Effects of pharyngeal lubrication on the opening of obstructed upper airway

We examined the effect of electrical stimulation of the hypoglossal nerve and pharyngeal lubrication with artificial surfactant (Surfactant T-A) on the opening of obstructed upper airway in nine anesthetized supine dogs. The upper airway was isolated from the lower airway by transecting the cervical trachea. Upper airway obstruction was induced by applying constant negative pressures (5, 10, 20, and 30 cmH2O) on the rostral cut end of the trachea. Peripheral cut ends of the hypoglossal nerves were electrically stimulated by square-wave pulses at various frequencies from 10 to 30 Hz (0.2-ms duration, 5-7 V), and the critical stimulating frequency necessary for opening the obstructed upper airway was measured at each driving pressure before and after pharyngeal lubrication with artificial surfactant. The critical stimulation frequency for upper airway opening significantly increased as upper airway pressure became more negative and significantly decreased with lubrication of the upper airway. These findings suggest that greater muscle tone of the genioglossus is needed to open the occluded upper airway with larger negative intraluminal pressure and that lubrication of the pharyngeal mucosa with artificial surfactant facilitates reopening of the upper airway.

Branchial cleft cyst manifesting as hypoglossal nerve palsy

Hypoglossal nerve palsy occurred in 2 patients with infected second branchial arch cleft cyst. This very unusual complication of the congenital anomaly has been related to the mechanical compression of the mass. Histologic features of the perineural coat were also suggestive for this etio-pathogenesis.

A functional evaluation of ansa cervicalis nerve transfer for unilateral vocal cord paralysis: future directions for laryngeal reinnervation

There are a variety of methods for treating unilateral vocal cord paralysis, but to date there are few objective studies that evaluate the functional results of nerve transfer from the ansa cervicalis. Six dogs underwent unilateral recurrent laryngeal nerve section with immediate reanastamosis to the sternothyroid branch of the ansa cervicalis. After 5 to 6 months, measurements of vocal efficiency and acoustic parameters, videolaryngoscopy, videostroboscopy, and evoked electromyography were performed. Identical measurements were made in eight control dogs during normal electrically induced phonation and a simulated unilateral recurrent laryngeal nerve paralysis. Histologic analysis of both vocalis muscles, recurrent laryngeal nerves, ansa cervicalis, and the ansa-recurrent laryngeal nerve anastamosis site was performed. Evidence of reinnervation was found in all of the animals that underwent nerve transfer. The vocal efficiency and acoustic quality after ansa cervicalis nerve transfer were dependent on the degree of electrical stimulation from the transferred nerve to the reinnervated cord during phonation. In the absence of electrical stimulation to the nerve transfer, physiologic vocal cord motion could not be elicited from the reinnervated cord.

Isolated hypoglossal nerve palsy and Horner's syndrome with benign course

Images

Posterior fossa arachnoid cyst presenting with an isolated twelfth nerve paresis. Case report and review of the literature

An unusual case of a posterior fossa arachnoid cyst containing atypical fluid is described in a patient presenting with an isolated ipsilateral twelfth nerve paresis. Despite the chronicity of symptoms, surgical decompression resulted in a satisfactory functional recovery.

Unitary correlates of linguo-pharyngeal events in a dyskinetic rat model

1. The hypoglossal nucleus unitary correlates of ketamine- and electrically induced tongue contractions and swallowing events were recorded and compared in stereotaxically mounted rats. 2. Very few of the units recorded could be identified as motoneurons by antidromic invasion through electrical stimulation of the hypoglossal nerve. 3. The sample consists of 109 units, 2/3 of which were located in the retrusor pool and 1/3 in the protrusor region. 4. Linguo-pharyngeal events were considered to be electrically induced if they followed consistently, and with a relatively fixed latency, a single electrical pulse delivered to the superior laryngeal nerve, and ketamine-induced if no such time-locked sequence existed or if they occurred in the absence of electrical stimulation. 5. No differences could be discovered between the two types of linguo-pharyngeal events whether they were compared at the polygraphic or the unitary level. 6. These findings suggest that pharmacologically (ketamine)-induced dyskinetic activity does not differ from comparable motor patterns induced by classical electrophysiological means.

