Leakage of cerebro-spinal fluid after removal of a pedicular screw
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A case of cerebro-spinal fluid leakage occurring after the removal of a pedicular screw is reported. It allowed emphasizing the frequency of the dural tears in spinal surgery, particularly when pedicular screws are used. Moreover, the removal of screws having involved neurological complications can induce other lesions, such in the reported case. This removal procedure is not benign and requires precautions and a monitoring identical to the other spinal procedures.
KeywordsCerebro-spinal leak Burst fracture Pedicular screw Removal
Fuite de LCR après ablation d’une vis pédiculaire
Un cas de fistule de liquide céphalo-rachidien survenue après ablation d’une vis pédiculaire vertébrale est rapporté. Les brèches de la dure-mère sont fréquentes en chirurgie rachidienne, particulièrement lorsque des vis pédiculaires sont utilisées. De plus, l’ablation de vis responsables de complication neurologique peut elle aussi induire des lésions supplémentaires, comme dans le cas rapporté. L’ablation de vis pédiculaires n’est donc pas un geste bénin, mais nécessite les mêmes précautions et surveillance que les autres interventions rachidiennes.
Mots-clésLiquide céphalo-rachidien Fracture vertébrale Vis pédiculaire Ablation
The removal of spinal implants was considered as benign. The reported case revealing an unsuspected misplacement of a pedicular screw emphasizes the risk and the potential complications of such procedures.
A patient F.B., 19 years old, was admitted for a burst fracture of L1 after a fall in the stairs. An acute cauda equina syndrome was diagnosed. An intra-canalar bone fragment from the posterior edge of the vertebral body involved a compression of the spinal cord. A large laminectomy from L2 to T12 was immediately performed, pushing away the bone fragment, and a posterior stabilization with pedicular screws from L3 to T11. The patient recovered quickly the force of the lower limbs and his walk, but persisted a bilateral hypoesthesia in the S1 area, as well as an anesthesia S3–S4. A revalidation allowed a partial recovery of the tonicity of the anal sphincter. A urinary incontinence required self-catheterizations for a hypotonic and a reflective bladder.
The removal of the osteosynthesis pedicular screws was performed without difficulty 18 months after the traumatism. The initial approach was used, avoiding carefully the laminectomy. The disassembling and removal of the device was easy. Any immediate complication was observed. The patient recovered quickly from the pre-operative condition. The wound was perfect and dry. The urinary probe was removed according to the urologist treating the patient. But after a usual effort of miction with abdominal compression at the third post-operative day, there abruptly appeared a clear flow through the scar. A measurement of Beta-2-transferine concluded to a leakage of cerebro-spinal fluid (CSF).
Complications following lumbar spine surgery are reported to occur in 15–30% of cases . Leakage of CSF and pseudo-meningocele are common etiologies. Wang et al.  reported a rate of 14% of incidental durotomy during 641 consecutive laminectomy procedures for lumbar degenerative stenosis. They are either immediate by iatrogenic direct lesion, or late by progressive erosion of the dura on osseous tips. Moreover, any increase in the pressure of the CSF by Valsalva’s effect (cough, vomiting or post-anesthesia nausea, etc.) will tend to fissure an already weakened dura.
A midline dural tear in the spine is readily repaired; however, far-lateral or ventral dural tears are problematic. It should be repaired at the time of the original operation either directly by application of sutures or utilizing a fascia or fat graft, or a tissue-plug technique with fibrin glue [2, 6]. Some authors recommend a bed rest for nearly 7 days ; others permit to ambulate immediately after surgery . Cammisa et al.  concluded after a review of 74 dural tears that incidental durotomy, if recognized and treated appropriately, does not lead to long-term sequelae. On the other hand, Goodkin and Laska  reported that considering the frequency with which a dural tear is listed as one of the complaints in medical malpractice cases involving surgery of the lumbar spine, it cannot be considered an entirely “benign event”.
Direct dural tears can also occur for vertebral traumatisms, mainly for “burst” fracture by axial trauma [5, 12]. The dura will be then wounded either by an osseous fragment expelled in the medullar canal, or at the time of the reduction repositioning this one. Keenen  reported a 7.7% incidence of dural tears in surgically treated patients with lumbar burst fractures. Eighty-six percent of them had a neurological deficit. So he recommended exposing the dura for an initial inspection before any reduction maneuver when surgically treating lumbar burst fractures with a neural deficit.
The use of pedicular screw is currently admitted as useful in spinal surgery, mainly for the correction and the fixation of vertebral fractures [10, 19]. Combined distraction with extension during fixation using pedicular screws was found to decompress the canal and inter-vertebral foramens in a burst fracture . Transpedicular instrumentation provides rigid fixation and produces pain free fusion results. Several authors consider that pedicle screw fixation has an acceptable rate of complication and neurological injury [4, 16, 19]. Nevertheless, the use of pedicle screws even by experienced surgeons carries some risk for misplacement and neurological damage. Correct placement of transpedicular screws seems to be more difficult than it looks [8, 17]. A computer-assisted technique is much more accurate and safe than manual insertion. It can decrease the incidence of incorrectly positioned pedicle screws [1, 13]. However, neurological symptoms are not constant in the event of misplacement, as in the reported case. Only at the time of removal of the screw there appeared leakage of CSF, revealing the initial misplacement.
The diagnosis of dural tears is essential because of the infectious risk (meningitis, etc.) if a flow through the scar occurs. The clinical symptoms are the headaches in station reduced in lying position, the pain and stiffness of the neck, nausea and vomiting, photophobia and visual troubles.
A flow through the scar must be conducted to measure the beta 2 transferrine, which is a specific test for the CSF. It is a protein produced by the neuraminidase of the cerebral tissues. It is present exclusively in the CSF and the lymph.
The imagery also helps to the diagnosis. The magnetic resonance imaging allows the visualization of pseudo-meningoceles. The CT-scan will be less powerful, except if it is associated to the myelography. Afterwards, it allows the localization of the tear in order to direct the repairing surgical procedure .
The case reported here highlights also the inherent risk of the removal of pedicular screws. Lesions of the neurological structures can indeed occur at this time in the event of ignored misplacement. This gesture is thus not benign and may be complicated by potential after-effect. Moreover, if a screw appears misplaced inducing neurologic symptoms, the removal must be performed under direct vision of the dura and the nerve roots.
Incidental durotomy is not rare in spinal surgery. Penetration of the dura and injury to the neural elements can occur when pedicle screw instrumentation is used. Removal of the screw under these circumstances may cause additional complications or neurologic injury.
- 16.Schulze CJ, Munzinger E, Weber U (1998) Clinical relevance of accuracy of pedicle screw placement. A computed tomographic-supported analysis. Spine 23(20):2215–2220; discussion 2220–2221Google Scholar