Percutaneous Transosseous Translaminar
Percutaneous Transosseous Translaminar
Approach for Thecal Sac Access in Advanced
Ankylosing Spondylitis with Instrumented
TECHNICAL NOTE Posterior Spinal Fusion
B.P. Liu SUMMARY: A novel transosseous approach for percutaneous access of the lumbar subarachnoid
A. Aghaei Lasboo space is described in a patient with advanced ankylosing spondylitis (AS) and instrumented spinal
fusion who presented for myelography. Use of a coaxial threaded bone biopsy system to provide
transosseous access to the thecal sac, imaging findings, and outcome are discussed. This technique
T.A. Hijaz provided access to an otherwise inaccessible subarachnoid space and is an alternative approach in the
S.F. Futterer setting of advanced AS or posterior spinal fusion.
A nkylosing spondylitis (AS) is a seronegative spondyloar-
thropathy that can affect the sacroiliac joints, vertebral
bodies, intervertebral disks, spinal facet joints, costovertebral
positioning/comfort issues. It was decided to attempt access by dril-
ling through the lamina and coaxially introducing a spinal needle into
the thecal sac.
joints, costotransverse joints, and the paravertebral soft tis- The patient was placed prone on the CT table and made comfort-
sues, including tendon and ligament attachments.1 In the set- able, which required significant bolstering due to his fixed spinal
ting of AS, access to the subarachnoid space for myelography kyphosis. After initial scanning of the lumbar spine, a left paramedian
can be difficult or impossible by using conventional lumbar approach at L2–3 was selected due to the relative thinness of the os-
puncture techniques due to spinal ankylosis, associated soft- seous fusion in that position. Through a small incision, a 14-gauge
issue abnormalities, and prior spinal fusions.2 We describe a 9.5-cm Bonopty penetration cannula and stylet (Radi Medical Sys-
novel controlled transosseous approach to access the lumbar tems) were advanced toward the target lamina. Upon reaching the
subarachnoid space safely in a patient with complete spinal bony surface, the stylet was exchanged for the 15-gauge 12.2-cm drill
fusion from AS and prior surgical fusion by using the Bo- stylet. Once the drill bit was anchored within the bone, a scan was
nopty Bone Biopsy System (Radi Medical Systems, Uppsala obtained to confirm position. The drill was then slowly advanced,
Sweden). with periodic CT imaging, through the bone and the ossified ligamen-
tum flavum until the dorsal epidural space was accessed. The pene-
Technical Report tration cannula was advanced over the tip of the drill into the dorsal
A 44-year-old man with advanced AS and prior posterior spinal fu- epidural space, the drill was exchanged for a 22-gauge 15-cm Quincke
sion from the occiput to the pelvis presented with progressive my- spinal needle (Avid Medical, Toano, Virginia), and the thecal sac was
elopathy (Fig. 1). CT and MR imaging were attempted but were lim- accessed (Fig 3A, -B). CSF was obtained, and approximately 12 mL of
ited due to metal artifacts from the extensive spinal fusion hardware. iohexol (Omnipaque-240; Nycomed, Princeton, New Jersey) was in-
There were findings of upper and midthoracic spinal cord syringohy- jected. The patient was transferred to his stretcher and manipulated to
dromyelia on MR imaging, but the presence/absence of subarachnoid allow the contrast to move throughout the spinal subarachnoid space
adhesions, which could be causative, could not be determined (Fig 2). (SAS). A CT scan of the entire spine was then obtained.
A total spine myelogram was requested via the C1–2 approach. CT myelography revealed multiple complex subarachnoid adhe-
Review of prior cervical imaging showed extensive ossification at sions with compartmentalization of the SAS in the lower thoracic
the craniocervical junction and a diminutive dorsal CSF space at region and cord compression. A complete block of CSF flow was
C1–2. The C1–2 approach was deemed unsafe. A decision was made identified at T8 (Fig 3C). The patient was taken to surgery for T5-T8
to attempt myelography via a lumbar approach by using CT guidance. laminectomy/decompression, lysis of subarachnoid adhesions, and
The preprocedural CT scan showed complete ankylosis across the myelotomy for decompression of the spinal cord syringohydromy-
facets joints and between the lamina in conjunction with prior surgi- elia. At surgery, the initial durotomy exposed a SAS devoid of visible
cal bone graft fusion material over the posterior elements, resulting in pulsatile CSF flow and a complex web of subarachnoid adhesions.
a confluent continuous osseous barrier. A classic interlaminar lumbar These adhesions were carefully taken down, which re-established pul-
puncture with standard spinal needles was not possible due to the satile CSF flow. Two separate myelotomies were performed through
extent of ossification/fusion. A lumbar transforaminal approach was the dorsal cord of the thoracic spinal cord for decompression of the
considered but dismissed due to anatomic considerations and patient syringohydromyelia. A postoperative myelography was requested to
assess the extent of the lysis, which was performed by using the same
method as the preoperative myelography, and showed some de-
Received April 21, 2009; accepted April 25.
creased compartmentalization of the SAS. On clinical follow-up, the
From Feinberg School of Medicine of Northwestern University, Department of Radiology, patient had improved symptomatically.
