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Biomedical subjects

B R Frueh

Publications and source records attributed to B R Frueh.

At least 19 recordsLinked to original sources
PubMed2001

Differential section of the seventh nerve as a tertiary procedure for the treatment of benign essential blepharospasm.

PURPOSE: To examine the efficacy of differential section of the seventh nerve in treatment of patients with blepharospasm refractory to botulinum toxin and eyelid protractor myectomy. METHODS: A retrospective noncomparative interventional case series consisting of a cohort of 228 patients with benign essential blepharospasm followed from 1987 to 1997 in a university ophthalmic plastic surgery referral practice. Patients were treated with botulinum toxin injections, eyelid protractor myectomy, and differential section of the seventh nerve in stepwise fashion as needed for symptomatic control. RESULTS: Thirty-four patients (15% of total) underwent eyelid protractor myectomy during this period. Eyelid protractor myectomy failed to control blepharospasm in 7 (21%) of these 34 patients, who then underwent differential section of the seventh nerve an average of 2 years after myectomy. Patients were followed up for an average of 36 months, with a success rate of 42% (3 of 7). The remaining 4 patients had repeat differential section of the seventh nerve with a 50% success rate, which brought the overall success rate from differential section of the seventh nerve to 71%. Lower eyelid ectropion requiring surgical repair complicated 27% of differential section of the seventh nerve procedures. CONCLUSIONS: Differential section of the seventh nerve is a reasonable alternative in the treatment of patients who have persistent disability despite treatment with botulinum toxin injections and eyelid protractor myectomy.

Adult↗
PubMed2001

Specific force of the rat extraocular muscles, levator and superior rectus, measured in situ.

Extraocular muscles are characterized by their faster rates of contraction and their higher resistance to fatigue relative to limb skeletal muscles. Another often reported characteristic of extraocular muscles is that they generate lower specific forces (sP(o), force per muscle cross-sectional area, kN/m(2)) than limb skeletal muscles. To investigate this perplexing issue, the isometric contractile properties of the levator palpebrae superioris (levator) and superior rectus muscles of the rat were examined in situ with nerve and blood supply intact. The extraocular muscles were attached to a force transducer, and the cranial nerves exposed for direct stimulation. After determination of optimal muscle length (L(o)) and stimulation voltage, a full frequency-force relationship was established for each muscle. Maximum isometric tetanic force (P(o)) for the levator and superior rectus muscles was 177 +/- 13 and 280 +/- 10 mN (mean +/- SE), respectively. For the calculation of specific force, a number of rat levator and superior rectus muscles were stored in a 20% nitric acid-based solution to isolate individual muscle fibers. Muscle fiber lengths (L(f)) were expressed as a percentage of overall muscle length, allowing a mean L(f) to L(o) ratio to be used in the estimation of muscle cross-sectional area. Mean L(f):L(o) was determined to be 0.38 for the levator muscle and 0.45 for the superior rectus muscle. The sP(o) for the rat levator and superior rectus muscles measured in situ was 275 and 280 kN/m(2), respectively. These values are within the range of sP(o) values commonly reported for rat skeletal muscles. Furthermore P(o) and sP(o) for the rat levator and superior rectus muscles measured in situ were significantly higher (P < 0.001) than P(o) and sP(o) for these muscles measured in vitro. The results indicate that the force output of intact extraocular muscles differs greatly depending on the mode of testing. Although in vitro evaluation of extraocular muscle contractility will continue to reveal important information about this group of understudied muscles, the lower sP(o) values of these preparations should be recognized as being significantly less than their true potential. We conclude that extraocular muscles are not intrinsically weaker than skeletal muscles.

Animals↗
PubMed1999

Contractile activation characteristics of single permeabilized fibres from levator palpebrae superioris, orbicularis oculi and vastus lateralis muscles from humans.

