Glossopharyngeal neuralgia secondary to vascular compression in a patient with multiple sclerosis: a case report

ABSTRACT: Glossopharyngeal neuralgia is an uncommon, painful syndrome, characterized by paroxysmsof pain in the sensory distribution of the 9th cranial nerve. Idiopathic glossopharyngealneuralgia may be due to compression of the glossopharyngeal nerve by adjacent vessels,while secondary glossopharyngeal neuralgia is associated with identifiable lesions affectingthe glossopharyngeal nerve at different levels of its neuroanatomic pathway.Glossopharyngeal neuralgia is rare in the general population, but is more common in patientswith multiple sclerosis. CASE PRESENTATION: A 56-year-old Caucasian woman with multiple sclerosis and migraine presented to ourfacility with intermittent lancinating pain to the right of her throat, tongue, and the floor ofher mouth that had been occurring for the past year. The pain was intense, sharp, andstabbing, which lasted two to six seconds with radiation to the right ear. Initially, the attackswere infrequent, however, they had become more intense and frequent over time. Our patientreported weight loss, headache, painful swallowing, and the inability to maintain sleep due topainful attacks. A neurological examination revealed a right-handed woman with triggerpoints in the back of the tongue and throat on the right side. She also had dysphagia,hoarseness, and pain in the distribution of the right glossopharyngeal nerve. Mild righthemiparesis, hyperreflexia, dysmetria, and an ataxic gait were present. A magnetic resonanceimaging scan of the brain was consistent with multiple sclerosis and magnetic resonanceangiography demonstrated a loop of the posterior inferior cerebellar artery compressing theright glossopharyngeal nerve. She responded satisfactorily to carbamazepine. Microvasculardecompression and Gamma Knife? radiosurgery were discussed in case of failure of themedical treatment; however, she declined these options. CONCLUSIONS: Glossopharyngeal neuralgia in multiple sclerosis may occur due to vascular compressivelesions and it should not be solely attributed to the underlying demyelinating process.Vascular compression of the glossopharyngeal nerve could independently causeglossopharyngeal neuralgia in patients with multiple sclerosis, and vascular imaging toexclude such a diagnosis is recommended.     

Histoarchitectonics of the cholinergic innervation of the frog tongue

Acetylcholinesterase (AChE) activity was studied in dorsal tongue surface structures and in both tongue nerves (hypoglossal and glossopharyngeal) of frogs (Rana temporaria). AChE was found in nerve fibers of fungiform and filiform papillae, blood vessels, glandular ducts of tongue mucosa, both nerve fibers and also in the bodies of cholinergic neurons in subepithelial connective tissue and along the glossopharyngeal nerve. Their parasympathetic origin was suggested. The experiments with butirilthiocholin have revealed no activity of non-specific cholinesterases in the above structures. Possible role of cholinergic system in the regulation of tongue receptor function is discussed.     

Taste-responsive neurons in the nucleus of the solitary tract receive gustatory information from both sides of the tongue in the hamster

Taste receptors on the left and right sides of the anterior tongue are innervated by chorda tympani (CT) fibers, which carry taste information to the ipsilateral nucleus of the solitary tract (NST). Although the anterior tongue is essential for taste, patients with unilateral CT nerve damage often report no subjective change in their taste experience. The standing theory that explains the taste constancy is the "release of inhibition", which hypothesizes that within the NST there are inhibitory interactions between inputs from the CT and glossopharyngeal nerves and that the loss of taste information from the CT is compensated by a release of inhibition on the glossopharyngeal nerve input. However, the possibility of compensation by taste input from the other side of the tongue has never been investigated in rodents. We recorded from 95 taste-responsive neurons in the NST and examined their responsiveness to stimulation of the contralateral CT. Forty-six cells were activated, mostly with excitatory responses (42 cells). Activation of NST cells induced by contralateral CT stimulation was blocked by microinjection of lidocaine into the contralateral NST but was not affected by anesthetization of the contralateral parabrachial nuclei (PbN). In addition, the NST cells that were activated by contralateral CT stimulation showed reduced responsiveness to taste stimulation after microinjection of lidocaine into the contralateral NST. These results demonstrate that nearly half of the taste neurons in the NST receive gustatory information from both sides of the tongue. This "cross talk" between bilateral NST may also contribute to the "taste constancy".     