Surgical reneurotization of the tongue after unilateral paralysis of the hypoglossal nerve

Hemiglossal paralysis due to lesions of the peripheral hypoglossal nerve leads to marked muscle atrophy with disturbed functioning in a minority of cases. Reinnervation from the unparalyzed, contralateral side may then be desired. In animal experiments on cats, a Z-plasty of the midportion of the tongue was carried out by transposing a portion of the normal tongue musculature into the opposite side following denervation 1 month previously by resection of the hypoglossal nerve. Electromyography was performed 13 months later. The tongue was then examined histochemically in serial sections in search of the motor endplates together with the nerves fibers. However, there was no evidence for reinnervation in the specimens examined. Signs of successful "reanimation" of the tongue by Z-plasty may be caused by mechanical synkinesia due to scar formation rather than by actual reneurotization.

Response properties of nociceptive and non-nociceptive neurons in the rat's trigeminal subnucleus caudalis (medullary dorsal horn) related to cutaneous and deep craniofacial afferent stimulation and modulation by diffuse noxious inhibitory controls

An electrophysiological study was carried out in anesthetized rats to characterize the properties of single neurons in trigeminal (V) subnucleus caudalis. Each neuron was functionally classified in terms of its cutaneous mechanoreceptive field properties as low-threshold mechanoreceptive (LTM), wide dynamic range (WDR) or nociceptive-specific (NS), and its responsiveness was also tested to electrical stimulation of hypoglossal (XII) nerve muscle afferents. Some neurons were also tested with noxious stimulation of the tail or forepaw for the presence of diffuse noxious inhibitory controls (DNIC) of evoked responses. A mechanoreceptive field localized to the ipsilateral orofacial region was a feature of all the neurons which were located in laminae I-VI; the LTM neurons predominated in laminae III/IV whereas the nociceptive (WDR, NS) were located in the superficial and especially deeper laminae of caudalis. The majority of the WDR and NS neurons were also activated by noxious heating as well as by noxious mechanical and electrical stimulation of their orofacial mechanoreceptive field, and in contrast to our previous studies in cats, most of these caudalis nociceptive neurons received C fiber as well as A fiber cutaneous afferent inputs. In contrast to the LTM neurons, but consistent with our previous data in cats, many of the nociceptive neurons also received convergent excitatory inputs from XII muscle afferents, and the stimulus-response functions of the WDR neurons indicated that they were capable of coding the intensity of A and C fiber craniofacial muscle afferent inputs as well as those from cutaneous afferents. The study has also documented for the first time that muscle afferent-evoked responses as well as those evoked by cutaneous afferent inputs to nociceptive neurons are subject to DNIC. These findings indicate that subnucleus caudalis plays an important role in the transmission of superficial and deep nociceptive information from the craniofacial region of the rat, and also reveal that responses of the nociceptive neurons evoked by deep as well as superficial afferent inputs can be powerfully modulated by other nociceptive influences originating from widespread parts of the body.

Activity of respiratory-related oropharyngeal and laryngeal motoneurones during fictive vomiting in the decerebrate cat

Activities of respiratory laryngeal and oropharyngeal respiratory nerves were studied during fictive vomiting elicited by supradiaphragmatic vagus nerve stimulation in the decerebrate cat. Inspiratory laryngeal nerves were strongly inhibited throughout the retching and expulsion phase. Glossopharyngeal, hypoglossal and expiratory laryngeal nerves were coactivated with the phrenic and abdominal nerve bursts. The pharyngeal branch of the vagus nerve discharged during the phrenic and abdominal inter-burst of the retching phase, and was silent during the abdominal expulsion. These activities permit speculation about the role of upper airway muscles during vomiting.

