Abnormal extracellular material in the levator palpebrae superioris complex in congenital ptosis

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.

Surgical Observations of the Levator Aponeurosis Fibrotic Changes in Simple Congenital Ptosis Suggest Complex Pathogenesis

PURPOSE

To shed light upon the possible role of the levator aponeurosis (LA) developmental fibrotic changes as an added etiology for simple congenital ptosis, which causes limitation of the levator function (LF).

METHODS

This retrospective cohort study included patients with simple congenital ptosis who underwent skin approach LA resection as a primary intervention with an intraoperative photographic documentation of LA fibrotic changes. Preoperative demographics and clinical data were reviewed. The effect of LA fibrotic changes on the LF was assessed in different LA fibrotic changes with or without levator palpebrae superioris (LPS) muscle fatty infiltration.

RESULTS

A total of 56 eyelids of 49 patients with a mean age (±SD) 6.7 (±3.2) years were enrolled in this study. The fibrotic changes of LA were observed as a sheet of fibrosis (19 eyelids) or fibrous bands (23 eyelids). Fatty infiltration of LPS was noticed in 28 eyelids, either with or without fibrotic changes of LA. Preoperative LF was diminished in LPS fatty infiltration compared with LA fibrotic sheets (P = 0.026). Postoperative LF improved significantly in both LA fibrotic sheets and LA fibrotic bands (9.4 ± 2.5 mm and 9.6 ± 2.8 mm, respectively) compared with LPS with fatty infiltration (6.4 ± 1.8 mm) (P = 0.004).

CONCLUSIONS

Although our data are inconclusive due to lack of embryologic studies, the observed LA fibrotic changes may suggest a complex pathogenesis of simple congenital ptosis. The meticulous observation of the LA and the releasing of any adhesion or band to the surrounding structures could improve postoperative LF.

The Type and Content of Collagen Fibers of the Levator Aponeurosis in Patients With Simple Congenital Blepharoptosis

BACKGROUND

The pathogenesis of congenital blepharoptosis remains controversial and most of the studies focused on the histologic changes of the levator muscle. However, thickening of the aponeurosis was reported in congenital blepharoptosis. And the thickness of the levator aponeurosis was found to be correlated with the levator function in congenital dysmyogenic blepharoptosis.

PURPOSE

The authors conducted this research to investigate the histological changes of the levator aponeurosis of simple congenital blepharoptosis patients.

PATIENTS AND METHODS

The authors analyzed 12 levator aponeurosis from ptosis patients and 21 levator aponeurosis from the cadaver specimens without relative medical history. The specimens were stained with hematoxylin and eosin as well as Sirius red. The sections were examined under light-microscopy. The content and type of collagen fibers were examined with the photos taken of the sections stained with Sirius red under polarized light-microscopy.

RESULTS

The content and proportion of type I collagen increased significantly in the patient group compared with the cadaver group. The proportion of type I collagen was 97.5% in the patient group, while it was 51.5% in the cadaver group. However, no correlation was found either between the levator strength, degree of ptosis and the proportion of type I collagen in the patient group or between age, gender and proportion of type I collagen in the cadaver group.

CONCLUSIONS

To our knowledge, this is the first time this phenomenon was discovered. The increase of type I collagen in the levator aponeurosis of the simple congenital blepharoptosis patients may imply the increased stiffness and undermined ability of transmitting forces, dissipate energy and prevent mechanical failure in the levator aponeurosis.

Histological findings of levator muscle in unilateral congenital ptosis in different age groups

PURPOSE

To evaluate the different degree of muscle atrophy in specimens of levator muscle of patients operated on for unilateral congenital ptosis, as related to the age of the patient.

METHODS

Histological analysis of the specimen of the levator muscle of 29 patients who underwent a unilateral levator muscle resection under the care of one surgeon was performed. The study population was divided into two different groups according to the timing of surgery: group 1 included 15 children operated on at 2 to 4 years, and group 2 included 14 children operated on at 4.1 to 11 years.

RESULTS

Levator muscle of 12 patients of group 1 showed mild degree of muscle atrophy, with striated muscle fibres separated by thin fibrous septa incorporating groups of cells with peripheral nuclei and non-hyalinized cytoplasm (Masson's trichrome stain). In eight cases of group 2, levator muscle showed instead severe atrophy, with discontinuous striated muscle fibres separated by thick fibrous septa including cells with centralization of nuclei, hyalinization of cytoplasm (Masson's trichrome stain) and fatty infiltration.

