A protocol-based treatment plan to improve shoulder function in children with brachial plexus birth injury: a comparative study

Children with permanent brachial plexus birth injury have a high risk of developing posterior shoulder subluxation. In 2010, we implemented a protocol to reduce the incidence of this deformity, including early passive exercises, ultrasound screening, botulinum toxin-A injections, shoulder splinting and targeted surgeries. Two-hundred and thirty-seven consecutive children treated at our institution, with a mean follow-up of 11 years (range 1 to 17) were compared in three groups: children born from 1995 to 1999 ( n = 53), 2000–2009 ( n = 109) and 2010–2019 ( n = 75). Posterior shoulder subluxation developed in 48% of all patients but the mean age at detection of shoulder subluxation decreased from 5 years to 4.9 months. Need for shoulder relocation surgery also decreased from 28% to 7%. Mean active shoulder external rotation in adduction improved from 2° to 46°. In conclusion, our established protocol has the potential to reduce the incidence of posterior shoulder subluxation in children with brachial plexus birth injury. Level of evidence: II

Mechanisms governing protective pregnancy-induced adaptions of the pelvic floor muscles in the rat pre-clinical model

Background: The intrinsic properties of pelvic soft tissues in women who do and do not sustain birth injuries are likely divergent, however little is known about this. Rat pelvic floor muscles undergo protective pregnancy-induced structural adaptations, sarcomerogenesis and increase in intramuscular collagen content, that protect against birth injury. Objectives: We aimed to test the following hypotheses: 1) increased mechanical load of gravid uterus drives antepartum adaptations; 2) load-induced changes are sufficient to protect pelvic muscles from birth injury. Study Design: Independent effects of load uncoupled from hormonal milieu of pregnancy were tested in 3- to 4-month-old Sprague-Dawley rats randomly divided into four groups, N=5-10/group: (1) load-/pregnancy hormones- (controls); (2) load+/pregnancy hormones-; (3) reduced load/pregnancy hormones+; (4) load+/pregnancy hormones+. Mechanical load simulating a gravid uterus was simulated by weighing uterine horns with beads similar to fetal rat size and weight. Reduced load was achieved by unilateral pregnancy after unilateral uterine horn ligation. To assess acute and chronic phases required for sarcomerogenesis, rats were sacrificed at 4 hours or 21 days post bead loading. Coccygeus, iliocaudalis, pubocaudalis and non-pelvic tibialis anterior were harvested for myofiber and sarcomere length measurements. Intramuscular collagen content was assessed using hydroxyproline assay. Additional 20 load+/pregnancy hormones- rats underwent vaginal distention to determine whether load-induced changes are sufficient to protect from mechanical muscle injury in response to parturition-associated strains of various magnitude. Data, compared using two-way repeated measures analysis of variance/pairwise comparisons, are presented as mean +/- standard error of mean. Results: Acute increase in load resulted in significant pelvic floor muscle stretch, accompanied by acute increase in sarcomere length compared to non-loaded control muscles (coccygeus: 2.69+/-0.03 vs 2.30+/-0.06 micrometers, P<0.001; pubocaudalis: 2.71+/-0.04 vs 2.25+/-0.03 micrometers, P<0.0001; iliocaudalis: 2.80+/-0.06 vs 2.35+/-0.04 micrometers, P<0.0001). After 21 days of sustained load, sarcomeres returned to operational length in all pelvic muscles (P>0.05). However, the myofibers remained significantly longer in load+/pregnancy hormones- compared to load-/pregnancy hormones- in coccygeus (13.33+/-0.94 vs 9.97+/-0.26 millimeters, P<0.0001) and pubocaudalis (21.20+/-0.52 vs 19.52+/-0.34 millimeters, P<0.04) and not different from load+/pregnancy hormones+ (12.82+/-0.30 and 22.53+/-0.32millimeters, respectively, P>0.1), indicating that sustained load induced sarcomerogenesis in these muscles. Intramuscular collagen content in load+/pregnancy hormones- group was significantly greater relative to controls in coccygeus (6.55+/-0.85 vs 3.11+/-0.47 micrograms/milligram, P<0.001) and pubocaudalis (5.93+/-0.79 vs 3.46+/-0.52 micrograms/milligram, P<0.05) and not different from load+/pregnancy hormones+ (7.45+/-0.65 and 6.05+/-0.62 micrograms/milligram, respectively, P>0.5). Iliocaudalis required both mechanical and endocrine cues for sarcomerogenesis. Tibialis anterior was not affected by mechanical or endocrine alterations. Despite equivalent extent of adaptations, load-induced changes were only partially protective against sarcomere hyperelongation. Conclusions: Load induces plasticity of the intrinsic pelvic floor muscle components that renders protection against mechanical birth injury. The protective effect, which varies between individual muscles and strain magnitudes, is further augmented by the presence of pregnancy hormones. Maximizing impact of mechanical load on pelvic floor muscles during pregnancy, such as with specialized pelvic floor muscle stretching regimens, is a potentially actionable target for augmenting pregnancy-induced adaptations to decrease birth injury in women who may otherwise have incomplete antepartum muscle adaptations.

