6 months history of severe neck pain radiating to both shoulders and upper arms. The pain was worse following physical activity. Past medical history includes asthma, familial hypercholesterolaemia and diverticular disease. She was referred by her GP to a neurosurgeon.

Imaging Findings

T1, T2 and post-contrast weighted sagittal and axial MRI sequences. DWI was not performed. There was a large low T1 and high T2 signal intensity lesion which was intradural and extramedullary, causing compression and anterior plastering of the thoracic cord, starting from the T6/7 disc level to distal cord and filling in the lower central cord where it wrapped around the distal cord. Lower down within the lumbar region the spinal cord was very small and it was plastered on the anterolateral to the right aspect of the cord. The lesion was also noted to cause posterior scalloping of vertebral bodies and dural ectasia.
After administration of contrast there was no enhancement of this lesion. Modest multi-segmental cervical disc degeneration without spinal cord or nerve root involvement was seen.
A CT cerebral angiography showed no evidence of any vascular weakness, which might have bled to cause the spinal arachnoid cyst.

Discussion

Spinal arachnoid cysts are relatively uncommon lesions that may be intradural or extradural with the intradural variety being rare [1]. The majority of intradural spinal arachnoid cysts occur in the thoracic region with only 15% in the cervical region and 5% in the lumbar region [1]. About 80% of subarachnoid cysts are posterior to the spinal cord [2].
Acquired intradural cysts may be anterior, posterior or lateral to the spinal cord. Such secondary arachnoid cysts are believed to arise from arachnoiditis. This is caused by trauma (due to iatrogenic procedures like surgery and lumbar puncture), chemical meningitis (due to subarachnoid haemorrhage, contrast media and spinal anaesthetic agents), inflammatory meningitis (due to viruses, spirochetes or bacteria).
Depending on the location, size, and mechanism of origin, the clinical course varies between asymptomatic, incidentally-diagnosed cases [4] to severe myelopathy [5]. When they communicate freely with the subarachnoid space, fluctuating symptoms related to changes in CSF pressure may occur [6, 7].
MRI is the imaging modality of choice for spinal canal cysts [8]. It is useful to assess the size, nature and extent of the cystic lesion as well as the mass effect on the cord and associated signs of meningeal inflammation [9]. The cyst is usually of CSF intensity on the T1 and T2 weighted images [10]. The cyst demonstrates no evidence of contrast enhancement on post gadolinium images or diffusion restriction on the DWI imaging. There is usually decreased CSF flow within the cyst on phase-contrast imaging [11].
Incidental asymptomatic cysts are managed conservatively. When progressive neurological findings exist, surgical treatment is warranted. Surgical techniques include excision, fenestration, or placement of a cysto-subarachnoid shunt [3, 5].

Differential Diagnosis List

Spinal arachnoid cyst

Spinal epidermoid cyst

Herniated ventral cord

Final Diagnosis

Spinal arachnoid cyst

References

[1] Lee H-J et al (2001) Symptomatic spinal intradural arachnoid cysts in the pediatric age group: description of three new cases and review of the literature. Pediat Neurosurg 35:181–7. (PMID: 11694795)

[2] Osborn AG (1994) Tumours, cysts, and tumour like lesions of the spine and spinal cord. diagnostic neuroradiology. St Louis, MO: Mosby Year Book, Inc., 876–918

[3] Kazan S, Ozdemir O, Akyuz M, Tuncer R (1999) Spinal intradural arachnoid cysts located anterior to cervical spinal cord: report of two cases and review of literature. J Neurosurg (Spine 2) 91:211–5 (PMID: 10505507)

[4] Teng P, Rudner N (1960) Multiple arachnoid diverticula. Arch Neurol 2: 348–356 (PMID: 13837415)

[5] Osenbach RK, Godersky JC, Traynelis VC et al (1992) Intradural extramedullary cysts of the spinal canal: clinical presentation, radiographic diagnosis, and surgical management. Neurosurgery 30:35–42 (PMID: 1738453)

[6] Masuzawa H, Nakayama H, Shitara N, Suzuki T (1981) Spinal cord herniation into a congenital arachnoid cyst causing Brown-Séquard syndrome: case report. J Neurosurg 55:983–986 (PMID: 7299475)

[7] McCrum C, Williams B (1982) Spinal extradural arachnoid pouches: report of two cases. J Neurosurg 57:849–852 (PMID: 7143073)

[8] Kjos BO, Brant-Zawadzki M, Kucharaczyk W, Kelly WM, Norman D, Newton TH. (1985) Cystic intracranial lesions: magnetic resonance imaging. Radiology 155:363–9. (PMID: 3983386)

[9] Lolge S, Chawla A, Shah J, Patkar D, Seth M. (2004) MRI of spinal intradural arachnoid cyst formation following tuberculous meningitis. The British Journal of Radiology 77 (2004), 681–684 (PMID: 15326049)

[10] Khosla A, Wippold FJ. (2002) CT myelography and MR imaging of extramedullary cysts of the spinal canal in adult and pediatric patients. AJR Am J Roentgenol 178 (1): 201-7. (PMID: 11756120)

[11] Brugières P, Malapert D, Adle-biassette H et-al. (1999) Idiopathic spinal cord herniation: value of MR phase-contrast imaging. AJNR Am J Neuroradiol 20 (5): 935-9 (PMID: 10369369)

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