CONCLUSION

Myofibres found in specimens of levator muscle following levator resection for congenital ptosis show characteristics of a degenerative process. This study seems to demonstrate that atrophy in the levator muscle appears to be related to the age of the patient at surgery, as atrophy tends to be more evident in older children with congenital ptosis.

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.

Eyelid Dysfunction in Neurodegenerative, Neurogenetic, and Neurometabolic Disease

Eye movement abnormalities are among the earliest clinical manifestations of inherited and acquired neurodegenerative diseases and play an integral role in their diagnosis. Eyelid movement is neuroanatomically linked to eye movement, and thus eyelid dysfunction can also be a distinguishing feature of neurodegenerative disease and complements eye movement abnormalities in helping us to understand their pathophysiology. In this review, we summarize the various eyelid abnormalities that can occur in neurodegenerative, neurogenetic, and neurometabolic diseases. We discuss eyelid disorders, such as ptosis, eyelid retraction, abnormal spontaneous and reflexive blinking, blepharospasm, and eyelid apraxia in the context of the neuroanatomic pathways that are affected. We also review the literature regarding the prevalence of eyelid abnormalities in different neurologic diseases as well as treatment strategies (Table 1).

Comparison between eyelid indices of ptotic eye and normal fellow eye in patients with unilateral congenital ptosis

PURPOSE

To evaluate the relationship between levator muscle function (LMF) and other eyelid parameters in the normal and affected eyes of patients with unilateral congenital ptosis.

METHODS

This study includes subjects with unilateral congenital upper lid ptosis who were referred for operation over a 2-year period. Patients with other eyelid abnormalities and previous eyelid surgery were excluded. Eyelid parameters including LMF, lid fissure height (LFH) and margin reflex distance (MRD) were measured in both eyes and analyzed.

RESULTS

A total of 77 patients with mean age of 26.4 ± 16.4 years were enrolled in the study. Mean LMF was 8.3 ± 4.6 mm in the ptotic and 13.1 ± 3.6 mm in the normal fellow eyes. Each millimeter of difference in LMF was associated with 0.30 mm of difference in LFH (95% CI: 0.25-0.35, P < 0.001) and 0.11 mm of difference in MRD of the ptotic eyes (95% CI: 0.08-0.12, P < 0.001) in the same direction. In addition, each millimeter of difference in LMF of ptotic eyes was associated with 0.48 mm of difference (95% CI: 0.33-0.62, P < 0.001) in LMF of non-ptotic eyes in the same direction.

CONCLUSION

A direct correlation was observed between LMF, and LFH and MRD in ptotic eyes which confirms the role of levator muscle dysfunction in the development of congenital ptosis and its severity. Furthermore, a direct correlation was also present between LMF of ptotic and non-ptotic eyes suggesting possible bilateral involvement in apparently unilateral congenital ptosis.

The Effect of Hering's Law on Different Ptosis Repair Methods

BACKGROUND

The Hering's law effect has significant importance in surgical planning and outcomes of eyelid surgery.

OBJECTIVES

The current study examined the preoperative and intraoperative effect of Hering's law in Mullerectomy and levator aponeurosis advancement.

METHODS

A retrospective analysis was conducted of 52 patients with unilateral ptosis who underwent surgical repair from January 2011 through June 2013. Patients underwent levator aponeurosis advancement or Mullerectomy with or without tarsectomy. Preoperative and postoperative clinical documentation and photographs were evaluated. Preoperative Hering's dependency and postoperative changes in positioning of the non-operated eyelid were measured. The decision to operate on the ptotic eye alone or on both eyelids was based on preoperative Hering's dependence and intraoperative changes in the contralateral eyelid.

RESULTS

Fifty-two patients with unilateral ptosis were included. Average age was 63.3 ± 20.1 years (range, 22-88 years; median, 61 years); 34 (65.4%) were female. The 14 cases that were not aponeurotic (either congenital, secondary to trauma, or due to postoperative ptosis) did not need contralateral repair (p = .000). In 4 (19%) cases of Mullerectomy and in 9 (52.9%) cases of levator advancement, both eyelids required surgery (p = .029). Hering's law effect was significantly more apparent in the levator advancement approach than in Mullerectomy.

CONCLUSIONS

Levator surgery resulted in a higher incidence of combined intraoperative and postoperative Hering's law effect than did Mullerectomy. Cases with poor levator function or congenital ptosis can be repaired unilaterally with no need for contralateral surgery. The fibrotic levator palpebrae muscle and its special innervations probably explain this phenomenon. This should be considered in surgical planning.