The role of muscle stem cells and fibro-adipogenic progenitors in female pelvic floor muscle regeneration following birth injury

Pelvic floor muscle (PFM) injury during childbirth is a key risk factor for subsequent pelvic floor disorders that affect millions of women worldwide. Muscle stem cells (MuSCs) play a central role in the regeneration of injured skeletal muscles, where they activate, proliferate, and differentiate to assure myogenesis needed for muscle recovery. For robust regenerative function, MuSCs require the support of fibro-adipogenic progenitors (FAPs) and immune cells. To elucidate the role of MuSCs, FAPs, and immune infiltrate in female PFM regeneration, we used radiation to perturb the system and followed PFM recovery in a simulated birth injury (SBI) rat model. Non-irradiated and irradiated rats were euthanized at 3,7, 10, and 28 days after SBI; PFMs were harvested and prepared for immunohistochemistry. Cross sectional area (CSA) of all PFM myofibers 28 days after injury in irradiated animals was significantly lower relative to non-irradiated injured controls, indicating impairment of PFM recovery. Following SBI in non-irradiated animals, the number of MuSCs and FAPs expanded significantly at 7 and 3 days after injury, respectively; this expansion did not occur in irradiated animals at the same time points. CSA of embryonic myosin heavy chain (eMyHC, marker of newly regenerated myofibers) positive fibers was also significantly smaller following SBI in irradiated muscles compared to PFMs from non-irradiated injured controls at 7 days. Our results demonstrate that loss of function and decreased expansion of MuSCs and FAPs associated with irradiation results in impaired PFM recovery, signifying essential roles for MuSCs and FAPs in the regenerative process of female PFMs after birth injury. These findings can inform the identification of novel preventative and therapeutic targets and the development of new treatments for PFM dysfunction and associated pelvic floor disorders.

Factors associated with birth injuries in neonates admitted to the neonatal intensive care unit: a retrospective study in a Ghanaian tertiary care setting

Background: A birth injury is structural damage or functional deterioration of the neonate’s body due to a traumatic incident at birth. The prevalence and the type of birth injury vary from place to place. There is paucity of data on the prevalence of birth injuries in Ghana. Objective: The study aimed to determine the prevalence and factors associated with birth injury in neonates admitted in a tertiary institution in Northern Ghana. Methods: This was a quantitative retrospective study carried out on neonates admitted to the neonatal intensive care unit (NICU) of the Tamale Teaching Hospital between January 2018 through December 2019. Results: Out of 5590 neonates admitted to the NICU, 205 were noted to have various forms of birth injury corresponding to a prevalence of 3.66%(37 per 1000 neonates admitted to our unit). Majority were male (n=123/205, 60.0%), most deliveries occurred in the study hospital(n=143/205, 69.75%), and spontaneous vaginal delivery accounted for 70.73% (n=145/205). Extracranial injuries (n=146/221, 66.06%) were the most common form of birth injury. Next was musculoskeletal injuries (n=41/221, 18.55%) with humeral fractures (n=15/221, 6.78%) being the most frequent in this category. Among the neonates with birth injuries there were 23 deaths recorded (11.22%) all but one of whom had associated birth asphyxia. Birth injuries were significantly associated with place of delivery(p=0.029). Out-born babies were more likely to have extracranial injuries (adjusted odds ratio,5.10; 95% CI: 1.53-16.94;p=0.008). Conclusion: Extracranial injuries were the most common in this study. Place of delivery was significantly associated with birth injuries. Building the capacity of health care professionals is essential to reduce incidence of birth injuries. Some of these injuries can be avoided if high risk pregnancies are referred early to institutions that have the resources and skill to deliver such babies.