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Results for “GENICULATE GANGLION”

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PubMed1989

Intratemporal vascular tumors: detection with CT and MR imaging.

The diagnostic contributions of computed tomography (CT) and magnetic resonance (MR) imaging were compared in 12 patients with benign intratemporal vascular tumors (hemangioma or vascular malformation). The tumors included six in the internal acoustic canal and six in the geniculate ganglion region. Clinical and histologic correlations were made. Two of the six patients with tumors in the internal acoustic canal underwent CT, and both required gas cisternography to show the tumor. Five patients in that group underwent MR imaging, and all five studies showed the tumor. All six patients with geniculate ganglion tumors underwent CT. Results in one study were questionable, and five showed the tumor. Five patients in this group underwent MR imaging, but the MR findings were positive in only two cases. MR imaging should therefore be performed before CT in the evaluation of facial nerve dysfunction, as it demonstrated all tumors in the internal acoustic canal and some in the geniculate ganglion region. If MR findings are negative, CT should then be performed to rule out a possible geniculate ganglion lesion.

Adult↗

PubMed1997

Intratemporal facial nerve blood flow in guinea pigs.

HYPOTHESIS: To investigate the effect of interruption of the stylomastoid artery and the petrosal artery on the facial nerve blood flow with the use of a laser Doppler flowmeter. BACKGROUND: Ischemia of the facial nerve is thought to be one of the most possible causes in idiopathic facial palsy. The blood supply in the facial nerve has been studied morphologically in considerable detail; however, we have little information on its hemodynamics. METHODS: The animals used were 20 guinea pigs. The blood flow in the facial nerve at the geniculate ganglion was measured using a laser Doppler flowmeter, and the change in the facial nerve blood flow between before and after interruption of the stylomastoid artery and the petrosal artery was investigated. The interruption of both arteries was carried out by electrical cauterization with a bipolar coagulator. RESULTS: Interruption of the petrosal artery resulted in almost complete ischemia of the facial nerve at the geniculate ganglion. This decrease in the facial nerve blood flow was significant statistically (p < 0.001). But, interruption of the stylomastoid artery caused no change. CONCLUSIONS: The blood flow in the geniculate ganglion of the facial nerve is thought to come not from the stylomastoid artery but mainly from the petrosal artery. Peripheral facial palsy following ligation of the middle meningeal artery or embolization of the maxillary artery or intra-arterial infusion of anticancer drug into the maxillary artery is likely to be attributed to facial nerve ischemia at the level of the geniculate ganglion.

Animals↗

PubMed1991

Relationship between response latency and amplitude for ganglion and geniculate X- and Y-cells in the cat.

This study investigates the relationship between visual response latency and amplitude in the retina and dorsal lateral geniculate nucleus (dLGN) of the anesthetized, paralyzed cat. The discharge rate profiles of retinal ganglion and dLGN X- and Y-cells were measured on a trial by trial basis during repeated stimulation with sinusoidal grating patterns. Latencies of response onsets and peaks were regressed linearly against different measures of response amplitude to determine the extent of covariance. In general, response amplitude was a poor predictor of response latency for both retinal ganglion and geniculate cells. The results suggest that response latency, which changes systematically with stimulus spatial frequency and/or contrast, is not a trivial consequence of discharge rate at either level of the visual system.

Animals↗

PubMed1997

Contrast enhancement of the facial nerve on MRI: normal or pathological?

We prospectively analysed the normal contrast-enhanced MRI features of the facial nerve and determined criteria for pathological contrast enhancement. We studied 31 patients with clinically normal facial nerves with T1-weighted images before and after contrast medium. The intensity, thickness and right-left symmetry of enhancement were assessed in each segment and correlated with MRI features observed in abnormal facial nerves. Enhancement along at least one segment of the facial nerve was seen in 98% of cases, but only within the facial canal: labyrinthine segment: 78.2%; geniculate ganglion: 96.9%; tympanic: 88.4%; mastoid: 66.6%. Marked (+2) to intense (+3) enhancement was seen in the labyrinthine segment in 17.4%, the geniculate ganglion in 36.3%, and the tympanic (25.6%) and mastoid (7.1%) segments, whereas intense enhancement was only seen in the geniculate ganglion (6%) and the tympanic segment (11.6%). A right-left asymmetry was noted in 69% of cases. No correlation was found between enhancement and the thickness of the nerve. No enhancement of the eighth nerve was seen. We suggest three criteria for pathological enhancement: enhancement outside the facial canal; extension of enhancement to the eighth nerve; and intense enhancement in the labyrinthine and/or mastoid segments.

