Next Level in Computed Tomography-Guided Periradicular Infiltration Therapy: Same Efficiency with Less Radiation Exposure

OBJECTIVE

This retrospective cohort study investigated the radiation exposure and clinical efficiency of a new institutional low-dose protocol for computed tomography (CT)-guided lumbar periradicular infiltration (PRI).

METHODS

This was a retrospective matched-pair comparison of patients undergoing single-level lumbar PRI therapy employing a new low-dose CT protocol consisting of a helical scan with reduced energy levels and tube current versus the institutional standard CT protocol. The following variables were collected: dose-length product for the planning step, interventional step, and total examination, number of CT guidance scans, examination time, and postprocedural improvement on the numerical rating scale for radicular pain.

RESULTS

Forty-five patients were allocated to each group. A sufficient radiation dose reduction of 30% during PRI was achieved with the low-dose protocol with a median dose-length product of 9.8 mGy∗cm compared to 32.9 mGy∗cm with the standard protocol (P < 0.001). No need for additional multiple scans during the interventional mode was observed in the low-dose group, resulting in a comparable procedure time between the groups. Furthermore, the short-term pain-reducing effect of PRI was comparable between the low-dose and standard protocols (median delta numerical rating scale = 4 in both groups).

CONCLUSIONS

Our low-dose protocol with less tube voltage and lower electric current leads to less radiation exposure with the same safety and efficiency. In conclusion, every facility that performs CT-based procedures should check whether a further dose reduction is applicable to avoid stochastic radiation damage to the patient.

The role of periradicular infiltration in dorsal root ganglion stimulation for chronic neuropathic pain

Background

Targeting the correct spinal level is essential in dorsal root ganglion (DRG) stimulation. Anatomical selection of the DRG alone is not ideal since the pain area is not necessarily confined to the borders of the dermatomes. This study aims to establish the role of periradicular infiltration therapy (PRT) in the preoperative assessment of the correct level for DRG stimulation performed under general anesthesia.

Method

We report a prospective study of 20 patients selected for DRG stimulation and submitted to a PRT for identification of the spinal level. Lead implantation for the stimulation trial occurred under general anesthesia: 19 patients experienced positive results and underwent implantation of the pulse generator. All patients suffered from chronic neuropathic pain unresponsive to best medical treatment. PRT levels were compared with the levels targeted with DRG leads. Patients were followed for up to 12 months; pain intensity and coverage of the painful area were assessed.

Results

In 12 patients, the trial leads were placed on the same level as previously tested positive by PRT. In 6 patients, leads were placed in the PRT target and additionally in adjacent spinal levels. In one case, the selected target for the trial diverged from the PRT target because of intense fibrosis in the chosen level. Coverage of the target area of at least 50% was achieved by two-thirds of the patients. For the six subjects with additional implanted leads as a consequence of the PRT results, 80% achieved a coverage of at least 50%. A total of 47.4% of the patients achieved sustained significant pain relief in the last follow-up. None of the patients needed a repeated surgery for implantation of additional leads.

Conclusions

PRT is a helpful tool to confirm the stimulation targets. A PRT preceding the stimulation trial is an additional opportunity to optimize the coverage of the target area with stimulation-induced paresthesia for patients operated under general anesthesia.

Severity of foraminal lumbar stenosis and the relation to clinical symptoms and response to periradicular infiltration-introduction of the "melting sign"

BACKGROUND CONTEXT

Nerve root compression causing symptomatic radiculopathy can occur within the intervertebral foramen. Sagittal magnetic resonance imaging (MRI) sequences are reliable in detection of nerve root contact to intraforaminal disc material, but a clinically relevant classification of degree of contact is lacking.

PURPOSE

This study aimed to investigate a potential relation of amount of contact between intraforaminal disc material and nerve root to clinical findings and response after periradicular corticosteroid infiltration.

STUDY DESIGN

A post hoc analysis of a prospective cohort was carried out.

PATIENT SAMPLE

Patients who underwent computed tomography (CT)-guided periradicular corticosteroid infiltration (L1-L5) at our institution (January 2014 to May 2016) were included.

OUTCOME MEASURES

The medical records and radiographic imaging were reviewed.

METHODS

T2-weighted MRI of the lumbar spine of patients with single-level symptomatic radiculopathy with (responders, n=28) or without (non-responders, n=14) pain relief after periradicular infiltration with corticosteroids were measured and compared by two independent readers to determine the amount of intraforaminal nerve root contact with the intervertebral disc ("melting" of the T2-hypointense signal). Pain relief was defined with a pain level decrease of >50% on a visual analogue scale and lack of pain relief with a pain level decrease of <25%, respectively. The amount of T2-hypointensity melting of disc and nerve root was categorized to 0%, 1%-25%, and over 25%.

RESULTS

Reader one identified 0% T2-melting in none of the responders, 1%-25% melting in 13 patients (46.4%), 26%-50% in 15 of the 28 patients (53.6%) with pain relief after periradicular corticosteroid infiltration (responders), with a mean amount of T2-melting of 5.9±2.1 mm, whereas the non-responder group had 0% T2-melting in 2 patients (14.3%), 1%-25% T2-melting in 11 patients (78.6%), and 26%-50% in 1 patient (7.1%), with a mean amount of T2-melting of 2.6±1.9 mm (p<.05). Reader two identified 0% T2-melting in none, 1%-25% T2-melting in 15 (53.6%) patients, and 26%-50% in 13 of the 28 responders (46.4%), with mean amount of 6.3±1.9 mm. In the non-responder group 0% T2-melting was seen in 3 patients (21.4%), 1%-25% T2-melting in 10 patients (71.4%), and 26%-50% in 1 patient (7.1%), with a mean amount of T2-melting of 2.7±1.9 mm (p<.05). None of the MRI showed T2-melting in over 50% of the circumference of the intraforaminal nerve root. A T2-melting of >25% had a high specificity of 93% but a sensitivity of 50%, thus a positive likelihood ratio of 7.5, to identify those with a pain relief of more than 50% after infiltration.

CONCLUSION

The amount of T2-melting of disc material and nerve root on sagittal MRI (>25%) predicts the amount of pain relief by periradicular infiltration in patients with intraforaminal nerve root irritation.