Regenerative Failure Following Rat Neonatal Chorda Tympani Transection is Associated with Geniculate Ganglion Cell Loss and Terminal Field Plasticity in the Nucleus of the Solitary Tract.

Neural insult during development results in recovery outcomes that vary dependent upon the system under investigation. Nerve regeneration does not occur if the rat gustatory chorda tympani nerve is sectioned (CTX) during neonatal (≤P10) development. It is unclear how chorda tympani soma and terminal fields are affected after neonatal CTX. The current study determined the impact of neonatal CTX on chorda tympani neurons and brainstem gustatory terminal fields. To assess terminal field volume in the nucleus of the solitary tract (NTS), rats received CTX at P5 or P10 followed by chorda tympani label, or glossopharyngeal (GL) and greater superficial petrosal (GSP) label as adults. In another group of animals, terminal field volumes and numbers of chorda tympani neurons in the geniculate ganglion (GG) were determined by labeling the chorda tympani with DiI at the time of CTX in neonatal (P5) and adult (P50) rats. There was a greater loss of chorda tympani neurons following P5 CTX compared to adult denervation. Chorda tympani terminal field volume was dramatically reduced 50 days after P5 or P10 CTX. Lack of nerve regeneration after neonatal CTX is not caused by ganglion cell death alone, as approximately 30% of chorda tympani neurons survived into adulthood. Although the total field volume of intact gustatory nerves was not altered, the GSP volume and GSP-GL overlap increased in the dorsal NTS after CTX at P5, but not P10, demonstrating age-dependent plasticity. Our findings indicate that the developing gustatory system is highly plastic and simultaneously vulnerable to injury.

Evaluation of the early phase of Bell's palsy using 3 T MRI.

This prospective study on Bell's palsy investigated the value of 3 T MRI as a diagnostic tool to evaluate pathophysiological changes (i.e. edema) of facial nerve segments and the possibility to differentiate patients with high risk for incomplete recovery from patients who recover completely within 3 days after symptoms onset. For this institutional review board approved investigation, thirty patients (14 male, 16 female, mean age 44 years) with Bell's palsy underwent pre and postcontrast 3 T MRI of the cerebellopontine angle. T1-weighted imaging was performed (TR 20.0 ms, TE 2.46 ms, isotropic voxel size: 0.6 mm). Region-of-interest measurements were performed on the healthy and paralyzed side. To obtain normalized values, signal intensity increase percentage (SIIP) values were divided by contralateral results of the healthy side. Signal intensity measurements of examined nerve segments were compared using Wilcoxon and Mann-Whitney U tests and correlated to clinical findings categorized by the House-Brackmann score. The lesion side showed significantly higher signal intensities in the premeatal segment before and after contrast agent administration (P < 0.001). SIIP was highest in the premeatal segment compared to the geniculate ganglion (P < 0.001). Correlation analyses revealed no association between signal intensity measurements, clinical findings or early recovery rates after 3 months (P > 0.05). According to our results, early palsy-associated pathophysiological changes in the facial nerve premeatal segment might also be related to accumulation of proteins and not exclusively to edema. However, contrast agent enhancement quantification was not suitable as a diagnostic tool to distinguish different prognostic groups.

Hemangioma capilar de oído medio / Capillary hemangioma of the middle ear: a case report

Los hemangiomas capilares se consideran tumores vasculares benignos. Aproximadamente dos tercios de los mismos se localizan en cabeza y cuello. Su origen en oído medio procede del aporte vascular del ganglio geniculado. Se encuentran infradiagnosticados debido a la gran variedad de patologías con similares manifestaciones clínicas y radiológicas, siendo definitivo, el examen histológico para su diagnóstico(AU)

Capillary hemangiomas are considered benign vascular tumours. Two-thirds of hemangiomas occur in the head and neck region. They commonly originate from the vascular networks around the geniculate ganglion. They are underdiagnosed because there are a great many diseases with similar clinical and radiologic signs. Therefore, the histological exam is definitive for diagnosis(AU)

The amblyopic deficit and its relationship to geniculo-cortical processing streams.