Adolescent↗

PubMed1991

Hemangioma of the facial nerve: role of the geniculate capillary plexus.

Hemangioma of the facial nerve may occur more frequently than previously recognized. This benign vascular tumor most often arises in the area of the geniculate ganglion, although the reason for this site of predilection is not known. Using silicon injection and cross-sectional vessel counts, we recently demonstrated the presence of a geniculate capillary plexus (GCP) in the cat. The present study was designed to identify a similar GCP in man, if present, and to relate if to the site of predilection of hemangioma of the facial nerve. Twenty-five human facial nerves were studied in horizontally sectioned temporal bones. A clinical case of hemangioma arising at the geniculate ganglion is presented. The human geniculate ganglion has a very rich capillary plexus in contrast to the poor intrinsic vasculature of the adjacent labyrinthine segment and nioderate vasculature of the tympanic segment of the facial nerve. We hypothesize that the GCP is the origin of most hemangiomas of facial nerve. The anatomic distinctness of the geniculate gangion and GCP from the facial nerve may allow removal of these tumors with preservation of motor function in certain cases.

Journal Article↗

PubMed1990

Murine strain differences in taste responsivity and organization of the rostral nucleus of the solitary tract.

Taste responsivity and organization of fungiform papillae, geniculate ganglion neurons and gustatory recipient zones of the nucleus of the solitary tract (NST) were examined in C57BL/6NCrlBR (C57) mice, BALB/c6NCrlBR (BALB/c) mice and CB6F1/CrlBr (CB6) mice, an F1 hybrid cross between BALB/c and C57 mice. Results from behavioral studies confirm that C57 and CB6 mice exhibit higher preferences to sucrose and lower preferences to NaCl, as compared to BALB/c mice. No strain differences were confirmed for aversion responses to citric acid or quinine HCl taste stimuli. Anatomical analyses show that the number and organization of fungiform papillae do not reliably differ between C57, BALB/c, and CB6 mice, nor do volumes of glossopharyngeal terminal fields in the NST. However, strain-specific differences exist in the number of neurons contained in the geniculate ganglion, volume of chorda tympani (CT) terminal fields in the rostral NST, and number of NST neurons contained in CT terminal fields. BALB/c and CB6 mice possess a greater number of geniculate ganglion neurons and larger CT terminal fields, as compared to C57 mice. However, strain differences in the number of geniculate ganglion neurons and terminal field volume are not obviously correlated with strain differences in gustatory responsivity. The only reliable relationship confirmed between taste responsivity and neuroanatomical organization of the rostral NST relates to the absolute number of neurons contained in CT terminal fields, and corresponding neuronal density within CT terminal fields. Chorda tympani terminal fields of C57 and CB6 mice contain an average of 379 neurons, whereas CT terminal fields of BALB/c mice contain an average of 531 neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Contrast-enhanced MR of the facial nerve in patients with posttraumatic peripheral facial nerve palsy.