1. We investigated the contractile activation characteristics of single membrane-permeabilized fibres from the following muscles from humans: the levator palpebrae superioris (LPS), an extraocular muscle; the orbicularis oculi (OO), a facial muscle; and the vastus lateralis (VL), a major muscle of the thigh. 2. Single permeabilized muscle fibres were isolated from each of the different muscles, attached to a sensitive force transducer and activated by rapid immersion in buffered solutions of varying [Ca2+] and [Sr2+]. Fibres were allocated into discrete populations based on their contractile characteristics, including their differential force responses during Ca2+ and Sr2+ activation. 3. With the exception of one fibre from the LPS, all 152 fibres sampled from the three different human muscles could be classified into either population I (slow, type I) or population II (fast, type II) based on their force-pCa(pSr) relations. The LPS muscle fibre which was unable to be classified into the two major fibre populations displayed a combination of the typical force-pCa(pSr) relations for mammalian fast and slow muscle fibres. 4. Although fibres from the LPS, OO and VL muscles had similar differential sensitivities to Ca2+and Sr2+, the steepness of the force-pCa(pSr) curves for fibres from the LPS and OO muscles were highly variable compared with those for fibres from the VL muscle. Specific forces (N cm-2) of the smaller diameter fibres from the LPS and OO muscles were significantly lower than those of fibres from the VL muscle. 5. The differences in the contractile activation characteristics between fibres from the VL muscle and those of fibres from facial (OO) muscles and extraocular (LPS) muscles, reflect the differences in their fibre composition that are responsible for their functional specificity.

Algorithms↗
PubMed1997

Mucoepidermoid carcinoma of the caruncle.

PURPOSE: To report a case of mucoepidermoid carcinoma, a highly aggressive variant of conjunctival squamous cell carcinoma. METHODS: We examined and treated a 57-year-old man with mucoepidermoid carcinoma of the caruncle, a highly unusual site for this tumor. RESULTS: In the past, simple excision of this tumor has been followed by rapid recurrence. Our patient underwent wide surgical excision of the tumor and has shown no evidence of recurrence after 16 months of follow-up. CONCLUSION: Mucoepidermoid carcinoma may first manifest in the caruncle. Histologically verified, tumor-free surgical margins are necessary for complete excision.

Carcinoma, Mucoepidermoid↗
PubMed1996

Angiosarcoma metastatic to the orbit.

Angiosarcoma is a rare malignant endothelial cell tumor. Few reports of primary orbital angiosarcoma exist in the literature. A 46-year-old woman had a 3-month history of progressive diplopia and right-sided exophthalmos. Magnetic resonance imaging showed a right intraconal mass, consistent with a cavernous hemangioma. Ultrasound examination showed a isolated mass with moderate vascularity, consistent with a metastatic lesion. Subtotal excision through a lateral orbitotomy was performed. Tissue was stained with hematoxylineosin, periodic acid-Schiff, and immunohistochemical stains for factor-VIII-related antigen and Ulex europaeus agglutinin I lectin. Lateral orbitotomy biopsy specimens showed an angiosarcoma, similar to a primary breast angiosarcoma that had been resected 2 years previously. The patient initially underwent orbital exenteration for her only known metastasis. Despite a multidisciplinary and aggressive approach to this tumor, the tumor recurred, and the patient died.

Breast Neoplasms↗
PubMed1996

Evaluation of levator muscle integrity in ptosis with levator force measurement.

