Gianluigi Guarnieri

Biomechanics of the spine. Part I: Spinal stability

Biomechanics, the application of mechanical principles to living organisms, helps us to understand how all the bony and soft spinal components contribute individually and together to ensure spinal stability, and how traumas, tumours and degenerative disorders exert destabilizing effects. Spine stability is the basic requirement to protect nervous structures and prevent the early mechanical deterioration of spinal components. The literature reports a number of biomechanical and clinical definitions of spinal stability, but a consensus definition is lacking. Any vertebra in each spinal motion segment, the smallest functional unit of the spine, can perform various combinations of the main and coupled movements during which a number of bony and soft restraints maintain spine stability. Bones, disks and ligaments contribute by playing a structural role and by acting as transducers through their mechanoreceptors. Mechanoreceptors send proprioceptive impulses to the central nervous system which coordinates muscle tone, movement and reflexes. Damage to any spinal structure gives rise to some degree of instability. Instability is classically considered as a global increase in the movements associated with the occurrence of back and/or nerve root pain. The assessment of spinal instability remains a major challenge for diagnostic imaging experts. Knowledge of biomechanics is essential in view of the increasing involvement of radiologists and neuroradiologists in spinal interventional procedures and the ongoing development of new techniques and devices. Bioengineers and surgeons are currently focusing on mobile stabilization systems. These systems represent a new frontier in the treatment of painful degenerative spine and aim to neutralize noxious forces, restore the normal function of spinal segments and protect the adjacent segments. This review discusses the current concepts of spine stability.

Role of computed tomography in the assessment of intraorbital foreign bodies.

Intraorbital foreign bodies (IOFBs) are a common occurrence worldwide and happen at a frequency of once in every 6 cases of orbital trauma. An orbital foreign body may produce a variety of signs and symptoms related to its size, composition, and ballistics. Retained foreign bodies may give rise to cellulitis, abscess, fistulas, and impaired vision and motility. Prompt detection and accurate localization of IOFBs are essential for the optimum management of patients, to enable the surgeon to plan the most atraumatic method of removing the IOFB. Computed tomography (CT) is very useful in determining the size of foreign bodies and localizing them as intraocular, extraocular, or retro-ocular. CT is generally considered the gold standard in the evaluation of IOFBs because it is safe to use with metallic IOFBs, excludes orbitocranial extension, and is also able to diagnose orbital wall fractures and orbital sepsis with high accuracy. Other potential complications excludible by CT are abscess formation in the orbit, bone, and brain. Magnetic resonance imaging is generally not recommended for the evaluation of the foreign bodies because of risks associated with magnetic metal.

A comparison of minimally invasive techniques in percutaneous treatment of lumbar herniated discs. A review.

Low back pain is the commonest spine disease causing absence from work in developed countries. Low back pain with classical irradiation along the course of the nerve root affected is more frequently due to disc disease. In 60–80% of patients with herniated disc, radicular symptoms disappear with conservative treatment after about six weeks, the remainder are treated surgically with a 2–6% of incidence of true recurrence of herniation post-intervention and with failed back surgery syndrome in 15% of cases. Recently minimally invasive techniques have developed as “alternative” treatments to surgical intervention. This review aimed to assess the pathogenesis of low back pain caused by lumbar disc hernia as a basis for action of minimally invasive techniques; to illustrate the techniques already used or currently in use, to compare them in technical guidance, indications and complications, exposing for each of them the inclusion/exclusion criteria in enrolling patients and the imaging guide technique of choice. Minimally invasive techniques can be a valuable alternative to traditional surgery with low cost, low risk of complications, easy feasibility, and in the event of failure they do not exclude subsequent surgery.

Assisted techniques for vertebral cementoplasty: Why should we do it?

Assisted techniques (AT) for vertebral cementoplasty include multiple mini-invasive percutaneous systems in which vertebral augmentation is obtained through mechanical devices with the aim to reach the best vertebral height restoration. As an evolution of the vertebroplasty, the rationale of the AT-treatment is to combine the analgesic and stability effect of cement injection with the restoration of a physiological height for the collapsed vertebral body. Reduction of the vertebral body kyphotic deformity, considering the target of normal spine biomechanics, could improve all systemic potential complications evident in patient with vertebral compression fracture (VCF). Main indications for AT are related to fractures in fragile vertebral osseous matrix and non-osteoporotic vertebral lesions due to spine metastasis or trauma. Many companies developed different systems for AT having the same target but different working cannula, different vertebral height restoration system and costs. Aim of this review is to discuss about vertebral cementoplasty procedures and techniques, considering patient inclusion and exclusion criteria as well as all related minor and/or major interventional complications.