Is Hering's law as important in congenital blepharoptosis as in acquired ptosis?

BACKGROUND

Although Hering's law has significant importance in the planning and outcomes of eyelid surgery, it has not been applied in all cases of ptosis.

OBJECTIVES

The authors evaluate whether cases of unilateral congenital ptosis require surgery on the contralateral eyelid, in keeping with Hering's law.

METHODS

The records of 35 consecutive patients with unilateral congenital ptosis who had surgical repair between 2007 and 2012 were retrospectively analyzed. All patients underwent either levator resection or frontalis sling surgery. Preoperative and postoperative clinical documents and photographs were evaluated for each case, including preoperative Hering's dependence and postoperative measurements of the change in position of the nonoperated eyelid.

RESULTS

There were 19 women and 16 men, and the average patient age was 9.7 ± 10 years. The mean preoperative levator function and marginal reflex distance were 6.7 ± 4.7 mm and 0.3 ± 0.47 mm, respectively. There were significant differences in age, preoperative levator function, and marginal reflex distance between patients who underwent levator resection and those who had frontalis sling surgery. In all patients, the preoperative Hering's dependence of eyelid position did not show any decrease, and the position of the contralateral eyelid postoperatively did not differ from the baseline position.

CONCLUSIONS

This research shows that Hering's law does not apply to cases of congenital ptosis. This is likely due to the fibrotic levator palpebrae muscle and its special innervations. Thus, it is not necessary to perform levator resection or a frontalis sling operation on the unaffected eyelid.

The role of apoptosis in blepharoptosis

PURPOSE

The purpose of this study is to evaluate the role of apoptosis in the pathogenesis of blepharoptosis.

PATIENTS AND METHODS

Forty-five eyelids of 43 consecutive patients (16 female, 27 males) that underwent levator resection surgery for ptosis correction were included in the study. Twenty-six of the eyelids had congenital myogenic ptosis and 19 had aponeurotic ptosis. Levator palpebrae superioris function and height of the vertical palpebral fissure were measured in all patients. After levator resection surgery, the distal part of the levator aponeurosis was fixed and sent for evaluation. Apoptotic cells were detected using Apop Tag Plus Peroxidase In Situ Apoptosis Detection Kit.

RESULTS

The mean levator palpebrae superioris function was 8.4 mm (range 5-10 mm) in congenital ptosis group and 12.1 mm (range 10-17 mm) in the aponeurotic ptosis group. The mean height of the vertical palpebral fissure in patients with congenital ptosis and aponeurotic ptosis were 6.5 mm (range 5-9 mm) and 6.1 mm (3-9 mm), respectively. The mean apoptotic index of congenital ptosis and aponeurotic ptosis were 27.3 (16-39) and 29.8 (18-41), respectively. There was no statistically significant difference between congenital and aponeurotic ptosis groups in a mean apoptotic index (P<0.05). Apoptotic index was not correlated with age, levator palpebrae superioris function, palpebral fissure height, and lid crease height in two groups.

CONCLUSION

We found no statistically significant difference between two subtypes of blepharoptosis regarding apoptosis. According to this study, apoptosis seems to have no significant role in the development of aponeurotic blepharoptosis.

Incidence and demographics of childhood ptosis

PURPOSE

To report the incidence and demographics of childhood ptosis diagnosed over a 40-year period in a well-defined population.

DESIGN

Retrospective, population-based cohort study.

PARTICIPANTS

Patients (<19 years) diagnosed with childhood ptosis and residents of Olmsted County, Minnesota, from January 1, 1965, through December 31, 2004.

METHODS

The medical records of all potential patients identified by the Rochester Epidemiology Project were reviewed.

MAIN OUTCOME MEASURES

Calculated annual age- and gender-specific incidence rates and demographic information.

RESULTS

A total of 107 children were diagnosed with ptosis during the 40-year period, yielding an incidence of 7.9 per 100000 younger than 19 years (95% confidence interval [CI], 6.4-9.5). Ninety-six (89.7%) of the 107 had congenital-onset disease. Eighty-one (75%) of the 107 had simple congenital ptosis, yielding a birth prevalence of 1 in 842 births. A family history of childhood ptosis was present in 12% of queried patients with simple congenital ptosis. Three (4%) of the simple congenital ptosis cases were bilateral and 55 (68%) of the unilateral cases involved the left upper eyelid (95% CI, 57%-78%; P<0.001).

