In our daily practise we manage to perform all thoraco-lumbar vertebral procedures with three main vertebral accesses:

1. Transpedicular: a safe access that should be chosen when pedicles allow a proper positioning in the vertebral body, mainly in lumbar vertebrae. In lumbar vertebrae, the junction between the transverse process and the superior articular process is usually a good vertebral entry point (Fig. 1).

2. Intercosto-vertebral (or parapedicular): in thoracic vertebrae, an access through the costo-vertebral joint passing cranially to the transverse process (with more possibility of redirectioning the trocar) (Fig. 2) or passing all along the intercosto-transverse joint if its orientation is suitable (with less possibility of redirectioning the trocar). In some cases an intercosto-vertebral access passing through the transverse process may be performed, with little possibility of trocar redirectioning (Fig. 3). The intercosto-vertebral access can be used in the presence of orthopaedic hardware (Fig. 4).

3. Extra-pedicular: in lumbar vertebrae, an access on the posterior margin of lateral vertebral face, just anterior to the pedicle, this access may be used when pedicles are too narrow and straight to allow a proper positioning (Fig. 5) or in the presence of pedicular orthopaedic hardware (Fig. 6). It should be chosen as second choice, due to its slightly higher risk of lesions of lumbar arteries [2]. Since most of the lumbar segmental arteries pass in the inferior portion of pedicles, the extra-pedicular access should be slightly higher than the sagittal midline of the pedicle to avoid arterial injury [3].

These are the main steps for vertebral access in our daily practice (Fig 7):

• first CT scan, choice of vertebral target, vertebral access point and cutaneous entry point;

• positioning of a 20 gauge Chiba needle up to periosteum for periosteal block;

• removal of Chiba needle head and sliding of hollow 13 gauge trocar on it;

• progression of trocar in the vertebral body.

Needle and trocar are advanced under fluoroscopic guidance in lateral projection and controlled with repeated thin CT scans. The initial positioning of a 20 gauge Chiba needle is a safe technique, since this needle is scarcely traumatic and can be safely repositioned if necessary: once it is in the right position, the hollow 13 gauge trocar may be securely slided on it, with no need of further repositioning. This technique is particularly useful in intercosto-vertebral access, where the Chiba needle gets secured in the intercosto-vertebral joint (Fig. 2).

We always try to find an access on axial plan, since it’s easier to visualize the entire needle on intra-procedural CT scans. It’s fundamental to clearly visualize the trocar tip at CT scan controls. Sometimes thoracic vertebrae require a caudo-cranial oblique trocar pathway due to dorsal kyphosis: in such cases, using the intercosto-vertebral access, the trocar can be advanced axially up to the vertebral cortex and once the tip enters the vertebral body, it can be easily redirected cranially or caudally as requested, by gently pushing it against the soft tissues. 

If the required trocar pathway is too oblique and an axial access is not possible, thicker CT spirals may be needed to better visualize the trocar positioning with multiplanar reconstructions. As an alternative, some CT gantries may be tilted back or forward for a modified axial plane.

We look in first place for a transpedicular access in lumbar vertebrae and for an intercosto-vertebral access in thoracic ones, since they fit better to vertebral anatomy.