Comparing Electrical Stimulation With and Without Ultrasound Guidance for Phenol Neurolysis to the Musculocutaneous Nerve.

BACKGROUND: Ultrasound guidance is increasingly being used for neurolytic procedures that have traditionally been done with electrical stimulation (e-stim) guidance alone. Ultrasound visualization with e-stim-guided neurolysis can potentially allow adjustments in injection protocols that will reduce the volume of neurolytic agent needed to achieve clinical improvement. OBJECTIVE: This study compared e-stim only to e-stim with ultrasound guidance in phenol neurolysis of the musculocutaneous nerve (MCN) for elbow flexor spasticity. We also evaluated the ultrasound appearance of the MCN in this population. DESIGN: Retrospective review. SETTING: University hospital outpatient clinic. PARTICIPANTS: Adults (N = 167) receiving phenol neurolysis to the MCN for treatment of elbow flexor spasticity between 1997 and 2014 and adult control subjects. METHODS: For each phenol injection of the MCN, the method of guidance, volume of phenol injected, technical success, improved range of motion at the elbow postinjection, adverse effects, reason for termination of injections, and details of concomitant botulinum toxin injection were recorded. The ultrasound appearance of the MCN, including nerve cross-sectional area and shape, were recorded and compared between groups. MAIN OUTCOME MEASURES: The volume of phenol injected and MCN cross-sectional area and shape as demonstrated by ultrasound. RESULTS: The addition of ultrasound to e-stim-guided phenol neurolysis was associated with lower doses of phenol when compared to e-stim guidance alone (2.31 mL versus 3.69 mL, P < .001). With subsequent injections, the dose of phenol increased with e-stim guidance (P < .001), but not with e-stim and ultrasound guidance (P = .95). Both methods of guidance had high technical success, improved ROM at elbow postinjection, and low rates of adverse events. In comparing the ultrasound appearance of the MCN in patients with spasticity to that of normal controls, there was no difference in the cross-sectional area of the nerve, but there was more variability in shape. CONCLUSIONS: Combined e-stim and ultrasound guidance during phenol neurolysis to the MCN allows a smaller volume of phenol to be used for equal effect, both at initial and repeat injection. The MCN shape was more variable in individuals with spasticity; this should be recognized so as to successfully locate the nerve to perform neurolysis. LEVEL OF EVIDENCE: IV.

Effects of Anesthetic Fluid Injectates on Lesion Sizes in Cooled Radiofrequency Ablation.

STUDY DESIGN: Nonrandomized trial. OBJECTIVE: This is an ex vivo study using pork chops to simulate human vertebra to determine the effects of various anesthetic fluids injectates and concentrations on lesion size and shape created when using cooled radiofrequency ablation. Secondary objective is to determine the effects of various time durations of applied lesion on lesion size created. Our final objective is to determine the effects of fluid injectates on tissue temperature and impedance. SUMMARY OF BACKGROUND DATA: Radiofrequency neurotomy is a therapeutic procedure involving ablation of sensory afferent nerves to the vertebral zygapophyseal joints. Larger lesions increase the likelihood the target nerve is ablated. METHODS: Before cooled radiofrequency ablation, tissue was injected with either 0.9% normal saline, 1% lidocaine, 2% lidocaine, 0.25% bupivacaine, 0.5% bupivacaine, 0.75% bupivacaine, 0.2% ropivacaine, 0.5% ropivacaine, or 1% ropivacaine. Duration of cooled radiofrequency was either 45, 90, or 150 seconds. RESULTS: There was no significant difference in the size of the lesion created when using different injectates and concentrations. There was no significant difference in the size of the lesion created when applying a 90 seconds duration lesion compared with a 150 seconds duration lesion. CONCLUSION: Applying a 90 seconds duration lesion can be considered in clinical use for cooled radiofrequency ablation. The use of an injectate did not significantly alter the size or desired spherical shape of the lesion created, did not significantly alter the time required to create the lesion, and did not significantly lower the temperature threshold. The study is limited by the use of ex vivo tissue which does not account for the effects of tissue perfusion. The use of an injectate before cooled radiofrequency ablation can be made at the interventionalist's discretion. LEVEL OF EVIDENCE: N/A.

Lateral Antebrachial Cutaneous Nerve Entrapment After Shoulder Arthroscopy: A Case Report.

The lateral antebrachial cutaneous nerve (LABCN) is a distal sensory branch of the musculocutaneous nerve that innervates the radial aspect of the forearm. Cases of LABCN injury from trauma and chronic compression have been reported. A case of musculocutaneous nerve injury after a biceps tenodesis has also been reported. This case report describes an LABCN injury and forearm pain after a biceps tenodesis procedure. Using a multifaceted diagnostic approach of electrodiagnostics and magnetic resonance neurography, the site of compression was appropriately localized. The patient ultimately achieved relief after a surgical decompression.