CONCLUSIONS

Childhood ptosis was diagnosed in 7.9 per 100000 patients younger than 19 years (95% CI, 6.4-9.5). Simple congenital ptosis was the most prevalent form, occurring in 1 in 842 births, and was significantly more likely to involve the left side.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Structural Abnormalities in the Levator Palpebrae Superioris Muscle in Patients With Congenital Blepharoptosis

BACKGROUND AND OBJECTIVE

To evaluate structural and ultrastructural abnormalities of the levator palpebrae superioris (LPS) complex in patients with congenital blepharoptosis.

PATIENTS AND METHODS

Samples of the LPS complex were obtained from patients operated on for congenital blepharoptosis between 2000 and 2001 and studied under light microscopy (15 cases) and electron microscopy (9 cases).

RESULTS

Findings of light microscopy evaluation of the LPS complex correlated closely with the clinical grading of congenital blepharoptosis-hypoplasia, decreased number and varying diameter of muscle fibers, and fibrous tissue hyperplasia in the endomysium and perimysium. The Müller's muscle preserved a normal appearance. Mild blepharoptosis revealed proliferation of collagen fibers on electron microscopy. Moderate blepharoptosis showed abnormal distribution of myofibrils and distortion of the tubular system and mitochondria in addition to the changes observed in mild blepharoptosis. Severe blepharoptosis showed mitochondria loss, cytoplasm thinning, and homogenous fiber areas in addition to the changes observed in mild and moderate blepharoptosis.

CONCLUSIONS

The clinical degree of severity of congenital blepharoptosis correlates positively with the degree of histopathologic changes in the levator palpebrae superioris muscle.

X linked dominant congenital isolated bilateral ptosis: the definition and characterisation of a new condition

AIMS

To characterise the inheritance of ptosis in one particular pedigree.

METHODS

The pedigree was analysed clinically and genetically to assess the mode of inheritance and to ascribe a gene locus for the condition.

RESULTS

Affected members of the pedigree have bilateral symmetrical congenital isolated ptosis, a condition which is linked to genetic markers on the X chromosome in this family.

CONCLUSION

A pedigree with dominantly inherited congenital bilateral ptosis is presented. The pedigree exhibits X linked dominant inheritance. A new ophthalmic condition was thereby characterised-namely, X linked dominant congenital isolated bilateral ptosis.

Levator palpebrae superioris fibre size in normals and patients with congenital ptosis

A study of the histochemical staining of levator palpebrae superioris (LPS) was undertaken to measure the muscle fibre size in normal individuals and in patients with congenital dystrophic ptosis in order to see whether there is an alteration in muscle fibre size in congenital ptosis. Eight LPS specimens were obtained: 4 from normal patients (3 from normal levator divided in a bilateral brow suspension procedure and 1 from an exenteration specimen) and 4 from levator resection procedures for treatment of unilateral congenital ptosis. Cryostat sections from these specimens were stained histochemically to reveal muscle fibre types. The orthogonal diameters were measuring using a computer-generated program and the two groups compared using the Mann-Whitney mu-test. No statistically significant difference in muscle fibre diameter was found between normals and patients with congenital ptosis. There was also no change in the distribution or range of muscle fibre diameter in patients with congenital ptosis. Our findings do not support the classification of congenital ptosis as a dystrophy.

Unilateral congenital ptosis with ipsilateral superior rectus muscle overaction

PURPOSE

Congenital ptosis may be accompanied by weakness of the ipsilateral superior rectus muscle. We report the finding of a hypertropia of the ipsilateral eye in patients with isolated unilateral congenital ptosis that became manifest only in upgaze.

METHODS

Seventy consecutive patients with congenital ptosis were recalled and 58 reexamined. Examination included assessment of visual acuities, palpebral apertures, levator muscle function, and an orthoptic examination. Particular attention was paid to the assessment of upgaze.

RESULTS

Thirty-eight patients had an isolated unilateral congenital ptosis. Four patients had bilateral ptosis, six had upgaze deficits, and ten others had a variety of other syndromes associated with ptosis. Seventeen of the 38 patients with isolated unilateral congenital ptosis were found to have an ipsilateral hypertropia on upgaze. The size of the vertical deviation varied from 5 to 30 prism diopters and, in the more severe cases, produced a cosmetic problem that became more noticeable after successful ptosis surgery. In one of these patients, a superior rectus muscle posterior fixation suture was effective in reducing the hypertropia.

CONCLUSION

Of a number of possible causes for the ipsilateral hypertropia in upgaze in patients with unilateral congenital ptosis that we observed either a misdirection syndrome within the superior division of the oculomotor nerve or an exaggerated Bell's reflex is the most likely.