AJR 2003; 181:1155-1156
© American Roentgen Ray Society
Terminal Spine of Agave Plant Extracted from Patient's Spinal Cord
Lance H. Borup,
John J. Meehan,
Judson M. Severson and
Kevin Kaufman
Osteopathic Medical Center of Texas Fort Worth, TX 76107
Spinal cord injuries from retained foreign bodies are rare. Cases involving
bullet fragments [1], knife
blade tips [2], and shards of
glass [1] have been reported.
To our knowledge, a plant spine extracted from a spinal cord has not
previously been reported.
An 18-year-old man presented to the emergency department with bilateral
lower extremity weakness and spasticity for 3 days. He had no significant
medical history. Physical examination revealed an afebrile man without
evidence of penetrating trauma. Sensation below the level of T5 was decreased.
The patient could not stand or walk without support and had patellar and
Achilles hyperreflexia and ankle clonus.
Sagittal and axial T1-weighted images of the thoracic spine after contrast
administration revealed an area of intramedullary spinal cord enhancement
measuring 3.5 x 1.5 x 1.5 cm at the level of the T4 vertebral
body. A linear focus of low signal was seen traversing the long axis of the
lesion (Fig. 1A). Abutting the
anteroinferior aspect of the mass at the T5 level was a thick well-defined
ring-enhancing lesion measuring 1.75 x 1.0 x 1.0 cm. The spinal
cord had diffuse fusiform expansion extending from the T1 to the T9 level. The
lesion was isointense to spinal cord on unenhanced T1-weighted images and
showed high signal on T2-weighted images. No extramedullary paraspinous soft
tissue or bony abnormalities were identified.
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Fig. 1A. —18-year-old man with bilateral lower extremity weakness and
inability to walk. Enhanced sagittal T1-weighted image reveals 5-cm elongated
structure having low signal intensity on all imaging sequences and traversing
spinal cord from left posterior inferior to right anterior superior aspect of
spinal cord at level of T4. This represents agave terminal spine. Surrounding
enhancement of cord represents inflammatory changes and granulomatous
reaction. Area of thick well-defined ring enhancement (1.75 x 1.0
x 1.0 cm) at level of T5 anterior and inferior to needle represents
small Enterobacter agglomerans abscess. Fusiform expansion of cord at
T1–T9 level is also seen. No paraspinous soft-tissue abnormalities were
identified to indicate path that foreign body traversed.
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At surgery, a 5-cm needlelike plant spine was discovered and extracted from
the locally inflamed spinal cord. This plant spine corresponded in size and
location to the thin elongated low-signal-intensity lesion seen traversing the
spinal cord on MRI (Figs. 1A
and 1B). A small localized
abscess was also located anterior and inferior to the plant spine. The abscess
culture grew Enterobacter agglomerans, a gram-negative rod bacterium
commonly isolated from plants, water, and soil
[3]. On further questioning,
the patient admitted to falling backward from a fence onto the rigid terminal
spine of an agave plant (Fig.
1C).
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Fig. 1B. —18-year-old man with bilateral lower extremity weakness and
inability to walk. Enhanced axial T1-weighted image obtained through T4
vertebral level shows focus of right paracentral nonenhancement representing
agave terminal spine. Surrounding enhancement represents inflammatory changes
and granulomatous reaction.
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Fig. 1C. —18-year-old man with bilateral lower extremity weakness and
inability to walk. Photograph of agave terminal spine (top) is similar to 5-cm
agave terminal spine extracted from patient's thoracic spinal cord
(bottom).
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For foreign bodies penetrating perpendicular to the long axis of the
thoracic vertebrae, the area not shielded by laminae at each level is
approximately 1 x 2 mm in diameter. Although no tract for the terminal
spine was seen through the paraspinous soft tissue on MRI, the orientation of
the terminal spine in the spinal cord indicated that the agave needle likely
entered at an inferior oblique angle of approximately 60° and slightly to
the left of median. This angle and location of entrance of the needle
effectively made the opening between the laminae of vertebrae T5 and T6
approximately 5 x 5 mm. Flexion of the vertebrae as the patient fell
backward likely further increased the diameter of this intervertebral
space.
Although the situation is extremely rare, when a patient history is poor or
incomplete, a foreign body could be considered as a differential diagnosis for
intramedullary masses.
References
- Wu WQ. Delayed effects from retained foreign bodies in the spine
and spinal cord. Surg Neurol1986; 25:214
–218[Medline]
- Jones FD, Woolsey RE. Delayed myelopathy secondary to retained
intraspinal metallic fragment. J Neurosurg1981; 55:979
–982[Medline]
- Murray PR, Baron EJ, Pfaller MA, Tenover FC, Yolken RH, eds.
Manual of clinical microbiology, 7th ed. Washington,
DC: American Society for Microbiology, 1999:475
–476
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