Please address correspondence to Matthew T. Walker, MD, Department of Radiology,
Northwestern University, 676 North St. Clair St, Suite 1400, Chicago, IL 60611; e-mail: Discussion
[email protected] AS is a seronegative spondyloarthropathy that results in pro-
DOI 10.3174/ajnr.A1701 gressive fusion of the sacroiliac joints and axial skeleton.1,3 AS
AJNR Am J Neuroradiol 31:193–95 Jan 2010 www.ajnr.org 193
Fig 2. Sagittal fast spin-echo T2-weighted image of the thoracic spine demonstrates
syringohydromyelia of the thoracic spinal cord with expansion of the cord (arrows). The
syrinx extends from T2-T11. Portions of the spinal canal are obscured by artifacts.
cord compression, whereas CT myelography confirmed ob-
struction by an epidural process, which was histologically
shown to represent bone with trabecula interspersed by fi-
brous granulation tissue and inflammatory cell infiltrate. The
authors rightly concluded that CT alone was not a satisfactory
method to study these lesions and that emphasis should be
placed on contrast studies such as CT myelography or MR
imaging. Despite advances in MR imaging technology, there
remain many circumstances in which older technology such as
CT myelography can be beneficial. Although the pathology in
our patient was subarachnoid adhesions and not an epidural
process, the same nondiagnostic results from noncontrast CT
and artifacts-distorted MR imaging created a clinical dilem-
ma: How can we safely access the thecal sac for a diagnostic
myelography in a patient with complete spinal ankylosis?
The coaxial system we used differs from other bone biopsy
systems in that it was designed with a drill stylet. In normal or
osteoporotic bone, the 15-gauge drill stylet can be advanced at
Fig 1. Lateral projection scoliosis radiograph demonstrates instrumented posterior spinal
exactly the spiral thread profile of the drill with each turn. This
fusion from the occiput to the pelvis. There is an accentuated upper thoracic kyphosis and
positive sagittal imbalance. allows controlled advancement through the bone under man-
ual pressure. In well-mineralized or sclerotic bone, the drill
is an inflammatory process characterized by enthesitis and sy- stylet does not advance at the rate of the spiral thread profile
novitis, leading to ossification of ligamentous structures such but can cut through the bone with only manual pressure,
as the annulus fibrosis and ankylosis of the joints, including though more turns and pressure are required to advance
the apophyseal joints. The disease manifests clinically with through the bone to the target. Controlled advancement of the
pain and decreased range of motion of the spine. As the disease coaxial system into the dorsal epidural space is preferable for sub-
progresses, the entire spine may fuse together as 1 segment. sequent safe delivery of the spinal needle into the thecal sac.
Patients with AS often require posterior spinal fusion to stabi- The use of the Bonopty Bone Biopsy System for controlled
lize or correct the spinal deformity.4 In advanced disease, ex- access of bony lesions has been described, but its use for tran-
tensive ossification can create a significant barrier to accessing sosseous thecal sac access has not.6 It is easy to use, and, in 1
the SAS. Any surgical instrumented fusion only adds to the study, was rated among the easiest to use when compared with
complexity of access. When the spinal canal and SAS require 8 commonly used commercially available bone biopsy nee-
evaluation and MR imaging is not diagnostic, CT myelogra- dles.7 This technique is useful in the spine and other osseous
phy can play a role. locations when a fine, precise, controlled transosseous needle
Jobanputra et al5 reported on a patient with AS and disko- advancement is desired. Although this technique was used for
vertebral destruction who presented with signs of spinal cord lumbar puncture and myelography in the setting of AS and
compression. A noncontrast CT scan showed no evidence of instrumented spinal fusion, it has other potential uses, includ-
194 Liu AJNR 31 Jan 2010 www.ajnr.org
Fig 3. A, Axial CT scan through the L2–3 level with the patient prone shows the cannula (arrow) traversing a 2.5-cm thickness of bone graft, lamina, and ossified ligamentum flavum. B,
Axial CT scan demonstrates placement of the 22-gauge spinal needle (arrowhead) through the cannula (arrow) and into the SAS. The needle tip was ventral, and though we did not puncture
the ventral dura, that is a theoretic risk. In future attempts, we plan to measure the distance to the middle of the thecal sac and use a depth gauge or collar to identify our intended depth.
We will then secure that depth with a clamp on the spinal needle so that it cannot inadvertently advance with gravity. C, Sagittal reconstruction of the CT myelogram demonstrates
subarachnoid compartmentalization, adhesions, and a compete myelographic block ventrally at T8 (arrow) and dorsally at T12 (arrowhead).
ing controlled access to the epidural space for biopsies and 3. Borenstein D. Arthritic disorders. In: Herkowitz HN, Garfin SR, Eismont FJ, et
al, eds. The Spine. 5th ed. Philadelphia: Saunders; 2006:729 –30
direct synovial cyst punctures/fenestrations. At a minimum, 4. Hu SS, Ananthakrishnan D. Ankylosing spondylitis. In: Herkowitz HN,
this approach can be added to the interventional spine arma- Garfin SR, Eismont FJ, et al, eds. The Spine. 5th ed. Philadelphia: Saunders:
mentarium for consideration in unique circumstances. 2006:763–71
5. Jobanputra P, Kirkham B, Duke O, et al. Discovertebral destruction in anky-
losing spondylitis complicated by spinal cord compression. Ann Rheum Dis
References 1988;47:344 – 47
1. Hermann KG, Althoff CE, Schneider U, et al. Spinal changes in patients with 6. DeFriend DE, Smith SP, Hughes PM. Percutaneous laser photocoagulation of
spondyloarthritis: comparison of MR imaging and radiographic appearances. osteoid osteomas under CT guidance. Clin Radiol 2003;58:222–26
Radiographics 2005;25:559 – 69, discussion 569 –70 7. Roberts CC, Morrison WB, Leslie KO, et al. Assessment of bone biopsy needles
2. Bartleson JD, Cohen MD, Harrington TM, et al. Cauda equina syndrome sec- for sample size, specimen quality and ease of use. Skeletal Radiol 2005;34:
ondary to long-standing ankylosing spondylitis. Ann Neurol 1983;14:662– 69 329 –35
AJNR Am J Neuroradiol 31:193–95 Jan 2010 www.ajnr.org 195
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