Acute Flaccid Myelitis: Mid-Term Clinical Course of Knee Extension Paralysis and Outcomes of Nerve Transfer.

BACKGROUND: Acute flaccid myelitis (AFM) is a rare debilitating poliomyelitis-like illness characterized by the sudden onset of flaccid palsy in the extremities. The purpose of this study was to report the mid-term clinical course of knee extension in AFM and the effect of contralateral obturator nerve-to-femoral nerve transfer (CONFNT) for restoration of knee extension in AFM. METHODS: Twenty-six patients with lower extremity palsy due to AFM were referred to our clinic for possible surgical reconstruction. Their median age was 4.0 years, and the first evaluation of the palsy was done at a mean of 6 months after paralysis onset. The paralysis ranged from lower limb monoplegia to quadriplegia. The clinical course of knee extension was assessed using the British Medical Research Council (MRC) grading scale and surface electromyography (EMG). Five patients with unilateral paralysis of knee extension underwent CONFNT. RESULTS: The mean follow-up period for 19 limbs with complete paralysis of knee extension (MRC grade M0) in 13 patients who were evaluated for spontaneous recovery was 43 months. No patient who had complete paralysis of knee extension at >6 months and paralysis of the hip adductor muscle had improvement of knee extension to better than M2. Five of the original 26 patients were treated with CONFNT and followed for a mean of 61 months. Two of 5 patients had the CONFNT ≤8 months after paralysis onset and obtained M4 knee extension. Only 1 of the 3 patients with CONFNT performed approximately 12 months after paralysis onset obtained M3 knee extension; the other 2 obtained only M1 or M2 knee extension. CONCLUSIONS: The paralysis of the lower extremity in our patients with AFM was similar to that in poliomyelitis. However, in AFM, spontaneous recovery of knee extension was possible if there were signs of recovery from hip adductor paralysis up to 6 months after paralysis onset. CONFNT may enhance the recovery of knee extension and seems to be a reliable reconstruction for restoring knee extension if performed no more than 8 months after paralysis onset. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Contralateral Obturator Nerve to Femoral Nerve Transfer for Restoration of Knee Extension After Acute Flaccid Myelitis: A Case Report.

CASE: A 7-year-old boy presented with left femoral and obturator nerves (ONs) palsy after an asthmatic attack with a viral prodrome, and his right lower limb was unaffected. He was diagnosed with acute flaccid myelitis (AFM) after positive spinal magnetic resonance imaging findings. After contralateral ON to femoral nerve transfer (CONFNT), his left quadriceps was reinnervated at 5.5 months, full knee extension was recovered at 14 months, and good functional outcomes were achieved at 31 months. CONCLUSIONS: This first clinical report on CONFNT demonstrated a feasible good alternative in treating young patients with AFM with unilateral L2-L4 palsy and short duration of deficit.

Age-related changes in two- and three-dimensional morphology of type-identified endplates in the rat diaphragm.

To examine the age-related morphological changes in the motor endplate of type-identified muscle fibers, 20 male Wister rats were divided into 2-month-, 10-month-, 24-month- and 30-month-old groups (n = 5 in each group). Three segments of mid-costal diaphragm muscle were removed, and then a fluorescent double-labeling technique was used to visualize the endplates on type-identified muscle fibers. Endplates were labeled with alpha-bungarotoxin-tetramethylrhodamine. Muscle segments were first incubated in antibodies to MHC isoforms (I and/or IIa) and then labeled by a second antibody with FITC. The endplates were imaged using 3D confocal microscopy with two lasers. In each age group, the planar area and volume of endplates on type-IIx/b muscle fibers were larger than those on type-I and -IIa muscle fibers, while the normalized planar areas of the endplate (endplate area/muscle fiber diameter) and the mean thickness of the endplate (volume/endplate area) were identical on all fiber types within the same age group. Decreased endplate density (endplate area/surrounding area) in the old diaphragm indicated fragmentation of the endplate, especially on type IIx/b fibers. These morphological changes may lead to functional deficiency and selective denervation of type-IIx/b muscle fiber with aging.