Minimally Invasive Disk Interventions



Minimally Invasive Disk Interventions


Gianluigi Guarnieri, Fabio Zeccolini and Mario Muto



Introduction


When medical treatment has been unsuccessful for patients with low back pain (LBP) due to a small or contained herniated disk, minimally invasive techniques have recently been developed as “alternative” treatments to surgical intervention. Outcomes of these alternative treatments depend on the characteristics of the herniation itself and on the chosen technique.1 Techniques include:



All techniques can be performed under computed tomography (CT) or fluoroscopic guidance with the patient in prone position and under local anesthesia.2 They offer good results, good patient compliance, low cost, and low complication rates. Patients need a short period of hospitalization, but most procedures can be performed in day surgery, and in cases of failed treatment, all techniques can be repeated once without interfering with surgery at a later date. All procedures can be performed at either cervical or lumbar levels. The rationale of all percutaneous treatments is to reduce the intradiscal pressure in different ways, creating the space required to decompress retropulsion or mass affect of the disk.



Pathogenesis of Low Back Pain


The pathogenesis of LBP is due to multifactorial mechanisms, but the two most common are mechanical causes that result in nerve root compression and acute inflammatory factors.





Indications and Contraindications


General Exclusion Criteria




The last three conditions are absolute indications for surgery. The best results are reported for small and medium-sized herniations within a normal spinal canal and without disk calcifications. Prognostic factors for an unsuccessful outcome are presence of a calcified herniated disk, high-grade spinal stenosis, a small descending herniated disk in the lateral spinal recess, failed back syndrome, and recurrent disk herniation.



General Inclusion Criteria




• Clinical criteria: LBP and sciatica resistant to conservative medical therapy, physiotherapy, and other interventions for a period not shorter than 2 to 3 months


• Neurologic criteria: paresthesia or altered sensitivity over the dermatome involved, mild muscle weakness, and signs of root ganglion irritation


• Psychological criteria: a firm resolve on the part of the patient to recover, with a commitment to cooperate and undergo subsequent physiotherapy with postural and motor rehabilitation


• Neuroradiology (CT, MRI):





Technique


The following are minimally invasive percutaneous techniques used in clinical practice to treat herniated lumbar disks.



Automated Percutaneous Lumbar Discectomy


APLD uses an instrument called a nucleotome, consisting of a compressed-air pneumatic pump connected to an “aspirating-cutting” probe with an external diameter of 2 mm. The probe is introduced into the disk through a 2.5-mm-diameter needle under fluoroscopic guidance. The nucleus pulposus is aspirated through a lateral window of the probe while a blade that moves coaxially within the probe destroys it and allows it to be drained.


This technique is indicated for all types and locations of disk protrusions or herniations without extrusion or free fragments. The success rate is about 70% to 80%. If the exclusion criteria are not considered, the success rate drops to 49.4%. When the procedure is not performed correctly, it may damage nerve roots or dural tissue. The most serious complication reported with this procedure is cauda equina syndrome, characterized by saddle anesthesia of the perineal region, retention or urine/fecal incontinence, and bilateral hyposthenia.3-5



Percutaneous Laser Disk Decompression


PLDD consists of introducing a soft flexible needle (0.8 mm) under fluoroscopic guidance into the nucleus pulposus of the herniated disk. Once the correct position of the needle is confirmed, a thin optical fiber connected to an Nd:YAG laser is introduced. The Nd:YAG is a special laser that works with a solid energy source, a yttrium aluminium garnet crystal doped with neodymium.


The action is based on the idea that the vertebral disk is a closed hydraulic system composed of the nucleus pulposus, made of water, surrounded by the fibrous annulus. An increasing water content of the nucleus pulposus causes a disproportionate increase of intradiscal pressure. Vaporizing the nucleus pulposus leads to a reduction of intradiscal pressure and facilitates a relocation of the extruded nucleus pulposus into its original position. The laser vaporizes water in the nucleus pulposus, allowing decompression of disk pressure on the nerve root, with resolution of symptoms. It can be performed under CT or fluoroscopy guidance. If the hernia is contained, it is possible to perform PLDD under fluoroscopic guidance, releasing laser energy at the vertebral disk’s center and posterior portion.


If the disk herniation is not contained but still connected to the intervertebral disk, it is better to perform the decompression procedure under CT guidance to better assess the connection of the disk and hernia portions. In this way, the laser energy can be released in multiple locations of the herniated disk, obtaining better vaporization and retraction of the hernia, with resultant root decompression and resolution of symptoms. The outcomes reported are success rates between 75% and 87% of cases, with an immediate reduction of back pain in 48% of cases. Septic and aseptic diskitis are the most common complications, with an average occurrence of 0% to 1.2% of cases. Septic diskitis is caused by introduction of microorganisms during positioning of the needle into the disk. Sterile technique is required. Aseptic diskitis is caused by the action of the laser itself on the disk and the adjacent vertebral plate.6-12


Uncommon complications such as intestinal perforation, cauda equina syndrome, and nerve root lesions with consequent impairments have been reported.



Intradiscal Electrothermal Therapy


IDET acts on the posterior aspect of the fibrous annulus, unlike other techniques where the action is on the nucleus pulposus. Under fluoroscopic guidance, a trocar is introduced into the intervertebral disk, then an electrothermal flexible catheter is introduced between the nucleus pulposus and annulus. The tip of the catheter has a resistor that, once placed near the posterior margin of the annulus, is warmed to 90°C for 16 to 17 minutes and then removed (Fig. 161-1). Warming the fibrous annulus reduces symptoms and stabilizes the disk lesion by reorganizing collagen fibers, strengthening the disk, cauterizing ring fissures, and ablating pain receptors.



IDET is indicated for treatment of a bulging disk or contained herniated disk without root compression symptoms and resistance to pharmacologic therapy and physiotherapy for more than 6 months. To obtain a better evaluation of a contained hernia, disk compression, or disk pressure, a previous diskography may be needed. The complication rate is 0.8%, with high frequency of osteonecrosis post IDET. The success rate is between 40% and 71% of cases.12-17


Dec 23, 2015 | Posted by in INTERVENTIONAL RADIOLOGY | Comments Off on Minimally Invasive Disk Interventions
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