PURPOSE: To estimate the value of noncontrast and contrast-enhanced T1-weighted MR imaging in detecting the underlying mechanisms of injury and regeneration in immediate- or delayed-onset posttraumatic peripheral facial nerve palsy. METHODS: Twenty-four patients with posttraumatic peripheral facial nerve palsy were examined on a 1.5-T MR imaging unit with precontrast and postcontrast T1-weighted spin-echo and gradient-echo sequences. RESULTS: Abnormal enhancement of the distal intrameatal nerve segment was visible in 92% of the patients up to 2 years after their initial trauma. A hematoma within the geniculate ganglion was seen in 33% of the patients with a longitudinal fracture. The greater superficial petrosal nerve (in 32% of patients) and the geniculate ganglion (in 48% of patients) were thick and intensely enhancing. Hematoma within the cochlea/vestibule or enhancement of the cochlea/vestibule and the vestibulocochlear (eighth) nerve was observed in transverse fractures. CONCLUSION: MR images can show long-lasting abnormal nerve enhancement, especially in the distal intrameatal nerve segment, related to the long-lasting breakdown of the blood/peripheral nerve barrier associated with nerve degeneration and regeneration after traumatic stretching of the greater superficial petrosal nerve. Additionally, intraoperatively observed perineural and intraneural scar formation leads to thickening and intense enhancement of the affected nerve segments on MR images. A hematoma in the region of the geniculate ganglion can be seen in some but not all patients. Associated damage of the inner ear structures in patients with transverse fractures is also visible on MR images.

Adolescent↗

PubMed2000

Evidence for nitroxidergic innervation in monkey ophthalmic arteries in vivo and in vitro.

In anesthetized monkeys, electrical stimulation (ES) of the pterygopalatine or geniculate ganglion dilated the ipsilateral ophthalmic artery (OA). The induced vasodilatation was unaffected by phentolamine but potentiated by atropine. Intravenous N(G)-nitro-L-arginine (L-NNA) abolished the response, which was restored by L-arginine. Hexamethonium-abolished vasodilator responses induced solely by geniculate ganglionic stimulation. The L-NNA constricted OA; L-arginine reversed the effect. Destruction of the pterygopalatine ganglion constricted the ipsilateral artery. Helical strips of OA isolated under deep anesthesia from monkeys, denuded of endothelium, responded to transmural ES with relaxations, which were abolished by tetrodotoxin and L-NNA but were potentiated by atropine. It is concluded that neurogenic vasodilatation of monkey OA is mediated by nerve-derived nitric oxide (NO), and the nerve is originated from the ipsilateral pterygopalatine ganglion that is innervated by cholinergic neurons from the brain stem via the geniculate ganglion. The OA appears to be dilated by mediation of NO continuously liberated from nerves that receive tonic discharges from the vasomotor center. Acetylcholine liberated from postganglionic cholinergic nerves would impair the release of neurogenic NO.

Animals↗

PubMedDate not supplied

Management of facial paralysis in temporal bone fractures: a prospective study analyzing 11 operated fractures.

OBJECTIVE: This study was instituted to evaluate patients operated on for traumatic facial paralysis. STUDY DESIGN: A prospective study and literature review. MATERIALS AND METHODS: Between 1996 and 2001, 10 patients with 11 temporal bone fractures resulting in facial paralysis, who were treated by surgical exploration, were handled. One patient had bilateral facial paralysis because of a bilateral temporal bone fracture. All patients had immediate facial paralysis after trauma. The sample included 7 males and 3 females, aged between 8 and 43 years. RESULTS: Of the 11 fractures, 7 (63%) were longitudinal and 4 (37%) were mixed type. There were no transverse fractures. The longitudinal fractures were operated on by the middle cranial fossa (MCF) approach, whereas the mixed fractures were operated on by using a combined approach, consisting of both MCF and transmastoid approaches. The first neurotologic examination and electrophysiological evaluation of the patients were carried out at the earliest 5 days and at the latest 50 days (mean, 25.6 days). The decision for surgery based mainly on electroneurography (ENoG) was possible only in one fracture. In the remaining 10 fractures, the decision for surgery was based mainly on the high-resolution computed tomography (HRCT), taking into account that electromyography (EMG) showed no regeneration potentials. The timing of the surgical intervention ranged from 14 to 75 days (mean, 37.9 days). During the operation, fibrosis at the geniculate ganglion was seen in 5 fractures, impingement of the facial nerve by bone spicules at the geniculate ganglion in 2 fractures, disruption or laceration at the origin of major superficial petrosal nerve also in 2 fractures, and edema around the geniculate ganglion, which is considered a mild form of injury, seen in only 2 fractures. Five fractures showed House-Brackmann (HB) grade 1, 4 patients showed HB grade 2, and 2 patients showed HB grade 3 facial recovery. There were no hearing deterioration or permanent complications related with the procedures. CONCLUSIONS: It is rarely possible to see the patients with traumatic facial paralysis in the early period and thus to perform ENoG in the critical 6 days after facial paralysis. HRCT, with the contribution of EMG and clinical judgment, has the greatest impact in decision making in patients seen late. On the basis of the facial outcomes observed in the present prospective surgical series, the recovery of satisfactory facial nerve function could be achieved, regardless of timing of surgery performed, within the first 3 months after the onset of paralysis. This study demonstrates that unless there is a disruption of the main trunk, necessitating primary end-to-end anastomosis or grafting, the type of injury does not have any clear effect on the facial outcome, as long as appropriate surgical management is applied.

