Electron microscopic findings in levator muscle biopsies of patients with isolated congenital or acquired ptosis

Levator palpebralis superioris histopathologic findings in congenital ptosis and surgical outcome after its resection: Is there any association?

PURPOSE

To evaluate the histopathologic findings of Levator palpebralis superioris (LPS) muscle biopsy after LPS resection for treatment of congenital ptosis and its possible relation with surgical outcomes.Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Author 4 Given name: [Seyed Mohsen] Last name [Rafizadeh]. Author 6 Given name: [Seyed Ali] Last name [Sonbolestan].Also, kindly confirm the details in the metadata are correct.The author names and the sequence are correct.

METHODS

Congenital ptosis patients were enrolled in this retrospective study. All of them underwent full ophthalmologic examination included of Margin-reflex distance 1 (MRD-1) and LPS function measurement preoperatively. The patients were followed for 3 months for the postoperative period and after that the measurements were repeated. Histologic parameters including percentages of fat, striated and smooth muscle, and fibrous tissue. The histopathologic findings and their possible correlation with the measurements are analyzed.

RESULTS

Sixty-seven patients with unilateral congenital ptosis were enrolled. 45 patients (67.2%) were males. The mean age of patients was 16.10 ± 11.18 years. The patients' MRD-1 was improved significantly from 0.82 ± 1.26 mm to 3.85 ± 1.25 mm after LPS resection (P = 0.000). The success rate was 80.3%. There were no correlations between MRD change and histopathologic tissue percentages but significant correlation was found between success of surgery and fibrous tissue percentage of resected sample (P = 0.033).

CONCLUSIONS

The histopathology of the LPS may be useful in prediction of surgical outcome after LPS resection in congenital ptosis patients. The percentage of fibrous tissue play an important role.

Advances in the genetics of congenital ptosis

Congenital ptosis, a birth defects presents at birth or by 1 year of age, is characterized by the drooping of the upper eyelid. either in isolation (non-syndromic) or with many different systemic disorders (syndromic). The estimated prevalence of ptosis (congenital & acquired) ranges from 0.79 to 1.99 per 10,000 people in different populations, and it is more prevalent in males. The underlying pathogenesis of congenital ptosis are myogenic and neurogenic, related to the development of muscles and nerves. Although most cases are sporadic, there are familial transmission characteristics, including autosomal dominant, recessive mode and X-linkage inheritance patterns. Moreover, some forms are due to chromosomal aberrations and mutations and deletions in mitochondrial DNA. Genes involved in simple congenital ptosis are ZFHX4 and COL25A1. The clinical aspects of various syndromes involving congenital ptosis are partly caused by single gene mutations. However, the pathogenesis of congenital ptosis is not fully understood. We review the reported epidemiology, genetics and clinical features of congenital ptosis and associated syndromes here.

Reduced mitochondrial fission and impaired energy metabolism in human primary skeletal muscle cells of Megaconial Congenital Muscular Dystrophy

Megaconial Congenital Muscular Dystrophy (CMD) is a rare autosomal recessive disorder characterized by enlarged mitochondria located mainly at the periphery of muscle fibers and caused by mutations in the Choline Kinase Beta (CHKB) gene. Although the pathogenesis of this disease is not well understood, there is accumulating evidence for the presence of mitochondrial dysfunction. In this study, we aimed to investigate whether imbalanced mitochondrial dynamics affects mitochondrial function and bioenergetic efficiency in skeletal muscle cells of Megaconial CMD. Immunofluorescence, confocal and transmission electron microscopy studies revealed impaired mitochondrial network, morphology, and localization in primary skeletal muscle cells of Megaconial CMD. The organelle disruption was specific only to skeletal muscle cells grown in culture. The expression levels of mitochondrial fission proteins (DRP1, MFF, FIS1) were found to be decreased significantly in both primary skeletal muscle cells and tissue sections of Megaconial CMD by Western blotting and/or immunofluorescence analysis. The metabolomic and fluxomic analysis, which were performed in Megaconial CMD for the first time, revealed decreased levels of phosphonucleotides, Krebs cycle intermediates, ATP, and altered energy metabolism pathways. Our results indicate that reduced mitochondrial fission and altered mitochondrial energy metabolism contribute to mitochondrial dysmorphology and dysfunction in the pathogenesis of Megaconial CMD.

A Study of Histopathologic Evaluation and Clinical Correlation for Isolated Congenital Myogenic Ptosis and Aponeurotic Ptosis

PURPOSE

To evaluate light microscopy and transmission electron microscopy findings of levator muscle/aponeurosis materials and their correlation with clinical findings in isolated congenital myogenic and aponeurotic blepharoptosis.

METHODS

Demographic and clinical data were obtained from patients. Qualitative and quantitative evaluations for muscle fiber morphology were performed using light microscopy and transmission electron microscopy on tissue samples which were obtained from the most proximal part of the aponeurosis excised during levator muscle/aponeurosis resection surgery.

