Characteristics of Upper Extremity Recovery in Acute Flaccid Myelitis: A Case Series

Selective nerve transfers to restore shoulder abduction and flexion in acute flaccid myelitis: A case report

Acute flaccid myelitis (AFM) is a polio-like condition predominantly affecting children that is characterized by acute-onset, asymmetric flaccid paralysis, often preceded by a prodromal fever or viral illness. With prompt diagnosis and early surgical referral, nerve transfers may be performed to improve function. Highly selective nerve transfers are ideal to preserve existing functions while targeting specific deficits. In this report, we present a case of a double fascicular nerve transfer of median and ulnar nerve fascicles to the axillary nerve, combined with selective transfer of the spinal accessory nerve to the supraspinatus branch of the suprascapular nerve, performed for a 5-year-old girl who developed AFM after an upper respiratory infection. Six months after the onset of the patient's symptoms, the patient had continued weakness of shoulder flexion and abduction, atrophy of the deltoid, and supraspinatus muscles, though needle electromyography revealed a functioning infraspinatus muscle. The patient had no post-operative complications and at 2 years of postoperative follow up achieved shoulder abduction and flexion Active Movement Scale scores of 7/7 compared to preoperative scores of 2/7, with no loss of function in the donor nerve domains. The patient showed active shoulder abduction against gravity to 90° from 30° preoperatively and shoulder flexion to 180° from 15° preoperatively. This case report shows that highly selective nerve transfers may preserve existing functions while targeting specific deficits. A double fascicular transfer from the median and ulnar nerves to axillary nerve may provide abundant axons for functional recovery.

Nerve Transfer Surgery in Acute Flaccid Myelitis: Prognostic Factors, Long-Term Outcomes, Comparison With Natural History

BACKGROUND

Nerve transfer surgery is sometimes offered to patients with acute flaccid myelitis (AFM). The objectives of this study were to evaluate surgical efficacy, assess which clinical and neurophysiological data are valuable for preoperative planning, and report long-term outcomes.

METHODS

This is a single-center, retrospective case series of patients with AFM who received nerve transfer surgery. All patients had preoperative electromyography and nerve conduction studies (EMG/NCS). Matched control muscles that did not receive nerve transfer surgery were defined in the same cohort.

RESULTS

Ten patients meeting inclusion criteria received a total of 23 nerve transfers (19 upper extremity, four lower extremity). The mean age at symptom onset was 3.8 years, surgery was 0.5 to 1.25 years after diagnosis, and mean follow-up was 2.3 years (range 1.3 to 4.5 years). Among muscles with preoperative strength Medical Research Council (MRC) grade 0, muscles receiving nerve transfers performed significantly better than those that did not (MRC grade 2.17 ± 0.42 vs 0 ± 0, respectively, P = 0.0001). Preoperative EMG/NCS predicted worse outcomes in recipient muscles with more abundant acute denervation potentials (P = 0.0098). Donor nerves found to be partially denervated performed equally well as unaffected nerves. Limited data suggested functional improvement accompanying strength recovery.

CONCLUSIONS

Nerve transfer surgery is an effective strategy to restore strength for patients with AFM with persistent, severe motor deficits. Postoperative outcomes in patients with complete paralysis are better than the natural history of disease. This study demonstrates the utility of preoperative clinical and electrophysiological data in guiding patient selection for nerve transfer surgery.

Diagnostic Accuracy of Manual Muscle Testing to Identify Nerve Transfer Candidates in Children with Acute Flaccid Myelitis

BACKGROUND

Manual muscle testing is a mainstay of strength assessment despite not having been compared with intraoperative electrical stimulation of peripheral nerves.

METHODS

Intraoperative electrical stimulation served as the reference standard in evaluating predictive accuracy of the Active Movement Scale (AMS) and the Medical Research Council (MRC) scale. Retrospective consecutive sampling of all patients with AFM who underwent exploration or nerve transfer at a pediatric multidisciplinary brachial plexus and peripheral nerve center from March of 2016 to July of 2020 were included. The nonparametric area under the curve (AUC) was calculated. Optimal cutoff score (Youden J ) and diagnostic accuracy values were reported. The AMS and MRC scale were directly compared for predictive superiority.

RESULTS

A total of 181 upper extremity nerves (73 donor nerve candidates and 108 recipient nerve candidates) were tested intraoperatively from 40 children (mean age ± SD, 7.9 ± 4.9 years). The scales performed similarly ( P = 0.953) in classifying suitable donor nerves with satisfactory accuracy (AUC AMS , 71.5%; AUC MRC , 70.7%; optimal cutoff, AMS >5 and MRC >2). The scales performed similarly ( P = 0.688) in classifying suitable recipient nerves with good accuracy (AUC AMS , 92.1%; AUC MRC :, 94.9%; optimal cutoff, AMS ≤3 and MRC ≤1).

CONCLUSIONS

Manual muscle testing is an accurate, noninvasive means of identifying donor and recipient nerves for transfer in children with acute flaccid myelitis. The utility of these results is in minimizing unexpected findings in the operating room and aiding in the development of contingency plans. Further research may extend these findings to test the validity of manual muscle testing as an outcome measure of the success of nerve transfer.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Diagnostic, I.