Endovascular strategy for unruptured cerebral aneurysms

The treatment of unruptured intracranial aneurysms (UIAs) remains complex and not clearly defined. While for ruptured intracranial aneurysms the management and the treatment option (surgery or endovascular treatment) are well defined by several trials, for asymptomatic UIAs the best management is still currently uncertain. The rationale to treat an UIA is to prevent the rupture and its consequent SAH and all complications derived from hemorrhage or reduce/eliminate neurological palsy. Although this statement is correct, the indication to treat an UIA should be based on a correct balance between the natural history of UIA and treatment risk. Patients clinical history, aneurysm characteristics, and strategy management influence the natural history of UIAs and treatment outcomes. In the last 10 years and more, two important large multicenter studies were performed in order to analysis of all these factors and to evaluate the best treatment option for UIAs. The aim of this paper is to try to synthesize the possible indications to the endovascular treatment (EVT), when and how to treat an UIA.

Combined Percutaneous and Endovascular Treatment of Symptomatic Aneurysmal Bone Cyst of the Spine: Clinical Six Months. Follow-up of Six Cases.

We describe the usefulness of endovascular and direct percutaneous treatment as a therapy option for aneurysmal bone cysts (ABCs) of the spine. From January 2007 to December 2008, we treated six consecutive patients with symptomatic ABCs resistant to continuous medical management or with acute clinical onset of paraparesis at cervical, thoracic and lumbar spine level. Two patients were treated after emergency laminectomy. All patients were studied with an MRI protocol and multidetector CT with MPR reconstructions followed by angiographic control before treatment. The procedure was performed under general anaesthesia for all patients. Under CT or fluoroscopy guidance, percutaneous treatment was performed either by direct injection of Glubran® diluted at 30% with Lipiodol® only, or combined with endovascular treatment by Onyx® injection. Clinical and X-ray follow-up was performed at three and six months. Combined endovascular and percutaneous treatment for ABCs was successful and led to an excellent outcome in five out of six patients with clinical improvement. There were no periprocedural or subsequent clinical complications and the glue resulted in successful selective permanent occlusion with intralesional penetration. Direct sclerotherapy resulted in immediate thrombosis of the malformation with no progression of symptoms. Complete healing was observed in five out of six aggressive lesions. No major complications were noted. At six month follow-up the symptoms had completely resolved and X-ray control showed a partial or total sclerotic reaction of the lesion with stable clinical results (no partial or clinical abnormalities). One patient had a recurrence of the ABC with spinal cord cervical clinical symptomatology. Combined endovascular and percutaneous treatment or direct percutaneous sclerotherapy with glue alone are important, safe, effective therapy options for symptomatic aneurysmal bone cyst. Results are stable and confirmed by clinical and X-ray follow-up six months after treatment.

Vertebral Body Stenting System for the Treatment of Osteoporotic Vertebral Compression Fracture: Follow-up at 12 Months in 20 Cases.

We describe our preliminary experience with the vertebral body stenting system (VBS) for the treatment of osteoporotic vertebral fracture or traumatic vertebral fracture showing our clinical results at 12 months follow-up. Twenty patients (16 women, four men, mean age 71 years): four with traumatic vertebral fracture (Magerl A1 fractures) and 16 with osteoporotic vertebral compression fracture (VCFs) resistant to conservative therapy, were treated by vertebral body stenting system (VBS) as follows: two at level T11, four at T12, one at L1, two at L2, five at L3 and six at L4. All patients were studied by MR (protocol: sagittal T1W, T2W and T2 STIR) and MDCT with MPR reconstructions. All procedures were performed under local anesthesia with fluoroscopy guidance and a bipeduncular approach. VBS, a new system of implantation of endovertebral stent used as an alternative to conventional vertebroplasty (VP), was implanted in all patients to restore the loss of height in the fractured vertebral body. A clinical and x-ray follow-up was performed at six and 12 months evaluating the result by VAS and ODS scale. New vertebral fractures at a distant level were observed in two cases and treated by VP. VBS was successful and led to an excellent outcome in all patients with clinical improvement stable at six months and one year follow-up. The height in the fractured vertebral body was increased in 12 of the 20 VCFs by an average of 1.5 mm. No vascular, extraforaminal or epidural leakage or other adverse events were observed. In the clinical 12 months follow-up we recorded a reduction of four scores in the VAS evaluation and a 40% reduction in the ODS score compared with the pre-treatment values. Endovertebral stents were stable at 12 months at x-ray control in 19/20 patients. No new vertebral fracture located in adjacent vertebrae were observed at 12 month follow-up. By using a stent, the VBS system reduces the collapsed vertebral body and offers good height restoration. The mechanical scaffold of the stent restores the height and at the same time offers a cavity for injection of highly viscous PMMA bone cement without increasing the rate of new vertebral fracture post-VP. A long-term follow-up is recommended.

