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Vol. 33. Issue 6.
Pages 366-370 (November - December 2022)
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Vol. 33. Issue 6.
Pages 366-370 (November - December 2022)
Case Report
Dorsal arachnoid web: A rare cause of syringomyelia and myelopathy
Telaraña aracnoidea dorsal: una causa rara de siringomielia y mielopatía
Prasad Krishnana,
Corresponding author

Corresponding author.
, Sayan Dasb
a Department of Neurosurgery, National Neurosciences Centre, Calcutta, India
b Department of Radiology, Peerless Hospital, Calcutta, India
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Dorsal arachnoidal webs are condensations of arachnoidal tissue densely adherent to the pial surface of the posterior aspect of the dorsal spinal cord. Infrequently described in literature they disrupt the flow of CSF in the spinal subarachnoid space leading to syringomyelia and myelopathy. While there are several theories on their origin, the “scalpel sign” on magnetic resonance imaging is considered to be pathognomonic of this condition. An illustrative case of a 58 year old man with syringomyelia and dorsal cord indentation who presented with spastic paraparesis, gait instability, parasthesias and bilateral non radicular upper limb pain that resolved following excision of the web is described to highlight the importance of considering this diagnosis when cases of so called “idiopathic” syringomyelia are encountered.

Arachnoid web
Dorsal spine
Scalpel sign

Las membranas aracnoideas dorsales son condensaciones de tejido aracnoideo densamente adherido a la superficie pial de la cara posterior de la médula espinal dorsal. Descritas con poca frecuencia en la literatura, interrumpen el flujo del líquido cefalorraquídeo (LCR) en el espacio subaracnoideo espinal y provocan siringomielia y mielopatía. Si bien existen varias teorías sobre su origen, el «signo del bisturí» en la resonancia magnética se considera patognomónico de esta afección. Se describe un caso ilustrativo de un varón de 58 años con siringomielia e indentación medular dorsal que presentó paraparesia espástica, inestabilidad de la marcha, parestesias y dolor bilateral no radicular en miembro superior que se resolvió tras la exéresis de la telaraña para resaltar la importancia de considerar este diagnóstico cuando se encuentran casos de la llamada siringomielia «idiopática».

Palabras clave:
Telaraña aracnoidea
Columna dorsal
Signo de bisturí


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