Orbicularis oculi: morphological changes mimicking mitochondrial cytopathy in a series of control normal muscles

Damage to the orbicularis oculi muscle may impair the development of dermatochalasis

The purpose of this article is to investigate the changes that occur in the orbicularis oculi muscle (OOM) in patients with dermatochalasis. The OOM specimens from 26 patients were collected during upper eyelid blepharoplasty. Each specimen was divided into three parts, which were then examined using different techniques: formalin embedding for light microscopy, free freezing for histochemical examination, and fixation in 3% glutaraldehyde for electron microscopy. The severity of dermatochalasis was classified according to the anatomical landmarks. 78 specimens from patients with dermatochalasis were evaluated. Under light microscopy, specimens showed an increase in muscle fiber size variation, rounding of muscle fibers, and lobulation of myocytes in a fibrotic background. Under electron microscopy, loss of myofilaments, vacuolar vesicles, and swollen mitochondria were observed, along with osmophilic aggregates resembling nemadine bodies and collagen fibrils. A statistically significant association between the progression of dermatochalasis and the presence of aggregates resembling nemaline bodies was found (p- value < 0.005). Significant changes occur in the OOM in patients with dermatochalasis and the presence of aggregates resembling nemaline bodies is correlated with the degree of eyelid drooping. Thus, OOM may contribute in dermatochalasis progression.

Orbicularis Oculi Muscle Immunohistochemical, Metabolic, and Morphometric Differences in Affected and Nonaffected Sides in Hemifacial Spasm vs Healthy Subjects

BACKGROUND

Subtle morphological alterations have been reported even in the nonaffected side of the orbicularis oculi muscle in patients with hemifacial spasm. However, no previous study assessed immunohistochemical, metabolic, and morphometric alterations in orbicularis oculi muscle fibers in affected and nonaffected sides in patients with this condition, compared with samples obtained from healthy subjects. The purpose of this study is to objectively assess and compare orbicularis oculi muscle (OOM) samples of hemifacial spasm affected and nonaffected sides and healthy subjects.

METHODS

Orbicularis oculi samples from 8 patients with hemifacial spasm who had not been previously treated and 6 healthy subjects were prepared using hematoxylin and eosin, nicotinamide adenine dinucleotide tetrazolium reductase, cytochrome oxidase, succinate dehydrogenase, Gomori staining, and monoclonal antibodies against myosin slow and myosin fast. A digital image analysis software was used for objective analysis.

RESULTS

OOM fiber area was significantly greater in both affected ( P = 0.0379) and nonaffected sides ( P = 0.0012) of HFS samples when compared with control subjects' fibers. A significantly greater number of oxidative fibers were observed in both affected and nonaffected sides of patients with HFS when compared with control subjects ( P < 0.001 for both). A significantly greater percentage of slow fibers was observed in the affected side of HFS patients ( P = 0.0012) compared with control subjects.

CONCLUSIONS

This study's findings suggest that repeated contractions might lead to OOM fiber hypertrophy, increased mitochondrial metabolism, and possible conversion of fast-twitch orbicularis oculi muscle fibers into slow-twitch fibers in patients with HFS. Alterations were observed in affected and nonaffected sides, confirming initial findings that the nonaffected side is not normal in this unique condition.

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.

Recent Advances in Ophthalmic Plastic Surgery: Part 1-Eyelid

PURPOSE

The objective of this study was to provide an update of the current literature in ophthalmic and facial plastic surgery, specifically related to disorders of the eyelid.

DESIGN

This was a review of published literature from January 2012 to June 2013 METHODS: The authors conducted a PubMed literature search of English-language articles published between January 2012 and June 2013 using the following search terms: eyelid, congenital, acquired, infection, inflammation, trauma, tumor, ptosis, entropion, ectropion, lagophthalmos, botulinum toxin, fillers, blepharoplasty, and miscellaneous topics related to the disorders of the eyelid. The authors included original articles, review articles, and case reports with relevant new information that is of potential clinical use to a comprehensive ophthalmologist as well as to the subspecialist.

RESULTS

Current literature on the disorders of the eyelid is replete with useful clinical information of relevance to a practicing ophthalmologist. Major advances have been reported in understanding of the surgical anatomy and its applications, ptosis, entropion, ectropion, lagophthalmos, infection, inflammation, trauma, and tumors.

CONCLUSIONS

There seems to be tremendous excitement in revisiting the anatomy and pathology and modifying the management protocols and surgical procedures to achieve optimal results, as the subspecialty continues to advance at a brisk pace.