Felis ISSN 2398-2950

Spine: arachnoid cyst

Synonym(s): Leptomeningeal cyst, meningeal cyst, subarachnoid cyst, spinal arachnoid diverticula (SAD

Contributor(s): Peter Dickinson, Laurent Garosi

Introduction

  • Very uncommon condition, only seven reports in the literature.
  • Also called leptomeningeal cyst, meningeal or subarachnoid cyst.
  • The pathophysiology behind the formation of SAD is not well understood but is broadly considered to be either congenital or acquired in origin with the former being more common.
  • The majority of reports suggest that congenital SAD arise from abnormal development of the arachnoid architecture during embryonic development.
  • Intradural arachnoid diverticulae is the preferred terminology.
  • Cause: Possibly congenital malformation or second degree to spinal cord injury Spine: fracture / luxation Spinal cord: concussion. Also possibly second degree to inflammatory disease or abnormal development Spina bifida (progressive).
  • Signs: progressive myelopathy Degenerative myelopathy or neurological deficits.
  • Diagnosis: myelography, CT myelography, MRI.
  • Treatment: surgical decompression.
  • Prognosis: unknown in cats but possibly good with prompt surgical intervention.

Pathogenesis

Etiology

  • Unclear.
  • The pathophysiology behind the formation of SAD is not well understood but is broadly considered to be either congenital or acquired in origin with the former being more common.
  • The majority of reports suggest that congenital SAD arise from abnormal development of the arachnoid architecture during embyronic development.
  • Alterations in CSF flow dynamics have also been suggested as a possible cause with proposed functional one-way valves at the cranial aspect of the lesions that open periodically with fluctuations in CSF pressure.
  • The pathophysiology of acquired SAD appears even less well understood, but altered CSF flow dynamics secondary to spinal disease causing scarring, inflammation or fibrin accumulation may play a role.

Timecourse

  • May be asymptomatic until the cat becomes adult. The cases published so far in the literature did not show signs before 5 to 7 years.
  • Once signs develop - slowly progressive over a few weeks.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Sugiyama T, Simpson D J (2009) Acquired arachnoid cyst in a cat. Aust Vet J 87 (7), 296-300 PubMed.
  • Schmidt M J, Schachenmayr W, Thiel C et al (2007) Recurrent spinal arachnoid cyst in a cat. J Feline Med Surg (6), 509-513 PubMed.
  • Thiel C, Lautersack O (2004) Spinal arachnoid cyst of a cat - case report of a rare illness. Kleintierpraxis 49 (3), 173-179 VetMedResource.
  • Galloway A M, Curtis N C, Sommerlad S F et al (1999) Correlative imaging findings in seven dogs and one cat with spinal arachnoid cysts. Vet Radiol & Ultrasound 40 (5), 445-452 PubMed.
  • Vignoli M, Rossi F & Sarli G (1999) Spinal subarachnoid cyst in a cat. Vet Radiol & Ultrasound 40 (2), 116-119 PubMed.
  • Shamir M H, Shahar R & Aizenberg I (1997) Subarachnoid cyst in a cat. JAAHA 33 (2), 123-125 PubMed.
  • Grevel V, Schmidt-Oechtering G U, Harms N (1989) Spinal arachnoid cyst in a cat. Kleintierpraxis 34 (2), 55-66 VetMedResource.


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