Electrical stimulation as a therapeutic option to improve eyelid function in chronic facial nerve disorders.
PURPOSE: To establish whether it is possible to improve orbicularis oculi muscle function in the eyelids of patients with a chronic seventh cranial nerve palsy by using transcutaneous electrical stimulation to the point at which electrical stimulation induces a functional blink. METHODS: Ten subjects (one woman, nine men) aged 36 to 76 with chronic, moderate to severe facial nerve palsy were recruited into the study. Voluntary and spontaneous eyelid movements were assessed, using an optical measuring system, before, during, and after a 3-month treatment period. Voluntary and spontaneous lid velocities were also measured and compared with eyelid kinematic data in normal subjects (12 women, 18 men; age range, 22-56 years). RESULTS: Therapeutic electrical stimulation applied over 3 months produced improvement in eyelid movement (>2 mm) in 8 of 10 patients during voluntary eyelid closure. However, there was no significant improvement recorded in spontaneous blink amplitudes or peak downward-phase velocity of the upper eyelid. This regimen of stimulation failed to recover function well enough that a functional blink could be induced in the paretic eyelid by electrical stimulation. CONCLUSIONS: Electrical stimulation using transcutaneous electrical nerve stimulators units can improve voluntary eye closure, apparently because of a reduction in stiffness of eyelid mechanics, rather than an improvement of muscle function. Investigation of alternative stimulation regimens is warranted. (+info)
Anticonvulsant-induced dyskinesias: a comparison with dyskinesias induced by neuroleptics.
Anticonvulsants cause dyskinesias more commonly than has been appreciated. Diphenylhydantoin (DPH), carbamazepine, primidone, and phenobarbitone may cause asterixis. DPH, but not other anticonvulsants, may cause orofacial dyskinesias, limb chorea, and dystonia in intoxicated patients. These dyskinesias are similar to those caused by neuroleptic drugs and may be related to dopamine antagonistic properties possessed by DPH. (+info)
MR imaging of Dejerine-Sottas disease.
We report the MR findings in two patients with clinically and histologically proved Dejerine-Sottas disease. One patient had spinal involvement with multiple thickened and clumped nerve roots of the cauda equina; the second had multiple enlarged and enhancing cranial nerves. Although these findings are not specific for Dejerine-Sottas disease, they are suggestive of the diagnosis, which is further corroborated with history and confirmed with sural nerve biopsy and laboratory studies. (+info)
MR appearance of rhinoscleroma.
BACKGROUND AND PURPOSE: We describe the MR imaging appearance of rhinoscleroma, an endemic, chronic, granulomatous disease whose causative agent is Klebsiella rhinoscleromatis. METHODS: The study included 15 patients (nine males and six females; mean age, 25 years; range, 13-36 years) with rhinoscleroma. MR imaging was performed in all patients. The signal intensity of the nasal masses was compared with that of fat, muscle, and CSF on both T1- and T2-weighted images. All cases were proved by histopathologic examination. RESULTS: The nasal masses were bilateral and symmetrical (n = 6), asymmetrical (n = 4), or unilateral (n = 5). They extended through the anterior nares (n = 9) or posterior choana into the nasopharynx (n = 3). They obstructed the ostiomeatal units with retained secretions in the related sinuses (n = 10). On T1-weighted images, rhinoscleroma showed striking (n = 9) or mild (n = 6) high signal intensity relative to muscle and CSF, but less hyperintensity than fat. On T2-weighted images, the nasal masses showed homogeneous high signal intensity (n = 10) or heterogeneous high signal intensity associated with hypointense foci (n = 5). They were hyperintense relative to fat and muscle, but less hyperintense than CSF. CONCLUSION: The hypertrophic stage of rhinoscleroma has characteristic mild to marked high signal intensity on both T1- and T2-weighted MR images. (+info)
The neuromuscular control of birdsong.
Birdsong requires complex learned motor skills involving the coordination of respiratory, vocal organ and craniomandibular muscle groups. Recent studies have added to our understanding of how these vocal subsystems function and interact during song production. The respiratory rhythm determines the temporal pattern of song. Sound is produced during expiration and each syllable is typically followed by a small inspiration, except at the highest syllable repetition rates when a pattern of pulsatile expiration is used. Both expiration and inspiration are active processes. The oscine vocal organ, the syrinx, contains two separate sound sources at the cranial end of each bronchus, each with independent motor control. Dorsal syringeal muscles regulate the timing of phonation by adducting the sound-generating labia into the air stream. Ventral syringeal muscles have an important role in determining the fundamental frequency of the sound. Different species use the two sides of their vocal organ in different ways to achieve the particular acoustic properties of their song. Reversible paralysis of the vocal organ during song learning in young birds reveals that motor practice is particularly important in late plastic song around the time of song crystallization in order for normal adult song to develop. Even in adult crystallized song, expiratory muscles use sensory feedback to make compensatory adjustments to perturbations of respiratory pressure. The stereotyped beak movements that accompany song appear to have a role in suppressing harmonics, particularly at low frequencies. (+info)
Features of cortically evoked swallowing in the awake primate (Macaca fascicularis).
