Ultrasound guided caudal epidural injections in the management of disc-related sciatica: Audit data from a Spinal Interface Service

Purpose

Epidural injections are recommended by NICE guidelines and commonly used for treating disc-related sciatica, as they might provide substantial pain relief and reduce the need for spinal surgery. They are delivered via one of three lumbar spinal routes: transforaminal (TF), interlaminar (IL), or caudal (C).

In the UK, the most common epidural routes for disc-related sciatica are the TF and C routes, with almost equal numbers of each in recent years, indicating clinical practice variation. TF epidurals are considered, by some, to be clinically more effective than C epidurals, as in theory they are more target-specific.

They are however, technically demanding, require a specialist setting, with often long waiting lists, and exposure to ionising radiation. C epidurals are considered less targeted, easier to perform and overall safer. There is no convincing evidence that TF epidurals are superior. C epidurals may require no exposure to radiation, as ultrasound scan (USS) can be used, they can be delivered in less specialist settings, and are less costly.

Our Spinal Interface Service functions as the 'gatekeeper' for referrals to secondary care, spinal ESPs assess in excess of 7.000 patients a year and we offer USS guided C epidural injections to well-selected patients. The injections are delivered by an appropriately trained ESP, the service is medically supported by a Rheumatology Consultant.

This clinical audit investigated the outcomes of USS guided C epidurals for disc-related sciatica, delivered in our day-case unit.

Outcomes for the 73 who received the injection were as follows;
34% made no further contact with the service (n=25)
18%
''significantly'' improved (n=13)
27%
no better/worse (n=20)
21%
''minor'' or short term (1-3 weeks) improvements (n=15)
...52%
of patients reporting improvement or seeking no further contact with the service, which is used as a proxy for improvement.

Approach

Retrospective audit of all patients referred for USS C epidural from January 2017 to December 2017.

To be listed for the injection, all patients had to have predominately leg pain, an MRI scan confirming nerve root compression at L4/5 or L5/S1 by central / paracentral disc prolapse, and clinically concordant findings.

Injection outcome data or further clinical contact data, were extracted from subsequent clinical letters and from hospital appointment records.

Outcomes

A total of 101 patients were referred for C epidural. Of those, 28 did not proceed with the injection; main reasons being improvement in leg pain or predominately having low back pain.

Outcomes for the 73 who received the injection were as follows;

  • 34% made no further contact with the service (n=25)
  • 18% ''significantly'' improved (n=13)
  • 21% ''minor'' or short term (1-3 weeks) improvements (n=15)
  • 27% no better/worse (n=20)

Average waiting time for the injection was about 3 weeks. No serious side effects were recorded.


USS guided caudal epidurals, performed by an ESP within a Spinal Interface Service, are safe and potentially useful for disc-related sciatica, with 52% of patients reporting improvement or seeking no further contact with the service, which is used as a proxy for improvement.

Implications

The results of this audit support the use of USS guided caudal epidurals in a well-supported setting outside secondary care, for the management of disc-related sciatica in appropriately selected patients.

However, appropriately designed research is needed to provide definitive evidence as to whether this safe and low cost procedure is equally effective with the more targeted injection approaches.

Funding acknowledgements

No funding was received.

Additional notes

This work was presented at Physiotherapy UK 2019