Imaging Diagnosis-Vertebral Canal Porcupine Quill With Presumptive Secondary Arachnoid Diverticulum

Abstract

A 3-year-old Gordon Setter developed cervical hyperesthesia and a stiff gait. Upon magnetic resonance (MR) imaging, an arachnoid diverticulum was detected at the C1 level. Upon surgical resection, a porcupine quill was identified within the vertebral canal in the area of the cyst. At a retrospective review of the MR images, the quill appeared as a circular well-demarcated T2-hypointense lesion. Porcupine quill migrations are common in the dog but migration into the central nervous system is rare. r

Optimal Magnetic Resonance Imaging of the Spine

“…Outside the spinal cord, contrast enhancement reflects increased vascularity of lesions such as meningitis, extramedullary–intradural and extradural masses, discospondylitis, paraspinal inflammation, abscesses, and sinus tracts 15,16 . Areas of nonenhancement indicate avascular areas such as spinal empyema, paraspinal fluid accumulations, and foreign bodies 17 . Again, subtraction may be helpful, especially for areas of contrast enhancement within or close to fat such as radiculitis or panniculitis; however, it must be remembered that contrast enhancement is a nonspecific finding.…”

“…15,16 Areas of nonenhancement indicate avascular areas such as spinal empyema, paraspinal fluid accumulations, and foreign bodies. 17 Again, subtraction may be helpful, especially for areas of contrast enhancement within or close to fat such as radiculitis or panniculitis; however, it must be remembered that contrast enhancement is a nonspecific finding. Contrast enhancement around disc extrusions due to provoked meningitis or granulation tissue may mimic other pathology.…”

Migrating sewing needle in the cervical vertebral canal in a dog

“…Migration of plant material to the CNS is rare (Johnston and Summers 1971, Leskovar and others 2003, Dennis and others 2005, Granger and others 2007, Mateo and others 2007, Sutton and others 2010, Whitty and others 2013). Other foreign materials that can reach the CNS and cause pathology in small animals are sticks (Brockman and Trout 1991, Pratt and others 1999, Rayward 2002, Potanas and others 2011, Tanaka and others 2012), porcupine quills (Daoust 1991, Schneider and others 2010, Sauvé and others 2012), or needles (McCandlish 1978). …”

“…Clinical signs associated with foreign bodies in the vertebral canal can be caused by direct injury to the spinal cord by the foreign material, or related to haemorrhage, infection or granuloma formation secondary to the intruding material (Johnston and Summers 1971, Brockman and Trout 1991, Pratt and others 1999, Rayward 2002, Leskovar and others 2003, Dennis and others 2005, Granger and others 2007, Mateo and others 2007, Platt and others 2007, Hicks and Bagley 2008, Smith and Fitzpatrick 2009, Joslyn and others 2010, Schneider and others 2010, Sutton and others 2010, Potanas and others 2011, Tanaka and others 2012, Whitty and others 2013). Needles are very thin and of an inert material, so direct injury of the spinal cord should be theoretically minimal.…”

Arachnoid diverticulum diagnosis following treatment of cryptococcal meningitis in a dog

“…Other concurrent CNS diseases included the following: vertebral malformations, intervertebral disk extrusion or protrusion, atlantoaxial instability, vertebral canal stenosis attributable to articular process hypertrophy, and fibrocartilaginous embolism. Diverticulum formation has also been reported secondary to a porcupine quill foreign body .…”