PURPOSE: To determine the efficacy of the force the levator muscle can generate as a diagnostic tool for ascertaining the cause of ptosis. METHODS: A total of 187 patients with ptosis were evaluated clinically, their levator force was measured, and each ptotic eyelid subsequently had surgical correction. At each step, patients received a diagnosis of congenital or acquired (history- dependent) aponeurotic, myogenic, neurogenic, or mechanical ptosis. To measure the levator force, a clamp placed on the upper eyelid lashes was attached to a force transducer. The maximum force generated on upgaze was recorded as the levator force. Data from healthy subjects were used to determine whether each levator muscle of the ptotic eyelids produced normal or less than normal force. The correct diagnosis was considered to be the diagnosis based on the findings at the time of surgery. The diagnosis of each patient with ptosis determined by eyelid excursion, eyelid excursion plus examination, levator force, and the levator force plus examination results were compared with the correct diagnosis. RESULTS: Eyelid excursion predicted the correct diagnosis 78.2% of the time. When eyelid excursion was combined with the examination results, the diagnosis was correct 84.0% of the time. Levator force predicted the correct diagnosis 95.2% of the time. When levator force was combined with the examination, the diagnosis was correct 97.9% of the time. CONCLUSION: Diagnosis of the cause of ptosis based on levator force measurement is significantly more accurate than when the diagnosis is based on eyelid excursion, even when information obtained on examination also is considered. Levator force measurement should be an integral part of ptosis evaluation.

Adolescent↗
PubMed1995

Evaluation and clinical significance of the mechanical properties of various palpebral springs.

Fourteen different wire materials were evaluated for use as palpebral springs. Three of these, stainless steel 0.010- and 0.012-in diameter, respectively, and Australian stainless steel 0.012-in diameter, fulfilled the designated criteria for suitability. The physiologic deflection range of palpebral springs was determined by examining 20 normal individuals. Angles that a spring would subtend were measured with eyes closed (42 +/- 3 degrees), in primary position (20 +/- 3 degrees), and in upgaze (6 +/- 3 degrees). The effects of spring design on load-deflection (the force required for angular deflection) were evaluated for 0.010- and 0.012-in stainless steel wire within the physiologic deflection range. Variations in spring design in addition to wire diameter (gauge) included alteration of external loop size, number of external loop coils, and resting spring angle. There was a direct linear relationship between force and angular deflection (load-deflection). Larger wire diameter increased the load-deflection. Australian stainless steel had a higher load deflection (stiffer) for a given gauge than regular stainless steel. Smaller diameter external loops and fewer external loop coils increased load-deflection. Although definite conclusions could not be drawn regarding the effect of resting angle on load-deflection, it appeared that no relationship (zero correlation) existed over the angles tested (55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees). These findings were consistent with predictions based on standard spring equations. The clinical significance of the findings is discussed with reference to surgical planning and evaluation of lid dynamics.

Adolescent↗
PubMed1995

Intraorbital wood foreign body.

It is frequently difficult to identify and localize organic intraorbital foreign bodies despite modern day high-resolution imaging studies. Although there can be grave complications associated with retention of organic intraorbital foreign bodies, many believe that removal of such bodies in most cases is unwarranted. A high clinical suspicion, proper choice of imaging studies, and removal by a skilled orbital surgeon probably make the risk of surgical exploration and foreign body removal less than the risk of foreign body retention. We present a case of an intraorbital wood foreign body that required two separate explorations for retrieval. An initial intraconal exploration failed to locate the foreign body. Although the clinical suspicion was high, the imaging studies were equivocal, complicating the management. A second exploration yielded a large intraorbital wooden foreign body in the inferior extraconal space. The patient fully recovered and regained visual acuity of 20/20. The evaluation of such patients and details of management strategy are discussed.

Child↗
PubMed1995

Elastic modulus of orbicularis oculi muscle in normal humans, humans with Graves' eye disease, and cynomolgus monkeys.

We built an experimental apparatus to investigate the passive elastic characteristics of orbicularis oculi muscle and examined specimens from normal humans, humans with stable Graves' eye disease, and cynomolgus monkeys. Stress-strain curves were determined and found to be exponential. The elastic modulus (Young's modulus), analogous to the stiffness of the material, was calculated as a function of strain. Elastic modulus as a function of instantaneous stress was linear. Monkey elastic modulus values were determined, but did not allow meaningful interspecies comparison because of the small sample size. No significant difference was found between normal humans and humans with Graves' eye disease with respect to elastic modulus values.