RESULTS

Seventeen (55%) of the cases were isolated congenital myogenic ptosis, and 14 (45%) were aponeurotic ptosis. Muscle bundle splitting, cytoplasmic loss, and centrally located nuclei were observed in both groups. Muscle tissue covered 25% of the sample in 67% of the cases, 50% in 11%, 75% in 11%, and 100% in 11% in the myogenic group. In the aponeurotic group, muscle tissue covered 25% of the sample in 44.5% of the cases, 50% in 11%, and 100% in 44.5% (χ, p = 0.52). Myofibrillar loss areas accompanied by Z-line disorganization which were occupied by degenerated organelles were present in both groups under transmission electron microscopy, and findings were not significantly different between groups (χ, p > 0.05). Mean mitochondrial diameter was significantly larger in aponeurotic ptosis (Mann-Whitney U, p = 0.047). No correlation was found between functional and microscopic parameters.

CONCLUSION

Decreased amount of striated muscle and the presence of fiber damage indicators were observed in both groups. Muscle fiber loss in myogenic ptosis may be a feature of muscle dysgenesis. Ultrastructural damage in aponeurotic ptosis may be explained with increased oxidative stress or long-term contractile stress. Further genetic and immunohistochemical studies will be helpful to further understand the pathogenesis of diseases.

A review of the histopathological findings in myasthenia gravis: Clues to the pathogenesis of treatment-resistance in extraocular muscles

In myasthenia gravis autoantibodies target components of the neuromuscular junction causing variable degrees of weakness. In most cases, autoantibodies trigger complement-mediated endplate damage and extraocular muscles may be most susceptible. A proportion of MG cases develop treatment-resistant ophthalmoplegia. We reviewed publications spanning 65 years reporting the histopathological findings in the muscles and extraocular muscles of myasthenic patients to determine whether pathological changes in extraocular muscles differ from non-ocular muscles. As extraocular muscles represent a unique muscle allotype we also compared their histopathology in myasthenia to those in strabismus. We found that in myasthenia gravis, the non-ocular muscles frequently demonstrate neurogenic changes regardless of myasthenic serotype. Mitochondrial stress/damage was also frequent in myasthenic muscles and possibly more evident in muscle-specific kinase antibody-positive MG. Although myasthenia-associated paralysed extraocular muscles demonstrated prominent fibro-fatty replacement and mitochondrial alterations, these features appeared commonly in paralysed extraocular muscles of any cause. We postulate that extraocular muscles may be more susceptible than limb muscles to poor contractility as a consequence of myasthenia, resulting in a cascade of atrophy signaling pathways and altered mitochondrial homeostasis which contribute to the tipping point in developing treatment-resistant myasthenic ophthalmoplegia. Early strategies to improve force generation in extraocular muscles are critical.

Clinical trial comparing autogenous fascia lata sling and Gore-Tex suspension in bilateral congenital ptosis

PURPOSE

To study the effect of autogenous fascia lata sling (AFLS) versus Gore-Tex suspension (GTS) regarding the functional and aesthetic outcomes in patients with bilateral congenital ptosis.

PATIENTS AND METHODS

A prospective comparative randomized single-center study enrolled 110 patients with bilateral congenital ptosis. One group (n=55) underwent AFLS and the second group (n=55) underwent GTS. Exclusion criteria were good levator function, absent Bell's phenomenon, and abnormal ocular motility. Follow-up period was 2 years. Functional outcome was measured from digital photos by analysis of upper eyelid margin position relative to the superior limbus and classified as very good (<3 mm), good (3-5 mm), poor (>5 mm), and recurrent. Aesthetic outcome was assessed in terms of lid contour, symmetry of eyelid height, and lid crease presence. Complications were also reported.

RESULTS

Failure rate (recurrence and complications) was less in AFLS (P=0.035). Symmetrical lid height and good contour were more frequently attained by AFLS (P=0.007 and 0.047, respectively). However, the frequency of very good, good, poor, recurrence, lagopthalmos, ectropion, infection, and formed lid crease individually showed no statistically significant difference (P=0.252, 0.482, 1, 0.489, 0.438, 1, 0.618, and 0.506, respectively).

CONCLUSION

AFLS is a better choice in surgery for patients with bilateral congenital ptosis because it has fewer complications and a lesser recurrence rate than GTS.

Levator Palpebrae Biopsy and Diagnosis of Progressive External Ophthalmoplegia

Background:

Progressive external ophthalmoplegia (PEO) is a mitochondrial myopathy of ocular muscles. Diagnostic investigation usually involves limb skeletal muscle biopsy and molecular genetic studies, although diagnostic yield tends to be low. The purpose of this study was to evaluate the diagnostic yield obtained by analysis of levator palpebrae (LP) muscle tissue.