Although the cerebral cortex has been implicated in the control of swallowing, the output organization of the cortical swallowing representation, and features of cortically evoked swallowing, remain unclear. The present study defined the output features of the primate "cortical swallowing representation" with intracortical microstimulation (ICMS) applied within the lateral sensorimotor cortex. In four hemispheres of two awake monkeys, microelectrode penetrations were made at 5 mm deep to the cortical surface corresponding to both the white matter underlying the CMA and the frontal operculum; EMG patterns of swallows elicited from these four cortical regions showed some statistically significant differences. Whereas swallowing ONLY was evoked at some sites, particularly within the deep cortical area, swallowing was more frequently evoked together with other orofacial responses including rhythmic jaw movements. Increasing ICMS intensity increased the magnitude, and decreased the latency, of the swallow-related EMG burst in the genioglossus muscle at some sites. These findings suggest that a number of distinct cortical foci may participate in the initiation and modulation of the swallowing synergy as well as in integrating the swallow within the masticatory sequence. (+info)
Direct injection of liposome-encapsulated doxorubicin optimizes chemomyectomy in rabbit eyelid.
PURPOSE: Doxorubicin chemomyectomy presently represents the only permanent, nonsurgical treatment for blepharospasm and hemifacial spasm. The major deterrent to an otherwise extremely effective treatment protocol is the development in patients of localized inflammation, discomfort, and skin injury over the injection site. As a potential alternative therapy, Doxil (Sequus, Menlo Park, CA), a liposome-encapsulated form of doxorubicin that displays tissue-selective therapeutic effects compared with free doxorubicin, was examined. These effects have been related to its increased retention in tissues and its sustained release over time. For the skin, Doxil is classified as an irritant rather than a vesicant. METHODS: Rabbits received direct injections of 1, 2, or 3 mg Doxil alone or in sequence with other agents directly into the lower eyelids. The treated eyelids were examined daily for signs of skin injury. One month after the last injection, the rabbits were euthanatized, and their eyelids were examined histologically for the effect of Doxil on the orbicularis oculi muscle and the skin. RESULTS: At equivalent milligram doses of free doxorubicin, Doxil spared the skin from injury. Doxil was only approximately 60% as effective in killing muscles as the same milligram dose of free doxorubicin. However, either two injections of Doxil spaced 2 months apart or preinjury of the lid with bupivacaine before a single dose of Doxil treatment resulted in increased muscle loss compared with a single dose of Doxil alone and was as effective as free doxorubicin. Higher doses of Doxil did not increase the desired myotoxic effect; apparently, the dose effect levels off at a maximum. Signs of skin injury were minimal; there were small or no adverse skin changes at the maximum effective myotoxic doses. CONCLUSIONS: Injection of Doxil resulted in significant reduction of skin injury compared with doxorubicin alone. Although single injections of Doxil were myotoxic, multiple exposure of the eyelid to the liposome-encapsulated form substantially improved myotoxicity while sparing the skin. Repeated doses of the liposome-encapsulated form of doxorubicin may be as clinically effective as free doxorubicin injections and may produce fewer unwanted side effects. (+info)
Differentiation of avian craniofacial muscles: I. Patterns of early regulatory gene expression and myosin heavy chain synthesis.
Myogenic populations of the avian head arise within both epithelial (somitic) and mesenchymal (unsegmented) mesodermal populations. The former, which gives rise to neck, tongue, laryngeal, and diaphragmatic muscles, show many similarities to trunk axial, body wall, and appendicular muscles. However, muscle progenitors originating within unsegmented head mesoderm exhibit several distinct features, including multiple ancestries, the absence of several somite lineage-determining regulatory gene products, diverse locations relative to neuraxial and pharyngeal tissues, and a prolonged and necessary interaction with neural crest cells. The object of this study has been to characterize the spatial and temporal patterns of early muscle regulatory gene expression and subsequent myosin heavy chain isoform appearance in avian mesenchyme-derived extraocular and branchial muscles, and compare these with expression patterns in myotome-derived neck and tongue muscles. Myf5 and myoD transcripts are detected in the dorsomedial (epaxial) region of the occipital somites before stage 12, but are not evident in the ventrolateral domain until stage 14. Within unsegmented head mesoderm, myf5 expression begins at stage 13.5 in the second branchial arch, followed within a few hours in the lateral rectus and first branchial arch myoblasts, then other eye and branchial arch muscles. Expression of myoD is detected initially in the first branchial arch beginning at stage 14.5, followed quickly by its appearance in other arches and eye muscles. Multiple foci of myoblasts expressing these transcripts are evident during the early stages of myogenesis in the first and third branchial arches and the lateral rectus-pyramidalis/quadratus complex, suggesting an early patterned segregation of muscle precursors within head mesoderm. Myf5-positive myoblasts forming the hypoglossal cord emerge from the lateral borders of somites 4 and 5 by stage 15 and move ventrally as a cohort. Myosin heavy chain (MyHC) is first immunologically detectable in several eye and branchial arch myofibers between stages 21 and 22, although many tongue and laryngeal muscles do not initiate myosin production until stage 24 or later. Detectable synthesis of the MyHC-S3 isoform, which characterizes myofibers as having "slow" contraction properties, occurs within 1-2 stages of the onset of MyHC synthesis in most head muscles, with tongue and laryngeal muscles being substantially delayed. Such a prolonged, 2- to 3-day period of regulatory gene expression preceding the onset of myosin production contrasts with the interval seen in muscles developing in axial (approximately 18 hr) and wing (approximately 1-1.5 days) locations, and is unique to head muscles. This finding suggests that ongoing interactions between head myoblasts and their surroundings, most likely neural crest cells, delay myoblast withdrawal from the mitotic pool. These descriptions define a spatiotemporal pattern of muscle regulatory gene and myosin heavy chain expression unique to head muscles. This pattern is independent of origin (somitic vs. unsegmented paraxial vs. prechordal mesoderm), position (extraocular vs. branchial vs. subpharyngeal), and fiber type (fast vs. slow) and is shared among all muscles whose precursors interact with cephalic neural crest populations. Dev Dyn 1999;216:96-112. (+info)