Percutaneous radiofrequency glossopharyngeal rhizotomy for cancer pain

15 patients with pain secondary to cancer underwent radiofrequency glossopharyngeal rhizotomy by the percutaneous approach. 11 patients had complete relief while 4 patients had partial relief. All patients presented, after surgery, some impairment in glossopharyngeal function.     

Five-and-a-half years' experience with percutaneous retrogasserian glycerol rhizotomy in treatment of trigeminal neuralgia

The results of treating trigeminal neuralgia with percutaneous retroganglionic glycerol rhizotomy in 319 patients from an overall series of 394 patients with 459 operations carried out over a period of 5 1/2 years are reported. Idiopathic trigeminal neuralgia was the diagnosis in 252 patients. 34 patients had trigeminal neuralgia associated with multiple sclerosis. The remaining 33 patients suffered from symptomatic trigeminal neuralgia or atypical facial pain. 230 patients (91.3%) with idiopathic trigeminal neuralgia and 30 patients (88.2%) with multiple sclerosis reported complete freedom from pain. In 12 patients (4.8%) of those with tic douloureux and in 1 patient (2.9%) with multiple sclerosis, pain was alleviated, and the patients required a reduced pharmacotherapy. 10 patients (3.9%) and 3 patients (8.8%) were considered to be treatment failures. The rate of recurrences within the first 2 years was 10.9 and 40.0%, respectively. In the long-term, the rate of recurrences in patients with tic douloureux was 36.9%. 144 patients (45.1%) noticed a hypesthesia. 132 patients (41.4%) had hypalgesia following the procedure, and there was a decrease of symptoms in the long-term observation in 20.0% of the patients. 59 patients (18.5%) developed dysesthesia postoperatively which regressed only to an inappreciable extent in the long-term course. In 16 patients (5.0%) exclusively with a preexisting organic lesion or who had received surgical pretreatment, there was a loss of corneal sensation. The investigation showed on the one hand the effectiveness of the method, but on the other hand also the possibility of marked sensory disorder in selected cases.     

The origin of slow potentials on the tongue surface induced by frog glossopharyngeal efferent fiber stimulation

When the glossopharyngeal (GP) nerve of the frog was stimulated electrically, electropositive slow potentials were recorded from the tongue surface and depolarizing slow potentials from taste cells in the fungiform papillae. The amplitude of the slow potentials was stimulus strength- and the frequency-dependent. Generation of the slow potentials was not related to antidromic activity of myelinated afferent fibers in the GP nerve, but to orthodromic activity of autonomic post-ganglionic C fibers in the GP nerve. Intravenous injection of atropine abolished the positive and depolarizing slow potentials evoked by GP nerve stimulation, suggesting that the slow potentials were induced by the activity of parasympathetic post-ganglionic fibers. The amplitude and polarity of the slow potentials depended on the concentration of adapting NaCl solutions applied to the tongue surface. These results suggest that the slow potentials recorded from the tongue surface and taste cells are due to the liquid junction potential generated between saliva secreted from the lingual glands by GP nerve stimulation and the adapting solution on the tongue surface.     

Radiofrequency thermocoagulation of Gasserian ganglion and its rootlets for trigeminal neuralgia.

Thirty-nine patients with trigeminal neuralgia, not controlled by medical treatment, were treated by radio-frequency thermocoagulation of the Gasserian ganglion and its posterior rootlets. Thirty-six received satisfactory pain relief. In 30 patients touch sensation in the treated territory was preserved. The corneal reflex was affected in only six patients, two of whom subsequently developed keratitis. There were no other complications apart from a minor unpleasant sensation in eight patients. By selectively destroying pain fibres this technique offers the scope of preserving touch sensation in the treated area. Moreover, the zone of analgesia can be restricted to the affected region by sensory mapping through electrode stimulation before thermocoagulation. Its simplicity, low morbidity, associated short hospital stay, and the increased ability to preserve touch sensation, especially of the cornea, seem to make it preferable to other forms of surgical management for trigeminal neuralgia.     

Upper airway muscle paralysis reduces reflex upper airway motor response to negative transmural pressure in rat.

