Fine-needle percutaneous muscle microbiopsy technique as a feasible tool to address histological analysis in young children with cerebral palsy and age-matched typically developing children

A pilot feasibility study of a minimally invasive technique to collect microbiopsies from sternocleidomastoid muscle for histological analysis in humans

BACKGROUND

The fine-needle (microbiopsy) technique may be suitable for sampling extradiaphragmatic respiratory muscles, but has so far never been used for this purpose. If feasible it would allow to study structural properties and adaptations of these muscles in response to disuse or loading interventions in humans. The sternocleidomastoid muscle (SCM) might be a promising target.

AIM

To assess the feasibility of the microbiopsy technique to obtain muscle tissue of good-quality with cross-sectionally oriented muscle fibres for immunohistochemical analyses of fibre type composition, number of capillaries and satellite cells in human SCM.

METHODS

Three to five SCM microbiopsies were taken bilaterally under ultrasound guidance in four fresh-frozen human cadavers, and six recently deceased adult patients in the intensive care unit (ICU). Biopsies were frozen in liquid nitrogen-cooled isopentane. Sections were stained for presence and quality of muscle tissue (Hematoxylin&Eosin), fibre typing (myosin heavy chain immunostaining), capillaries (CD31 immunostaining), and satellite cells amount (Pax7 immunostaining).

RESULTS

Biopsy collection was poor in fresh-frozen cadavers, while muscle biopsies were successfully collected in 87 % of all samples from recently deceased ICU patients. Good-quality muscle biopsies, with cross-sectionally oriented fibres (average:131 ± 79, range:30-343 fibres), were obtained from at least one sample per deceased subject. Staining procedures were successful, allowing analyses of fibre type composition, number of capillaries and satellite cells.

CONCLUSION

In six recently deceased ICU patients, it was feasible to collect good-quality muscle tissue with cross-sectionally oriented fibres from the human SCM for immunohistochemical analyses of fibre type composition, number of capillaries and satellite cells.

Short-Term Effects of Botulinum Toxin-A Injection on the Medial Gastrocnemius Histological Features in Ambulant Children with Cerebral Palsy: A Longitudinal Pilot Study

Botulinum toxin-A (BoNT-A) injection is known to exert beneficial effects on muscle tone, joint mobility and gait in children with cerebral palsy (CP). However, recent animal and human studies have raised the concern that BoNT-A might be harmful to muscle integrity. In CP-children, the impact of BoNT-A on muscle structure has been poorly studied, and inconsistent results have been reported. This study was aimed at determining the time course effect of a single BoNT-A administration on medial gastrocnemius (MG) morphology in CP-children. MG microbiopsies from 12 ambulant and BoNT-A-naïve CP-children (age, 3.4 (2.3) years, ranging from 2.5 to 7.8 years; seven boys and five girls; GMFCS I = 5, II = 4 and III = 3) were collected before and 3 and 6 months after BoNT-A treatment to analyze the fiber cross-sectional area (fCSA) and proportion; capillarization; and satellite cell (SC) content. Compared with the baseline, the fCSA decreased at 3 months (-14%, NS) and increased at 6 months (+13%, NS). Fiber size variability was significantly higher at 3 months (type I: +56%, p = 0.032; type IIa: +37%, p = 0.032) and 6 months (type I: +69%, p = 0.04; type IIa: +121%, p = 0.032) compared with the baseline. The higher type I proportion seen at 3 months was still present and more pronounced at 6 months (type I: +17%, p = 0.04; type IIx: -65%, p = 0.032). The capillary fiber density was reduced at 3 months (type I: -43%, NS; type II: -44%, p = 0.0320) but normalized at 6 months. There was a non-significant increase in SC/100 fibers at 3 months (+75%, NS) and 6 months (+40%, NS) compared with the baseline. These preliminary data suggest that BoNT-A induced alterations in the MG of children with CP, which were still present 6 months after BoNT-A injection but with signs of muscle recovery.