Pain Blocks (including nerve root blocks)

Pain blocks are usually performed under fluoroscopic or CT guidance and occasionally with ultrasound. Patients with pain due to inflammation in a ligament or joint or irritation of a nerve root can benefit from this procedure. A facet block is a specific type of pain block targeting inflamed facet joints in the spine. Facet joints are joints in the spine that lie behind the main body of the vertebrae. Other joints that can be treated include the shoulder, sacroiliac and hip joints. Patients with inflammation in the foot (plantar fasciitis) can be similarly treated. Local anaesthetic is infiltrated into the skin at the site of puncture. A small gauge needle is inserted into the painful joint or adjacent to the irritated nerve. A combination of a local anaesthetic and a long acting steroid with anti-inflammatory properties is injected to relieve the pain. In the case of a 'frozen shoulder', the distention of the joint due to the injection is thought to assist in improving joint mobility. The image to the right is an example of CT guided needle placement for a pain block.

Preparation: A consent form is required. There is no specific preparation.


Drainage procedures

Under imaging guidance and using either CT or Ultrasound, this technique involves the percutaneous drainage of fluid collections usually from the thorax, abdomen or pelvis or from cysts in the kidney, liver, breast etc. 'Percutaneous' means via a puncture through the skin. After injection of local anaesthetic into the skin, a small to medium gauge needle is inserted into the cyst or collection under aseptic conditions. In some cases the cyst or collection is simply drained by aspiration through this needle as in the drainage of breast cysts. In large infected collections particularly in the abdomen or pelvis, a flexible 'pigtail' catheter may be inserted into the collection using guidewires and dilators to assist in the placement of the catheter. This catheter is left in place and attached to a drainage bag to enable complete resolution of the collection. Material obtained from the aspiration is sent for pathology tests to identify infecting organisms or sometimes to check for abnormal cells. Some large cysts of the kidney may be treated with an alcohol injection after the drainage. The alcohol irritates the cyst lining and helps prevent recurrence.
A nephrostomy is a special type of drainage procedure which involves the insertion of a 'pigtail' catheter into the collecting system of a kidney to relieve an obstruction. A needle is inserted into the dilated kidney and the position confirmed. A guide wire is inserted into the kidney and dilators used to enlarge the tract. The pigtail catheter is inserted over the guidewire and secured in place. A drainage bag is connected to the catheter.

Preparation: A consent form is required. There is no specific preparation.

Vascular interventional procedures

Angioplasty: A special catheter with a small balloon attached is placed into the narrowed area of an artery called a stenosis. The balloon is inflated in order to expand the stenosis. The result is improved blood flow through the artery. This technique is most commonly used for narrowings in the arteries of the legs. Stenoses of the renal arteries supplying the kidneys can also be treated. Please refer to diagram below.

Stents: A small expandable stent made from metallic mesh is attached to the end of a catheter and guided to the site of a narrowing in an artery. The stent is detached and expands within the artery resulting in dilatation of the narrowing. The result is improved blood flow through the artery. Stenting helps prevent a recurrence of the narrowing at a later stage. Please refer to diagram below. The picture to the right is an example of an expanded stent.

Thrombolysis: A small catheter is placed near a blockage of an artery and concentrated blood thinners are delivered to the site via a slow infusion. This is performed in an attempt to dissolve the clot blocking the artery to improve blood flow.

Embolisations: In this procedure, a selected artery is blocked using small detachable balloons, wire coils or chemical agents in order to interrupt the blood supply of a region. The technique is used to stop bleeding from an artery following trauma, to reduce the blood supply of a vascular tumour prior to surgery or to treat vascular malformations or aneurysms.

Preparation: All patients undergoing vascular procedures are fully informed of the details of the procedure prior to signing a consent form. The attending nurse contacts patients the night before the examination to discuss the preparation and to ask relevant questions. Blood tests may be required to check for normal clotting times. A light diet and fluids are permitted on the morning of the procedure. Patients taking blood thinning medication or diabetic medication require specific preparation instructions. A history of allergies is obtained.




Safety Issues

With any procedure there are possible complications however these tend to be minor in most instances. In angiography the main complications are related to injury or blockage of an artery either at the puncture site or in the region of interest. Also bleeding may occur at the puncture site and occasionally a focal dilatation called a false aneurysm may form where the catheter entered the artery. Safety concerns regarding Contrast and X-rays in general are discussed at our Safety Issues webpage.

Click here for frequently asked questions in interventional radiology.