Nerve injury following ultrasound-guided nerve root block with 2% lidocaine for shoulder manipulation: a case report

Shoulder manipulation under ultrasound (US)-guided C5 and C6 nerve root block is effective for treating refractory adhesive capsulitis (AC). We herein report the development of cervical nerve root injury following manipulation under anesthesia (MUA) in a patient with AC. A 47-year-old woman underwent shoulder manipulation under US-guided C5 and C6 root block with 2% lidocaine for the management of AC-induced shoulder pain. For the procedure, 3 mL of 2% lidocaine (total of 6 mL) was injected around each C5 and C6 nerve root under US guidance. Seven days after the procedure, the patient visited a university hospital because of severe neuropathic pain (numeric rating scale score of 9) in the right anterior arm, lateral arm, and forearm areas. Sensory deficits in the corresponding C5 and C6 dermatomes and motor weakness of the right shoulder abductor, elbow flexor, and wrist extensor were observed. Electrophysiologic studies demonstrated C5 and C6 nerve root injury. The patient was diagnosed with right C5 and C6 nerve root injury following MUA, and lidocaine toxicity or ischemia was the suspected cause. Clinicians should be mindful of the possibility of this complication.

The Association Between the Rotator Cuff Status and the Severity and Recovery of Weakness in the Shoulder Abductor Strength in a Case of Proximal Type Cervical Spondylotic Amyotrophy

Study Design: Case series study. Objective: We aimed to clarify the prevalence of rotator cuff tear (RCT), and the association between RCT and the severity and prognosis in patients with proximal type cervical spondylotic amyotrophy (CSA). Methods: We retrospectively analyzed 35 proximal type CSA patients who were treated conservatively. The following data was collected: age, rotator cuff status on MRI, manual muscle test (MMT) score of shoulder abductor and biceps brachii muscles both at the first visit and final follow-up. We investigated the prevalence of RCT and the association between the rotator cuff status, and the severity and recovery of upper extremity weakness in patients with proximal type CSA. Results: Of the 35 patients, 21 had an RCT on MRI, indicating that the prevalence of RCT in patients with proximal type CSA was 60%. An age-adjusted analysis showed that the presence of RCT was significantly associated with the MMT score of the shoulder abductor muscles both at the first visit and at the final follow-up. The presence of RCT was significantly associated with the recovery of the shoulder abductor muscles. The size of the RCT was negatively correlated with the MMT score of the shoulder abductor muscles at the final follow-up. The size of the RCT was independently correlated with the change of the MMT score of the shoulder abductor muscles. Conclusion: RCT was detected in >50% in patients with proximal type CSA, and the presence and severity of RCT can be used as prognostic factors for proximal type CSA patients who are treated conservatively.

Assessing the usage of indirect motor pathways following a hemiparetic stroke

A hallmark impairment in a hemiparetic stroke is a loss of independent joint control resulting in abnormal co-activation of shoulder abductor and elbow flexor muscles in their paretic arm, clinically known as the flexion synergy. The flexion synergy appears while generating shoulder abduction (SABD) torques as lifting the paretic arm. This likely be caused by an increased reliance on contralesional indirect motor pathways following damage to direct corticospinal projections. The assessment of functional connectivity between brain and muscle signals, i.e., brain-muscle connectivity (BMC), may provide insight into such changes to the usage of motor pathways. Our previous model simulation shows that multi-synaptic connections along the indirect motor pathway can generate nonlinear connectivity. We hypothesize that increased usage of indirect motor pathways (as increasing SABD load) will lead to an increase of nonlinear BMC. To test this hypothesis, we measured brain activity, muscle activity from shoulder abductors when stroke participants generate 20% and 40% of maximum SABD torque with their paretic arm. We computed both linear and nonlinear BMC between EEG and EMG. We found dominant nonlinear BMC at contralesional/ipsilateral hemisphere for stroke, whose magnitude increased with the SABD load. These results supported our hypothesis and indicated that nonlinear BMC could provide a quantitative indicator for determining the usage of indirect motor pathways following a hemiparetic stroke.