The reflex upper airway (UA) motor response to UA negative pressure (UANP) is attenuated by neuromuscular blockade. We hypothesized that this is due to a reduction in the sensitivity of laryngeal mechanoreceptors to changes in UA pressure. We examined the effect of neuromuscular blockade on hypoglossal motor responses to UANP and to asphyxia in 15 anesthetized, thoracotomized, artificially ventilated rats. The activity of laryngeal mechanoreceptors is influenced by contractions of laryngeal and tongue muscles, so we studied the effect of selective denervation of these muscle groups on the UA motor response to UANP and to asphyxia, recording from the pharyngeal branch of the glossopharyngeal nerve (n = 11). We also examined the effect of tongue and laryngeal muscle denervation on superior laryngeal nerve (SLN) afferent activity at different airway transmural pressures (n = 6). Neuromuscular blockade and denervation of laryngeal and tongue muscles significantly reduced baseline UA motor nerve activity (P < 0.05), caused a small but significant attenuation of the motor response to asphyxia, and markedly attenuated the response to UANP. Motor denervation of tongue and laryngeal muscles significantly decreased SLN afferent activity and altered the response to UANP. We conclude that skeletal muscle relaxation reduces the reflex UA motor response to UANP, and this may be due to a reduction in the excitability of UA motor systems as well as a decrease of the response of SLN afferents to UANP.     

Neuropathic orofacial pain: Cannabinoids as a therapeutic avenue

Neuropathic orofacial pain (NOP) exists in several forms including pathologies such as burning mouth syndrome (BMS), persistent idiopathic facial pain (PIFP), trigeminal neuralgia (TN) and postherpetic neuralgia (PHN). BMS and PIFP are classically diagnosed by excluding other facial pain syndromes. TN and PHN are most often diagnosed based on a typical history and presenting pain characteristics. The pathophysiology of some of these conditions is still unclear and hence treatment options tend to vary and include a wide variety of treatments including cognitive behaviour therapy, anti-depressants, anti-convulsants and opioids; however such treatments often have limited efficacy with a great amount of inter-patient variability and poorly tolerated side effects. Analgesia is one the principal therapeutic targets of the cannabinoid system and many studies have demonstrated the efficacy of cannabinoid compounds in the treatment of neuropathic pain. This review will investigate the potential use of cannabinoids in the treatment of symptoms associated with NOP.     

Taste transduction mechanism: similar effects of various modifications of gustatory receptors on neural responses to chemical and electrical stimulation in the frog

Responses in the frog glossopharyngeal nerve induced by electrical stimulation of the tongue were compared with those induced by chemical stimuli under various conditions. (a) Anodal stimulation induced much larger responses than cathodal stimulation, and anodal stimulation of the tongue adapted to 5 mM MgCl2 produced much larger responses than stimulation with the tongue adapted to 10 mM NaCl at equal current intensities, as chemical stimulation with MgCl2 produced much larger responses than stimulation with NaCl at equal concentration. (b) The enhansive and suppressive effects of 8-anilino-1-naphthalenesulfonate, NiCl2, and uranyl acetate on the responses to anodal current were similar to those on the responses to chemical stimulation. (c) Anodal stimulation of the tongue adapted to 50 mM CaCl2 resulted in a large response, whereas application of 1 M CaCl2 to the tongue adapted to 50 mM CaCl2 produced only a small response. This, together with theoretical considerations, suggested that the accumulation of salts on the tongue surface is not the cause of the generation of the response to anodal current. (d) Cathodal current suppressed the responses induced by 1 mM CaCl2, 0.3 M ethanol, and distilled water. (e) The addition of EGTA or Ca-channel blockers (CdCl2 and verapamil) to the perfusing solution of the lingual artery reversibly suppressed both the responses to chemical stimulus (NaCl) and to anodal current with 10 mM NaCl. (f) We assume from the results obtained that electrical current from the microvillus membrane of a taste cell to the synaptic area supplied by anodal stimulation or induced by chemical stimulation activates the voltage-dependent Ca channel at the synaptic area.     

Patterns of peripheral innervation of the tongue and hyobranchial apparatus in caecilians (Amphibia: Gymnophiona).

The innervation of the musculature of the tongue and the hyobranchial apparatus of caecilians has long been assumed to be simple and to exhibit little interspecific variation. A study of 14 genera representing all six families of caecilians demonstrates that general patterns of innervation by the trigeminal, facial, glossopharyngeal, and vagus nerves are similar across taxa but that the composition of the "hypoglossal" nerve is highly variable. Probably in all caecilians, spinal nerves 1 and 2 contribute to the hypoglossal. In addition, in certain taxa, an "occipital," the vagus, and/or spinal 3 appear to contribute fibers to the composition of the hypoglossal nerve. These patterns, the lengths of fusion of the contributing elements, and the branching patterns of the hypoglossal are assessed according to the currently accepted hypothesis of phylogenetic relationships of caecilians, and of amphibians. An hypothesis is proposed that limblessness and a simple tongue, with concomitant reduced complexity of innervation of muscles associated with limbs and the tongue, has released a constraint on pattern of innervation. As a consequence, a greater diversity and, in several taxa, greater complexity of neuroanatomical associations of nerve roots to form the hypoglossal are expressed.     