Animals↗
PubMed1995

Microdeletion of chromosome 7P syndrome ocular manifestations.

Several syndromes have been associated with microdeletions of the autosomes. These syndromes are diverse in their morphology and frequently manifest abnormalities of the ocular adnexa. A child with an uncommon microdeletion of the short arm of chromosome 7P presented initially with congenital myogenic ptosis. After multiple systemic abnormalities were found during a routine examination, the child was referred for genetic evaluation where the defects were incidentally found. The child responded well with a fascia lata frontalis sling. The genetic disorder is discussed with an emphasis on the ophthalmologic findings.

Abnormalities, Multiple↗
PubMed1995

Carotid-cavernous fistula mimicking Graves' eye disease.

We encountered two patients referred for treatment of Graves' eye disease who had atypical features and were found to have carotid-cavernous fistulae. The relevant clinical findings and investigations used to make this important distinction are described, and the factors involved in the initial diagnostic confusion are analyzed. A correct diagnosis leading to proper treatment was made once atypical features were taken note of and alternative diagnoses considered, despite the context of presumed Graves' eye disease. We conclude that these two entities are quite different but have enough similarities to overlap in certain clinical contexts.

Aged↗
PubMed1994

Contractile properties and temperature sensitivity of the extraocular muscles, the levator and superior rectus, of the rabbit.

1. Contractile and fatigue-resistance characteristics, temperature sensitivity (10-37 degrees C) of contraction, and histochemical fibre types were determined for two of the extraocular muscles, the superior rectus and levator palpebrae superioris (levator), of the rabbit. 2. The levator displayed similar contractile characteristics (time to peak, half-relaxation time of twitch response, and twitch-tetanus force ratio) to mammalian fast-twitch limb muscle at room temperature (20 degrees C). However, normalized twitch and tetanic force levels were significantly less than those found in limb muscle. The superior rectus displayed the characteristics of even faster contraction than the levator at 20 degrees C, but generated lower maximum force levels than the levator. 3. The twitch response of the superior rectus showed a biphasic relaxation phase. This response was not due to non-twitch (tonic) fibres present in the superior rectus as it was unaffected by propranolol application during muscle stimulation. 4. The superior rectus and levator displayed significantly less fatigue in the tetanic force response than fast-twitch limb muscles did in response to a fatiguing electrical stimulation protocol. The levator was significantly more fatigue resistant than the superior rectus. 5. The force responses of both extraocular muscles displayed a similar dependence on temperature (10-37 degrees C) to limb skeletal muscles. 6. The superior rectus and levator exhibited a high proportion of fast-twitch muscle fibres (type II) as shown by myosin ATPase staining. Succinate dehydrogenase activity indicated that these muscles showed a high oxidative capacity, with a staining intensity typical of type I or type II A fibres of limb muscles. 7. The results emphasize the morphological and functional complexity of mammalian extraocular muscles. The combination of very fast contractile properties with high oxidative capacity make these muscles well suited to their role in eye/eyelid movement.

Animals↗
PubMed1994

Contractile properties of single skinned fibres from the extraocular muscles, the levator and superior rectus, of the rabbit.