Adult↗

PubMedDate not supplied

Familial dysautonomia (Riley-Day syndrome). Temporal bone findings and otolaryngological manifestations.

Familial dysautonomia, or Riley-Day syndrome, is inherited in an autosomal recessive fashion and occurs almost exclusively in Jewish families. This disorder is characterized by a smooth tongue devoid of fungiform papillae and of taste buds, and is clinically associated with poor taste discrimination. An unsteady gait and dizziness on change in position are also common presenting symptoms. This study reports the histopathological findings of eight temporal bones from four patients with documented familial dysautonomia. For the control series, 13 normal temporal bones were also studied. The most striking finding in the dysautonomic patients was an extreme paucity of geniculate ganglion cells (P less than 0.001). A statistically significant reduction in the number of neurons was also found both in the superior and in the inferior divisions of the vestibular nerve (P less than 0.001). The paucity of the geniculate ganglion cells correlates well with the impairment of the taste in dysautonomic individuals, since the afferent fibers leaving taste buds of the anterior two-thirds of the tongue run via the chorda tympani and have their cell bodies in the geniculate ganglion. Furthermore, the reduction in the number of Scarpa's ganglion cells observed in the dysautonomic patients studied here could account for a poor response to caloric test, positional vertigo and an unsteady gait in this condition.

Adolescent↗

PubMed2001

Experimental study on facial nerve regeneration with or without geniculate ganglionectomy.

OBJECTIVE: To investigate regeneration of the distal facial nerve following nerve grafting within the tympanic segment with geniculate ganglion preservation or dissection. DESIGN: Randomized controlled trial. SUBJECTS: Twenty-three adult New Zealand albino rabbits were used in this study. INTERVENTIONS: A 2-mm tympanic segment of the facial nerve was removed, and the greater auricular nerve was harvested for grafting in all animals. In group 1 (10 rabbits), the geniculate ganglion was preserved. In group 2 (13 rabbits), the geniculate ganglion was dissected. Mastoidal and extratemporal segments of the facial nerve were harvested 3 months postoperatively for histological examination by electron microscopy. RESULTS: The number of myelinated axons in normal facial nerves was 1819.6 +/- 535.6. In group 1, the number of myelinated axons was 123.6 +/- 31.1, and, compared with normal facial nerves, the diameter of the regenerative axons was decreased and the sheath thickness in the regenerative fiber was diminished. In group 2, the number of myelinated axons was 515.1 +/- 103.1, while the myelin sheath thickness was proportionate to axon diameter. (Data are given as mean +/- SD.) CONCLUSION: Geniculate ganglionectomy may improve motor axon regeneration.

Animals↗

PubMed1989

[An experimental study of herpes simplex virus infection in the facial nerve].