A Cost-Consequences analysis of the effect of Pregabalin in the treatment of peripheral Neuropathic Pain in routine medical practice in Primary Care settings

Background  

Neuropathic pain (NeP) is a common symptom of a group of a variety of conditions, including diabetic neuropathy, trigeminal neuralgia, or postherpetic neuralgia. Prevalence of NeP has been estimated to range between 5-7.5%, and produces up to 25% of pain clinics consultations. Due to its severity, chronic evolution, and associated co-morbidities, NeP has an important individual and social impact. The objective was to analyze the effect of pregabalin (PGB) on pain alleviation and longitudinal health and non-health resources utilization and derived costs in peripheral refractory NeP in routine medical practice in primary care settings (PCS) in Spain.     

Nutrient tasting and signaling mechanisms in the gut. IV. There is more to taste than meets the tongue

The tongue is the principal organ that provides sensory information about the quality and quantity of chemicals in food. Other information about the temperature and texture of food is also transduced on the tongue, via extragemmal receptors that form branches of the trigeminal, glossopharyngeal, and vagal nerves. These systems, together with information from the gastrointestinal (GI) system, interact to determine whether or not food is palatable. In this themes article, emphasis is placed on the integrative aspects of gustatory processing by showing the convergence of gustatory information with somatosensory, nociceptive, and visceral information (from the GI system) on the tongue and in the brain. Our thesis is that gustation should be thought of as an integral part of a distributed, interacting multimodal system in which information from other systems, including the GI system, can modulate the taste of food.     

Centrifugal decrement in diameter of myelinated afferent fibres innervating frog taste organ

1. Regional changes in the diameter of single myelinated afferent nerve fibres innervating the taste disc of the fungiform papillae on the bullfrog tongue were investigated morphologically and functionally. 2. The diameter of myelinated afferents in the medial lingual branch of the glossopharyngeal nerve averaged 8.4 microns at the proximal end of the tongue and gradually decreased at the rate of 0.8 micron/cm length of the fibres as they ran in the apical direction of the tongue. 3. The conduction velocity of single myelinated afferent fibres within the tongue decreased gradually as they ran peripherally. 4. Electrophysiological inspection of neural connections between the fungiform papillae suggests that a gradual centrifugal decrease in the diameter of a single myelinated afferent fibre is not due to multiple bifurcations of the fibre at various sites within the tongue, but due to a natural gradual decrease in the thickness of the myelin sheath and the diameter of axon.     

Percutaneous Radio-Frequency Rhizotomy in the Treatment of Trigeminal Neuralgia

A percutaneous technique of selective partial trigeminal root coagulation was evaluated in the treatment of 38 patients suffering from trigeminal neuralgia, 1 patient with pain secondary to oral carcinoma and 1 patient with atypical facial pain. The pain of trigeminal neuralgia was relieved in 94.7 percent of patients. Pain was relieved in the patient with oral carcinoma, but not in the patient with atypical facial pain. There was no mortality and no permanent morbidity outside of the trigeminal nerve lesion. The procedure requires only a brief hospital stay without the time, expense and hazards of open cranial surgical procedures.     

Labeling afferent nerves in the tongue by peripheral transganglionic transport of HRP and WGA-HRP in the rat