Amblyopia or lazy eye is the most common cause of uniocular blindness in adults and is caused by a disruption to normal visual development as a consequence of unmatched inputs from the two eyes in early life, arising from a turned eye (strabismus), unequal refractive error (anisometropia), or form deprivation (e.g., cataract). Using high-field functional magnetic resonance imaging in a group of human adults with amblyopia, we previously demonstrated that reduced responses are observable at a thalamic level, that of the lateral geniculate nucleus (LGN). Here we investigate the selectivity of this deficit by using chromatic and achromatic stimuli that are designed to bias stimulation to one or other of the three ascending pathways (the parvocellular, magnocellular, and koniocellular). We find the greatest LGN deficit is for stimuli modulated along the chromatic, L/M cone opponent axis of color space, suggesting a selective loss of parvocellular function in the LGN. We also demonstrate a cortical deficit that involves all the visual areas studied (V1, V2, V3, VP, V3A, V4), and we find this is greatest for the two chromatic responses (S cone opponent and L/M cone opponent) versus the achromatic response, as might be expected from a loss of segregation of chromatic pathways in the cortex.

Initial lesions in Bell's palsy and Ramsay-Hunt syndrome.

CONCLUSION: The antidromic facial nerve response (AFNR) revealed that the initial lesion in both Bell's palsy and Hunt syndrome was mainly located around the geniculate ganglion within 1 week after onset of paralysis. The preoperative AFNR reflected the response near the initial lesion. OBJECTIVES: To review the initial lesion in Bell's palsy and Ramsay-Hunt syndrome using intraoperative monitoring of the AFNR. METHODS: 15 patients, including 8 with Bell's palsy and 7 with Ramsay-Hunt syndrome, were checked for the AFNR before and during transmastoid decompression surgery within 1 week after onset of paralysis. The AFNR monitoring was performed at the posterosuperior part of the anulus tympanicus preoperatively and at 4 points of the facial nerve during surgery. The nerve conduction block sites were diagnosed by the AFNR waveform. RESULTS: The monophasic wave revealing the block site was mainly observed at the geniculate ganglion in both diseases. The latencies of the preoperative responses corresponded to those recorded intraoperatively around the pyramidal segment of the facial nerve.

Facial palsy and fallopian canal expansion associated with idiopathic intracranial hypertension.

OBJECTIVE: Describe neurotologic findings associated with idiopathic intracranial hypertension (IIH). STUDY DESIGN: Retrospective. SETTING: Tertiary referral center. PATIENTS: Case of IIH (>250 mm water) presenting with unilateral facial palsy and enlargement of the fallopian canal on computed tomography and magnetic resonance imaging. INTERVENTION(S): Oral acetazolamide, corticosteroids, and cerebrospinal fluid drainage. MAIN OUTCOME MEASURE(S): Intracranial pressure measurement, cranial nerve examination, audiometry, and symptom assessment. RESULTS: Audiometry revealed asymmetric sensorineural hearing loss. Enlargement of the fallopian canal with cerebrospinal fluid was evident on imaging studies. Partial resolution of IIH symptoms was achieved. CONCLUSION: IIH is an enigmatic disease entity. Increased intracranial pressure usually presents with headache and pulsatile tinnitus and is occasionally associated with cranial neuropathies. Abducens palsy is most common, producing diplopia. Cranial nerve involvement is often asymmetric, producing false localizing signs. Facial paralysis is an uncommon sequela of IIH. Treatment of IIH consists of reducing intracranial pressure. Corticosteroids are recommended for treatment of facial paralysis.

Dystonin deficiency reduces taste buds and fungiform papillae in the anterior part of the tongue.

The anterior part of the tongue was examined in wild type and dystonia musculorum mice to assess the effect of dystonin loss on fungiform papillae. In the mutant mouse, the density of fungiform papillae and their taste buds was severely decreased when compared to wild type littermates (papilla, 67% reduction; taste bud, 77% reduction). The mutation also reduced the size of these papillae (17% reduction) and taste buds (29% reduction). In addition, immunohistochemical analysis demonstrated that the dystonin mutation reduced the number of PGP 9.5 and calbindin D28k-containing nerve fibers in fungiform papillae. These data together suggest that dystonin is required for the innervation and development of fungiform papillae and taste buds.

Bell's palsy with ipsilateral numbness.

Bell's palsy is an idiopathic facial palsy of the peripheral type. A herpes virus is the most likely mechanism. We report a patient with the often encountered combination of a facial palsy with ipsilateral sensory changes. Magnetic resonance imaging showed had contrast enhancement in the greater petrosal nerve. Viral spread through anatomical connections could be an explanation for the association of facial palsy with numbness.