In the experimental animals, the author succeeded in establishing the pathogenicity of herpes simplex virus (HSV) in the facial nerve. KOS strain of HSV type 1 was inoculated to the tongue or the auricle of the balb/c mouse previously treated by intraperitoneal injection of cyclophosphamide. Between 4 and 12 days after the inoculation, the facial nerves were resected and submitted to histopathological and immunohistochemical investigations. Inflammatory changes were mainly observed in the geniculate ganglion and its proximal portion of the facial nerve irrespective of the site of the inoculation. In the same sites, HSV antigens were proved. The viral geniculate ganglionitis was induced in 21.4% of the animals inoculated to the tongue, 30.0% of those to the unilateral auricle, and 37.5% of those to the bilateral auricles respectively. This experiment demonstrated that HSV inoculated in the site innervated by sensory component of the facial nerve could affect the geniculate ganglion and its neighboring portion. These results presented a substantial support of the viral hypothesis in the etiology of Bell's palsy.

Animals↗

PubMed1991

MRI of the facial nerve during paralysis.

Gadolinium-enhanced MRI was used to evaluate 10 patients with Bell's palsy and one patient with facial paralysis secondary to Lyme disease. Nine of the eleven patients showed increased signal intensity of their facial nerve with gadolinium-enhanced MRI. In all nine patients, the facial nerve was involved at the labyrinthine, geniculate ganglion and proximal tympanic portions of the facial nerve, while two of the nine patients also had involvement of the mastoid segment of the facial nerve. Patients whose facial nerve enhancement was limited to the labyrinthine, geniculate ganglion and proximal tympanic facial nerve ultimately had complete return of facial function. Patients whose facial nerve enhanced in the mastoid segment experienced incomplete return of facial function. Gadolinium is effective in localizing the site of inflammation during facial paralysis. Those patients with enhancement localized to the labyrinthine, geniculate ganglion and proximal tympanic segments were more likely to regain complete facial function. In contrast, patients who had enhancement of the mastoid segment of the facial nerve had poorer prognoses for complete return of facial function.

Adolescent↗

PubMed1994

Idiopathic, herpetic, and HIV-associated facial nerve palsies: abnormal MR enhancement patterns.

PURPOSE: To determine specific criteria that can be used to define normal versus abnormal MR contrast enhancement of the facial nerve. METHODS: Twenty-three patients with acute unilateral inflammatory peripheral facial nerve palsy were examined on a 1.5-T MR using multiplanar T1-weighted spin-echo sequences before and after injection of gadopentetate dimeglumine. These MR patterns were compared with those of healthy control subjects. RESULTS: The normal facial nerve usually showed a mild to moderate enhancement of the geniculate ganglion and the tympanic-mastoid segment. The intracanalicular-labyrinthine segment did not enhance. All patients showed abnormal enhancement of the distal intracanalicular and the labyrinthine segment. An intense enhancement could be observed in the geniculate ganglion and the proximal tympanic segment, especially in herpetic palsy. Associated enhancement of the vestibulocochlear nerve was seen in herpetic and idiopathic palsy. Enhancement of the inner ear structures was detected only in herpetic palsy. CONCLUSIONS: Abnormal contrast enhancement of the distal intracanalicular and the labyrinthine facial nerve segment is observed in all patients and is the only diagnostically reliable MR feature proving an inflammatory facial nerve lesion. The intense enhancement of the geniculate ganglion and the proximal tympanic segment is possibly correlated with the reactivation of the latent infection in the sensory ganglion. The abnormal enhancement results from breakdown of the blood-peripheral nerve barrier and/or from venous congestion in the venous plexuses of the epi- and perineurium.

Acquired Immunodeficiency Syndrome↗

PubMed2000

Hemangioma of the facial nerve.

UNLABELLED: To discuss the interest of the etiologic diagnosis of a facial palsy. STUDY DESIGN AND PATIENTS: Two cases of geniculate ganglion hemangioma with progressive facial palsy are reported. RESULTS: Hemangioma of the facial nerve is a rare and benign vascular tumor that originates from the venous plexus surrounding the facial nerve. The most common locations are the internal auditory canal and the geniculate ganglion. Diagnosis of these small tumors is radiological with CT-scan and MRI studies. Surgical excision through a supra-petrosal approach is the gold standard treatment. Hemangiomas of the facial nerve and particularly those developed in the geniculate ganglion area constitute a rare but not inconsiderable facial palsy etiology. An acute diagnosis and an early excision are fundamental to preserve a satisfactory facial function.