Acute Flaccid Myelitis: Review of Clinical Features, Diagnosis, and Management with Nerve Transfers

BACKGROUND

Acute flaccid myelitis (AFM) is a devastating neurologic condition in children, manifesting as acute limb weakness and/or paralysis. Despite increased awareness of AFM following initiation of U.S. surveillance in 2014, no treatment consensus exists. The purpose of this systematic review was to summarize the most current knowledge regarding AFM epidemiology, cause, clinical features, diagnosis, and supportive and operative management, including nerve transfer.

METHODS

The authors systematically reviewed the literature based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using multiple databases to search the keywords ("acute flaccid myelitis"), ('acute flaccid myelitis'/exp OR 'acute flaccid myelitis'), and (Acute AND flaccid AND myelitis). Included articles reported on (1) AFM diagnosis and (2) patient-specific data regarding epidemiology, cause, clinical features, diagnostic features, or management of AFM.

RESULTS

Ninety-nine articles were included in this review. The precise cause and pathophysiologic mechanism of AFM remain undetermined, but AFM is strongly associated with nonpolio enterovirus infections. Clinical presentation typically comprises preceding viral prodrome, pleocytosis, spinal cord lesions on T2-weighted magnetic resonance imaging, and acute onset of flaccid weakness/paralysis with hyporeflexia in at least one extremity. Supportive care includes medical therapy and rehabilitation. Early studies of nerve transfer for AFM have shown favorable outcomes for patients with persistent weakness.

CONCLUSIONS

Supportive care and physical therapy are the foundation of a multidisciplinary approach to managing AFM. For patients with persistent limb weakness, nerve transfer has shown promise for improving function in distal muscle groups. Surgeons must consider potential spontaneous recovery, patient selection, donor nerve availability, recipient nerve appropriateness, and procedure timing.

Upper extremity nerve transfers for acute flaccid myelitis: a systematic literature review

BACKGROUND

Acute flaccid myelitis (AFM) is a rare disease that commonly affects young children. AFM's pathophysiology involves loss of lower motor neurons following a viral infection and induces acute asymmetric flaccid paralysis most commonly in the upper extremities. Nerve transfers have emerged as a treatment option for these patients with permanent motor deficits.

OBJECTIVE

To summarize the literature and report safety and efficacy outcomes following nerve transfers for recovery of shoulder abduction and external rotation, and elbow flexion and extension in pediatric patients with AFM. Recovery of at least antigravity function was defined as a successful outcome. This systematic review was performed according to the PRISMA guidelines. The PubMed, Embase and Cochrane databases were utilized.

RESULTS

Five studies comprising 44 patients (median age 2.95 years; 71% male), and 93 upper extremity nerve transfers were included. Thirty-eight patients received 65 nerve transfer procedures aiming for recovery of shoulder abduction and/or external rotation with a transfer to the axillary and/or suprascapular nerve. The recovery of shoulder abduction and external rotation was achieved in 40.7% (n = 11/27) and 60% (n = 6/10) of patients, respectively. Time from injury to surgery showed an inverse relationship with the odds for successful recovery (OR: 0.81; 95% CI: 0.64-1.02; p = 0.07); however, statistical significance was not reached. Successful recovery of elbow flexion with a transfer to the musculocutaneous was reported at a rate of 92.3% (n = 12/13). Successful re-innervation of the radial nerve with recovery of elbow extension was found in 75% (n = 6/8) of patients. No complications were reported.

CONCLUSIONS

Upper extremity nerve transfers appear to be promising and safe for AFM patients. Shoulder abduction is the most challenging upper extremity function to recover. Further studies are warranted to identify whether nerve transfers are associated with superior outcomes when performed earlier.

Surgical Innovations to Restore Function in Pediatric Peripheral Nerve Conditions

Peripheral nerve injuries in children can result in devastating lifelong deficits. Because of the time-sensitive nature of muscle viability and the limited speed of nerve regeneration, early recognition and treatment of nerve injuries are essential to restore function. Innovative surgical techniques have been developed to combat the regenerative length and speed; these include nerve transfers. Nerve transfers involve transferring a healthy, expendable donor nerve to an injured nerve to restore movement and sensation. Nerve transfers are frequently used to treat children affected by conditions, including UE trauma, brachial plexus birth injury, and acute flaccid myelitis. Pediatricians play an important role in the outcomes of children with these conditions through early diagnosis and timely referrals. With this review, we aim to provide awareness of state-of-the-art surgical treatment options that significantly improve the function of children with traumatic nerve injuries, brachial plexus birth injury, and acute flaccid myelitis.

Recommendations for Therapy following Nerve Transfer for Children with Acute Flaccid Myelitis

AIM

To provide recommendations for pre- and post-operative occupational and physical therapy for children with acute flaccid myelitis (AFM).

METHODS

Writing panel members consisted of an interdisciplinary team of seven healthcare professionals specializing in the care of children with AFM. The panel reviewed background material on AFM, nerve transfer, and rehabilitation principles applied to pediatrics. Recommendations were prioritized if evidence was available. Where there was no known evidence to support a recommendation, this was noted.

RECOMMENDATIONS

Communication and coordination among interprofessional team members are vital to a comprehensive family-centered rehabilitation program. Surgical planning should include team preparation accounting for frequency, duration, and timing of treatment, as well as individual characteristics and developmental status of the child. Recommendations for pre-operative and six phases of post-operative therapy address assessment, strengthening, range of motion, orthoses, performance of functional activity, and support of the family.

CONCLUSION

Rehabilitation following nerve transfer in children with AFM requires interdisciplinary collaboration and a multisystem approach to assessment and treatment. As new evidence becomes available, recommendations may be revised or replaced accordingly.