Vertebroplasty as a Treatment for Primary Benign or Metastatic Cervical Spine Lesions: Up to One Year of Follow-up

This paper illustrates the validity of vertebroplasty (VP) in patients with primary benign or metastatic lesion in the cervical spine. From January 2006 to December 2007, ten consecutive patients were treated with VP for a total of ten vertebral bodies: two symptomatic vertebral haemangiomas at C5 and C4.3, multiple myeloma at C2 (two cases) and one case at C4, five patients with vertebral metastasis from breast or lung cancer at C2, C4 (three cases) and C5. All the patients complained of pain resistant to continuous medical management. All procedures were performed under general anaesthesia by anterolateral approach under CT or fluoroscopy control with manual dislocation of the carotid axis. A transoral approach under fluoroscopy was performed to treat the C2 lesion. Bone biopsy was never performed. VP was performed to prevent fracture after implantation of a double discal prothesis in two patients. For patients with multiple myeloma, VP was performed to prevent new vertebral fracture. VP was performed before of radiotherapy in three patients with metastasis, and just after radiotherapy in two. Two metastatic patients were lost at one year follow-up due to death from systematic diffusion. Results were evaluated on the Visual Analogue Scale (VAS) and the Oswestry Disability Index (ODS). A successful outcome was observed with a complete resolution or partial reduction of pain in 90% of patients 24–72 hours after VP. At 12 months follow-up, we recorded a reduction of four points in the VAS evaluation and a 45% reduction in the ODS score. No extravertebral vascular or discal cement leakage was observed. At 12 months, X-ray follow-up showed a stable result. Percutaneous treatment with VP for benign or malignant cervical spine lesions is a valuable, mini-invasive and quick method that allows a complete and enduring resolution of painful vertebral symptoms without fracture of the adjacent or distal vertebral bodies.

What's new in vertebral cementoplasty?

Vertebral cementoplasty is a well-known mini-invasive treatment to obtain pain relief in patients affected by vertebral porotic fractures, primary or secondary spine lesions and spine trauma through intrametameric cement injection. Two major categories of treatment are included within the term vertebral cementoplasty: the first is vertebroplasty in which a simple cement injection in the vertebral body is performed; the second is assisted technique in which a device is positioned inside the metamer before the cement injection to restore vertebral height and allow a better cement distribution, reducing the kyphotic deformity of the spine, trying to obtain an almost normal spine biomechanics. We will describe the most advanced techniques and indications of vertebral cementoplasty, having recently expanded the field of applications to not only patients with porotic fractures but also spine tumours and trauma.

Update of vertebral cementoplasty in porotic patients.

Vertebroplasty (VP) is a percutaneous mini-invasive technique developed in the late 1980s as antalgic and stabilizing treatment in patients affected by symptomatic vertebral fracture due to porotic disease, traumatic injury and primary or secondary vertebral spine tumors. The technique consists of a simple metameric injection of an inert cement (poly-methyl-methacrylate, PMMA), through a needle by trans-peduncular, parapeduncular or trans-somatic approach obtaining a vertebral augmentation and stabilization effect associated with pain relief. The technique is simple and fast, and should be performed under fluoroscopy or CT guidance in order to obtain a good result with low complication rate. The aim of this paper is to illustrate the utility of VP, the indications-contraindications criteria, how to technically perform the technique using imaging guidance, and the results and complications of this treatment in patients affected by symptomatic vertebral compression fracture.