Image guided lumbar nerve root sleeve injection

Authors: Prof Mark Khangure*
                            Dr Jason Wenderoth *

What are the generally accepted indications for a lumbar nerve root sleeve injection?

• Radicular leg pain with good clinical localisation and imaging confirmation.
• No acute motor weakness. Patients with long-standing weakness, and radicular pain, may be considered for this procedure.
• Imaging showing root compromise in the foramen or lateral recess.
• Awaiting surgery to decompress the nerve (e.g. foraminotomy, laminectomy/discectomy).
• Patients wishing to avoid surgery and wanting less-invasive management.
• Post-discectomy radicular pain attributed to scar tissue or oedema.
• Diagnostic test to confirm the level of symptomatic root compression before surgery when multiple foraminal narrowing is present.

What are the prerequisites for having a lumbar nerve root sleeve injection done?

• Clinical localisation of pain to a particular root, or no more than 2 roots (diagnostic block).
• Imaging correlation of the clinical findings with CT or magnetic resonance imaging.
• No muscle weakness or features of cauda equina syndrome.

What are the absolute contraindications for a lumbar nerve root sleeve injection?

• Severe bleeding disorder and excessive anticoagulation. Warfarinised patients will need to have an INR 1.5 or less for the procedure to be carried out safely. Antiplatelet agents may need to be ceased for up to 10 days depending on the preference of the radiologist carrying out the procedure. Aspirin is generally not discontinued before the procedure.
• Symptoms of cord compression or cauda equina syndrome.
• Acute motor weakness from a known disc protrusion. Acute nerve root compression with motor weakness may result in root ischaemia and permanent damage if the nerve root is not decompressed, so surgery rather than nerve root injection is the preferred treatment for acute motor weakness resulting from lumbar nerve root compression.
• Known disc or epidural infection.

What are the relative contraindications for a lumbar nerve root sleeve injection?

Diabetes (because root sleeve injections usually include corticosteroids, diabetic control may be temporarily affected), local skin infection, uncompliant patient and unwell patient.

What are the adverse effects of a lumbar nerve root sleeve injection?

Immediate:

• Bleeding leading to further root compression.
• Increase in pain, particularly when a large foraminal disc protrusion is present before the anaesthetic block.
• Extreme pain from direct injection into the nerve root.
• Syncope from a vasovagal response.
• Rapid spinal block, from inadvertent intrathecal injection of the local anaesthetic.
• Rarely, paraplegia can ensue when the artery of Adamkiewicz enters a lumbar neural foramen and is inadvertently injected. This seems to occur more often when particulate corticosteroids (e.g. DepoMedrol) are used and contrast is not injected to ensure that intravascular injection is not occurring. CT or digital subtraction angiography equipment are probably better than standard fluoroscopic equipment for ensuring that vascular injection is avoided.

In view of these adverse effects, it is preferable that these procedures be performed in clinics in or close to hospital.

Delayed:

Headache, infection, root ischemia if direct root injection, leading to both a motor deficit and pain. Avoided with CT imaging and good technique.

Adverse events are very rare in experienced hands, particularly with CT guidance and attention to detail.

There are several severe and immediate but rare complications including:

• posterior circulation stroke;
• paraparesis – temporary (as a result of a inadvertent epidural injection) or permanent;
• anaphylaxis.

Is there any specific post procedural care required following a lumbar nerve root sleeve injection?

• Avoidance of strenuous activity for a couple of days.
• Driving should be avoided on the day of the procedure (it is advisable to have someone drive the patient to and from the practice).
• Patients are advised to continue any regular pain relief medications they are taking, particularly for the first 24 hours post-procedure, because the injection may in fact exacerbate symptoms during this period. After that, they are advised to wean off any medications they are on, tapering to zero on day 4–5 post-injection to assess the effect of the injection. If they are not on any medication at the time of the procedure, they are advised them to take 1 g paracetamol every 6 hours for 24 hours post-procedure, then as needed according to the directions on the packaging thereafter.
• In general, anticoagulant drugs may be started the day following the procedure, but it is advised to check this with the radiologist on the day of the procedure.

Are there alternative imaging tests, interventions or surgical procedures to a lumbar nerve root sleeve injection?

Surgical decompression of the nerve root.

Useful websites about lumbar nerve root sleeve injection

Selective Nerve Root Blocks for the Treatment of Sciatica: Evaluation of Injected Site and Effectiveness – A Study with Patients and Cadavers.
pubs.rsna.org/doi/full/10.1148/radiol.2213001635

*The author has no conflict of interest with this topic.

Page last modified on 26/7/2017.