Methods:

This is a clinicopathologic study of 8 patients with a diagnosis of PEO, who had LP muscle biopsies as part of oculoplastic procedures. Six of these patients also had limb muscle biopsies. Histopathology, electron microscopy and genetic studies were performed.

Results:

Diagnostic histopathologic findings were present in 4/6 quadriceps biopsies, and 7/8 LP biopsies. Genetic testing on DNA extracted from LP muscle revealed abnormalities in 4 patients.

Conclusion:

In patients whose LP muscle demonstrate both genetic defects and histopathological abnormalities, the diagnosis of PEO can be confirmed without limb muscle biopsy. Patients having LP resection during oculoplastics procedures for treatment of ptosis may therefore be able to avoid a separate procedure for limb muscle biopsy. Further study is required to determine the specificity of these findings.

Mitochondrial Changes in Aging Orbicularis Oculi Muscles: Histologic and Genetic Analyses in Elderly Asian Patients

PURPOSE

We aimed to determine whether there was underlying mitochondrial myopathy in some aging patients diagnosed with involutional ptosis. We compared orbicularis oculi muscle from patients with ptosis and patients with dermatochalasis without ptosis, using histochemical and mitochondrial DNA (mtDNA) analysis.

DESIGN

This was a case-control study.

METHODS

We studied 10 patients with ptosis who underwent correction surgery, and 10 patients without ptosis, who had dermatochalasis surgery, all in 1 institution. Orbicularis oculi muscle was examined with standard muscle histochemistry; modified Gomori trichrome, nicotinamide adenine dinucleotide (NADH), succinyl dehydrogenase (SDH), cytochrome c oxidase (COX), and Congo red. Genetic analysis was performed for deletions of mtDNA.

RESULTS

The mean age of the group with ptosis was 67.6 years and that of the dermatochalasis group was 65.2 years. Inflammation, fibrosis, or amyloid was not present in the orbicularis of either ptosis or dermatochalasis group. There was no significant difference in ragged red fibers, NADH, SDH, or COX staining patterns between ptosis and dermatochalasis groups. One of 10 specimens in the ptosis group and 1 of 10 in the dermatochalasis group showed deletion of mtDNA.

CONCLUSIONS

Our study of orbicularis oculi muscle found no difference between patients with and without involutional ptosis. We conclude that the presence of ragged red fibers, subsarcolemmal NADH and SDH accentuation, and COX-negative staining patterns in orbicularis muscle could represent age-related involutional changes. The significance of deletion of mtDNA needs further investigation.

An autopsy case of chronic progressive external ophthalmoplegia with renal insufficiency

An autopsy of a 44-year-old Japanese woman with mitochondrial cytopathy confirmed the presence of chronic progressive external ophthalmoplegia (CPEO). Immunohistochemistry using antimitochondrial antibody was performed to observe the ultrastructure of the skeletal muscle and renal tissues. The patient was born of consanguineous parents, developed normally, and was of average intelligence. At 22 years of age, the patient noticed hearing loss, and subsequently, over time, developed a progressive generalized muscle weakness, which included limitation of eye movement and ptosis. At age 41, a muscle biopsy was performed using the modified Gomori trichrome method and demonstrated the presence of ragged red fibers. After the evaluation of her results in conjunction with her clinical course, she was diagnosed with CPEO. Renal insufficiency was discovered at age 30, and the patient died at the age of 44 of respiratory failure caused by respiratory muscle weakness and pneumonia. The autopsy revealed fiber size variation within the skeletal muscle, and an antimitochondrial antibody analysis demonstrated the accumulation of mitochondria between the bundles of myofibrils, as well as in subsarcolemmal locations. Ultrastructurally, abnormal mitochondria with disoriented cristae and paracrystalline inclusions were seen. Although no remarkable histological changes were noted in the kidneys, tubular epithelial cells exhibited accumulated abnormal mitochondria, similar to those seen in the skeletal muscle. Because mitochondrial diseases can affect other energy-dependent organs in addition to the skeletal muscle, immunohistochemical examinations employing an antimitochondrial antibody are useful for obtaining further ultrastructural observations that can assist in making a distinct diagnosis of this systemic disorder.

The changes in the energy metabolism of human muscle induced by training

The biochemical effects of training programmes have been studied with a kinetic model of central metabolism, using enzyme activities and metabolite concentrations measured at rest and after 30 s maximum-intensity exercise, collected before and after long and short periods of training, which differed only by the duration of the rest intervals. After short periods of training the glycolytic flux at rest was three times higher than it had been before training, whereas during exercise the flux and energy consumption remained the same as before training. Long periods of training had less effect on the glycolytic flux at rest, but increased it in response to exercise, increasing the contribution of oxidative phosphorylation.