Peripheral transganglionic transport of horseradish pcroxidase(HRP) and wheat germ agglutinin–horseradish peroxidaseconjugate (WGA–HRP) was used to label afferent fibersin the taste buds and lingual epithelium of the rat. Microinjectionsof the tracer were made in the brain stem central projectionarea of the afferent nerves to the tongue. Optimal labelingof nerve endings in the tongue was obtained when 2 µlof 20% HRP was injected into the brain stem and postinjectionsurvival times of 24–36 h were used. The distributionof single nerves was studied by using this tracing procedurein combination with strategic transections of the various afferentnerves supplying the tongue. Labeled nerve fibers from the combinedchorda tympani–lingual nerve were found in the epitheliumand in taste buds in the fungiform and anterior foliate papillaeof the anterior 3/4 of the tongue. Labeled nerve fibers in theepithelium of the anterior 2/3 of the tongue but none in tastebuds were found when the lingual nerve alone was studied, althoughnumerous perigeminal fibers were found. The glossopharyngealnerve was found to innervate die posterior 1/4 of the tongueepithelium including the taste buds of the circumvallate papillae.The glossopharyngeal nerve on one side was found to innervatethe taste buds on both sides of the midline. The results showthat this tracing procedure can be a useful supplement to othermethods for studying afferent nerves in the tongue.     

Taste responses to amino acids in the southern leopard frog, Rana sphenocephala

Integrated taste recordings of the glossopharyngeal (IX) nerve innervating the tongue of the southern leopard frog were studied in response to various amino acids and quinine hydrochloride. Amino acids and quinine hydrochloride elicited primarily phasic taste responses. Acidic (L-aspartic and L-glutamic) and basic (L-lysine and L-arginine) amino acids, adjusted to pH8, were effective taste stimuli. All glossopharyngeal nerve twigs that responded to amino acid stimuli also responded to quinine; however, not all quinine-sensitive IX nerve bundles were responsive to amino acids. Electrophysiological thresholds for amino acids were estimated to be 2.5-10 mM, whereas threshold for quinine hydrochloride averaged approximately 10 microM.     

Physicochemical studies of taste reception. V. Suppressive effect of salts on sugar response of the frog

The model membrane composed of a Millipore filter paper and the total lipids from bovine tongue epithelium or phosphatidylcholine from egg yolk simulated well the water response of a living taste cell. The water response observed with the model membrane adapted to various salt solutions was interpreted in terms of changes in electric potential at the membrane-solution interface, i.e. the water response was attributed to the e.m.f. change produced by diffusion of the electrolytes dissolved in (or adsorbed on) the membrane surface into the bulk solution.The water response of the frog tongue was also investigated by measuring the neural response of the glossopharyngeal nerve. The results obtained were consistent with the mechanism proposed in the present paper. The response of the frog to Ca²⁺ was examined under the condition where the water response was suppressed, and it was concluded that the water response of the frog is different from the response to Ca²⁺.     

Physicochemical studies of taste reception. III. Interpretation of the water response in taste reception

The model membrane composed of a Millipore filter paper and the total lipids from bovine tongue epithelium or phosphatidylcholine from egg yolk simulated well the water response of a living taste cell. The water response observed with the model membrane adapted to various salt solutions was interpreted in terms of changes in electric potential at the membrane-solution interface, i.e. the water response was attributed to the e.m.f. change produced by diffusion of the electrolytes dissolved in (or adsorbed on) the membrane surface into the bulk solution.The water response of the frog tongue was also investigated by measuring the neural response of the glossopharyngeal nerve. The results obtained were consistent with the mechanism proposed in the present paper. The response of the frog to Ca²⁺ was examined under the condition where the water response was suppressed, and it was concluded that the water response of the frog is different from the response to Ca²⁺.     

Non-synaptic transformation of gustatory receptor potential by stimulation of the parasympathetic fiber of the frog glossopharyngeal nerve

When the glossopharyngeal nerve (GP) in the frog was strongly stimulated electrically, slow potentials were elicited from the tongue surface and taste cells in the fungiform papillae. Injection of atropine completely blocked these slow potentials. The present and previous data indicate that the slow potentials induced in the tongue surface and taste cells are due to a liquid junction potential between saliva secreted from the lingual glands due to parasympathetic fiber activity and an adapting solution on the tongue surface. Intracellularly recorded depolarizing receptor potentials in taste cells induced by 0.5 M NaCl and 3 mM acetic acid were enhanced by depolarizing slow potentials induced by GP nerve stimulation, but were depressed by the hyperpolarizing slow potentials. On average, the receptor potential of taste cells for 0.5 M NaCl was increased by 25% by the GP nerve-induced slow potential, but the receptor potential of taste cells for 3 mM acetic acid was decreased by 1% by the slow potential. These transformations of receptor potentials in frog taste cells were not due to a synaptic event initiated between taste cells and the efferent nerve fiber, but due to a non-synaptic event, a lingual junction potential generated in the dorsal lingual epithelium by GP nerve stimulation.