Geniculate neuralgia: long-term results of surgical treatment.

A rare cause of otalgia is geniculate neuralgia. In its most typical form, it is characterized by severe paroxysmal neuralgic pain centered directly in the ear. The pain can be of a gradual onset and of a dull, persistent nature, but occasionally it is sharp and stabbing. When the pain becomes intractable, an operation to surgically excise the nervus intermedius and geniculate ganglion via the middle cranial fossa approach is indicated. The purpose of this article is to review the long-term outcomes in 64 patients who were treated in this manner. Findings indicate that excision of the nervus intermedius and geniculate ganglion can be routinely performed without causing facial paralysis and that it is an effective definitive treatment for intractable geniculate neuralgia.

Prevalence of HSV-1 LAT in human trigeminal, geniculate, and vestibular ganglia and its implication for cranial nerve syndromes.

Herpes simplex virus type 1 (HSV-1) enters sensory neurons and can remain latent there until reactivation. During latency restricted HSV-1 gene expression takes place in the form of latency-associated transcripts (LAT). LAT has been demonstrated to be important not only for latency but also for reactivation, which may cause cranial nerve disorders. Tissue sections of the trigeminal ganglia (TG), geniculate ganglia (GG), and the vestibular ganglia (VG) from seven subjects were examined for the presence of LAT using the in situ hybridization technique. LAT was found on both sides in allTG (100%), on both sides of five subjects (70%) in the GG, and in none of the VG. Using a second more sensitive detection method (RT-PCR), we found LAT in the VG of seven of ten other persons (70%). This is the first study to demonstrate viral latency in the VG, a finding that supports the hypothesis that vestibular neuritis is caused by HSV-1 reactivation. The distribution of LAT in the cranial nerve ganglia indicates that primary infection occurs in the TG and GG and subsequently spreads along the faciovestibular anastomosis to the VG.

Selective damage to either the "M" or "P" cell pathway in human retinal disease: implications for visual processing.

Studies in primates have shown there to be 2 main visual afferent pathways (magno and parvo) operating in parallel with different functional roles. Disease state may selectively affect one or other of these, as shown by particular sensory losses. In cases of treated Cuban tropical "neuropathy" (a retinopathy also occurs) visual acuity and achromatic contrast sensitivity are preserved although colour vision is severely affected indicating selective preservation of the "magno" pathway. In Melanoma Associated Retinopathy, red-green colour vision is preserved although achromatic contrast sensitivity for low spatial frequencies, and the detection of motion is damaged suggesting preferential damage to the "magno" pathway. Our studies illuminate two controversial aspects of the P and M systems: the role of type II parvocellular cells in colour vision and the role of M cells in detecting stimuli of low spatial and low temporal frequency.

Geniculate neuralgia and facial nerve sensory systems.

Although it is only a small ganglion, the geniculate ganglion subserves several different sensory systems with sensory fibers distributed to different parts of the head. The ganglion innervates chemoreceptors and phasic mechanoreceptors on the front of the tongue. In addition, the ganglion supplies mechanoreceptors of the hair follicles on the inner surface of the pinna and deep mechanoreceptors of nasal and buccal cavities. The ganglion also innervates chemoreceptors on the soft palate. No neurophysiological evidence was found for sensory innervation of the facial musculature. In considering neuralgias of geniculate ganglion origin, it is necessary to examine the loci of sensory projections of the ganglion and the possible effects of inflammation on pulse discharge patterns of sensory neurons.

Electrophysiologic evidence for normal optic nerve fiber projections in normally pigmented squinters.

The Siamese cat, a type of albino, has a visual pathway anomaly in which too many optic nerve fibers cross at the optic chiasm, and also frequently has strabismus. The correlation of strabismus with this defect suggests that a similar pathway defect without pigmentation anomalies, may be the cause of much human strabismus. Creel, Witkop, and King have used evoked potential methods to show that such a pathway defect likely occurs in the human albino. While unpublished control experiments verified their results on human albinos, no such defect has been found in the normally-pigmented human squinter. It is concluded that the visual pathway anomaly is limited to albinism and is not a likely cause of most human strabismus.