Cranial Nerve Neoplasms↗

PubMedDate not supplied

Viral culture and electron microscopy of ganglion cells in Meniere's disease and Bell's palsy.

Specimens of Scarpa's ganglion during vestibular neurectomy were obtained in 6 cases of Meniere's disease and specimens of geniculate ganglion in 2 cases of total facial nerve decompression and studied by tissue culture methods for detection of possible herpes and cytomegalovirus infection. In electron microscopy inclusions in the form of interwoven yarn-like structures, coarse aggregates of chromatin and light nuclear bodies were found in several vestibular ganglion cells. No typical herpes virus virions could be demonstrated. The culture for viruses all proved finally negative. At present there is no proof that viruses are present in Scarpa's or geniculate ganglions but the possibility remains that the inclusion bodies observed might be viruses inactivated inside the ganglion cells.

Cell Nucleus↗

PubMed2004

Varicella zoster virus: beyond facial paralysis.

J. Ramsay Hunt's hypothesis that herpes zoster oticus results from a reactivation of the herpes zoster virus in the geniculate ganglion, has been supported by the demonstration of varicella zoster viral DNA in the geniculate ganglion of the side with facial paralysis in patients with Ramsay Hunt syndrome, with the use of the polymerase chain reaction. Similarly, DNA of the varicella zoster virus has been identified in the spiral and vestibular ganglion as well. We report on three patients with cochleovestibular symptoms as the first manifestations of Ramsay Hunt syndrome. A 64-year old woman and a 72-year old man presented with vertigo and an auricular herpetiform eruption. Only the woman developed later on a mild facial paralysis. A 58-year old man presented with an acute cochleovestibular syndrome, serologically proven to be a varicella zoster viral reactivation, which was followed three weeks later by the typical cutaneous recrudescence. We believe that these cases result from reactivation of latent varicella zoster virus in the spiral and/or vestibular ganglion. As the varicella zoster virus is dormant in the non-neuronal satellite cells, the facial symptoms in our patients as well as the high incidence of cochleovestibular symptoms in classical Ramsay Hunt syndrome can be explained by viral transmission across the nerves inside the internal auditory canal. Therefore, we think there are grounds to recommend a prompt treatment with an antiviral and a corticosteroid agent, not only in case of an acute facial paralysis but also when confronted with an acute cochleovestibular syndrome.

Acyclovir↗

PubMed2001

Epithelial overexpression of BDNF or NT4 disrupts targeting of taste neurons that innervate the anterior tongue.

Brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT4) are essential for the survival of geniculate ganglion neurons, which provide the sensory afferents for taste buds of the anterior tongue and palate. To determine how these target-derived growth factors regulate gustatory development, the taste system was examined in transgenic mice that overexpress BDNF (BDNF-OE) or NT4 (NT4-OE) in basal epithelial cells of the tongue. Overexpression of BDNF or NT4 caused a 93 and 140% increase, respectively, in the number of geniculate ganglion neurons. Surprisingly, both transgenic lines had severe reduction in fungiform papillae and taste bud number, primarily in the dorsal midregion and ventral tip of the tongue. No alterations were observed in taste buds of circumvallate or incisal papillae. Fungiform papillae were initially present on tongues of newborn BDNF-OE animals, but many were small, poorly innervated, and lost postnatally. To explain the loss of nerve innervation to fungiform papillae, the facial nerve of developing animals was labeled with the lipophilic tracer DiI. In contrast to control mice, in which taste neurons innervated only fungiform papillae, taste neurons in BDNF-OE and NT4-OE mice innervated few fungiform papillae. Instead, some fibers approached but did not penetrate the epithelium and aberrant innervation to filiform papillae was observed. In addition, some papillae that formed in transgenic mice had two taste buds (instead of one) and were frequently arranged in clusters of two or three papillae. These results indicate that target-derived BDNF and NT4 are not only survival factors for geniculate ganglion neurons, but also have important roles in regulating the development and spatial patterning of fungiform papilla and targeting of taste neurons to these sensory structures.

Animals↗