1. The superior rectus and levator palpebrae superioris (levator), two of the extraocular muscles, were dissected from the rabbit and stored in a glycerol-based solution at -20 degrees C in order to prepare single, skinned fibres. 2. The Ca(2+)- and Sr(2+)-activated isometric contractile properties were determined for individual extraocular muscle fibres. Fibres were separated into discrete groups or fibre types on the basis of their physiological characteristics. The superior rectus and levator muscles were both found to consist of fibres which exhibited similar contractile characteristics to fast- and slow-twitch fibres from other mammalian muscle, including type I, type IIA and type IIB fibres. 3. As well as the existence of the normal, classical fibre types in extraocular muscle there were also a large number of fibres from both muscles which exhibited mixed fast- and slow-twitch contractile characteristics within the single contracting unit. Of the fibres sampled, the mixed fibres comprised the second largest population (7/19, 37%) in the levator and the largest fibre population in the superior rectus (11/31, 35.5%). These results are consistent with histochemical and immunohistochemical reports in the literature which suggest the co-existence of fast and slow myosin along the length of the extraocular muscle fibres. 4. Extraocular muscle fibres exhibited lower absolute maximum forces compared with other mammalian limb muscle fibres. However, when corrected for fibre cross-sectional area, the maximum tension development was within the normal range for mammalian limb muscle fibres, except for one group (type IIA) of fast-twitch fibres which exhibited significantly lower maximal tension. 5. The existence of a large proportion of fibres with composite fast- and slow-twitch characteristics highlights the functional and morphological complexity of these muscles. It is postulated that the functional significance of these mixed fibres may be to provide or enhance the resolution for subtle, precise movements of the eye and eyelid.

Animals↗
PubMed1994

Measurements of upper eyelid and eyebrow dimensions in healthy white individuals.

Facial appearance is influenced by the anatomic relationship of the eyebrow and eyelid, and surgical procedures on these structures attempt to restore or preserve not only symmetry but also normal appearance. To provide useful benchmarks for such interventions, we measured the eyebrow height, upper eyelid crease height, and amount of visible pretarsal skin of 143 white subjects who had no facial abnormalities. An age effect was observed for all measures, indicating a direct relationship with age until the middle age range (41 to 60 years), when mean estimates leveled off or decreased somewhat relative to younger age groups. Within the 41- to 60-year age group, for example, the average (S.D.) values for pretarsal skin height, eyelid crease height, and eyebrow height were 1.4 mm (1.1 mm), 6.4 mm (1.2 mm), and 6.4 mm (1.8 mm), respectively. Eyebrow and pretarsal skin heights were greater in females than males, and eyelid crease height showed similar gender-related trends. With increasing age, variation around the mean estimates for eyelid and eyebrow measurement increased, which may be indicative of variability across individuals in the physiologic response to the aging process. As expected, a high degree of intereye correlation was observed (correlation coefficients of 0.87 to 0.96). These results emphasize the importance of providing a normal anatomic relationship that relates to the patient's age and gender, as well as an outcome that is symmetric, in corrective or cosmetic procedures on the eyelid and eyebrow.

Adolescent↗
PubMed1992

Effects of eyelid protractor excision for the treatment of benign essential blepharospasm.

Data were analyzed from 37 patients with essential blepharospasm who had undergone upper eyelid protractor excision with brow suspension, and who had a median follow-up of 40 months (range, 12 to 83.5 months) after surgery. Of the 37 patients, 15 (40.5%) had sufficient relief of their spasms at their last follow-up; 22 patients (59.5%) had functionally significant recurrent or residual spasms after upper eyelid surgery. Of these 22 patients, 12 (55%) had recurrences more than six months after surgery, and four patients (18%) had recurrences more than one year after surgery. Patients with Meige syndrome were no more likely to experience recurrent spasms after upper eyelid surgery than patients who lacked a lower facial spasm component. Recurrence of symptoms was primarily the result of lower eyelid spasms in 11 patients (50%), upper eyelid spasms in one patient (5%), and all eyelids in six patients (27%). The location of recurrent spasms could not be ascertained in four patients (18%), with whom we had only telephone contact. Seven of 12 patients (58%) undergoing secondary procedures had relief from their spasms at the end of this study. Excluding those patients who chose to decline further surgery, 22 of 27 patients (81.5%) received satisfactory relief of symptoms after upper eyelid and, if needed, lower eyelid and repeat upper eyelid protractor excision. These long-term results are comparable to those reported previously for differential section of the facial nerve. Because the side effects of eyelid protractor excision are generally more acceptable, we recommend that when surgery is determined to be necessary for essential blepharospasm, upper eyelid protractor excision is the preferred surgical approach.

Aged↗