Intracranial nonspecific inflammatory granuloma

A case of nonspecific inflammatory granuloma arising from the dura mater near the hypoglossal canal is reported. A 38-year-old woman developed an isolated left hypoglossal nerve palsy. Computed tomography and magnetic resonance imaging demonstrated an enhanced tumorous lesion at the inner orifice of the left hypoglossal canal. Skull x-ray was normal, and cerebral angiography showed no vascular abnormalities. Examination of the cerebrospinal fluid showed mild pleocytosis with a predominance of lymphocytes. Systemic examination revealed no abnormalities. The tumor was removed completely and pathologic investigation revealed that it was an inflammatory granuloma. The patient's history and laboratory data, however, failed to suggest the underlying disease, and histopathologic examination did not indicate any special type of granuloma. Therefore, the lesion was diagnosed as a nonspecific inflammatory granuloma.

Bilateral hypoglossal palsies: a late complication of curative radiotherapy

A 57 year old man developed bilateral hypoglossal nerve palsies 6 years after radiotherapy for carcinoma of the uvula. Follow-up over 2 years has demonstrated no evidence of tumour recurrence and no sign of neurological improvement. Reactive fibrosis and vascular insufficiency secondary to radiation and may have lead to hypoglossal nerve compression and infarction.

Brachial plexus injury and hypoglossal paralysis

Two neonates born after traumatic deliveries presented with injuries of the upper brachial plexus and ipsilateral hypoglossal nerve. In addition, 1 patient presented with paresis of the diaphragm after breech delivery; the other patient presented with signs of recurrent laryngeal nerve involvement after vertex delivery. Both infants recovered spontaneously.

[Assessment of motor cranial nerve functions using transcranial magnetic stimulation]

Transcranial magnetic stimulation applied over one cerebral hemisphere evokes bilateral responses in the muscles supplied by cranial nerves (masseter, mentalis, sternomastoid, genioglossus) (Tabl. 1). The relatively long latencies of these responses and the influence that preactivation of the muscle has on them, suggests that they are cortically evoked. Shorter latency and exclusively ipsilateral responses can be obtained if the position of the stimulating coil over the head is more lateral. These responses are uninfluenced by pre-activation of the muscle which suggests that they arise from stimulation of the peripheral nerve itself. By considering the conduction velocity of the nerve and the response latency such stimulation probably occurs in the proximal intracisternal segment (Fig. 2). The results obtained using magnetic stimulation of the cortex in patients with unilateral cerebral hemisphere lesions lend support to the idea of a bilateral projection from each cerebral hemisphere to the motor nuclei of the facial and hypoglossal nerves on both sides: stimulations over the intact hemisphere produces bilateral responses, whereas stimulations over the damaged hemisphere produce no responses (Fig. 1). In patients with idiopathic facial palsy no short latency responses were obtained on the affected side either during the acute (less than 10 days) or during the chronic phase (greater than 3 months) of the illness-despite clinical improvement during the chronic stage (Fig. 3, 4). However cortically evoked responses were obtainable in patients seen during the chronic phase indicating that facial motoneurones could be excited transsynaptically (Fig. 3).(ABSTRACT TRUNCATED AT 250 WORDS)

Hypoglossal nerve palsy after tooth extraction

A rare complication involving hypoglossal nerve paralysis after extraction of third molars is reported. The possible pathophysiology of the condition is discussed. The paralysis was temporary and resolved within one week of surgery.

Influence of extreme hypercapnia on respiratory motor nerve activity in cats

Sedative drugs have been found to depress the respiratory activity of upper airway muscles more than that of the diaphragm. To determine whether CO2 at narcotic levels has a similar action, we recorded phrenic and hypoglossal nerve activities in decerebrate, vagotomized, paralyzed cats. T5 or T6 external intercostal nerve activity was also recorded in some animals. End-tidal CO2 concentration was raised progressively to over 30% or until depression of nerve activity was apparent. Respiratory frequency was reduced by severe hypercapnia in most cats. Hypoglossal nerve activity was consistently decreased more than that of the phrenic nerve. In most cases intercostal nerve activity was also more susceptible than phrenic nerve activity to hypercapnic depression. The results indicate that CO2 at narcotic levels interferes both with the central pattern generator for breathing movements and with the expression of the pattern in specific motor nerves.

Comparison of the effects of hypercapnia on phrenic and hypoglossal activity in anesthetized decerebrate and decorticate animals

To examine the effects of suprapontine structures on the activity of hypoglossal and phrenic nerves, 13 chloralose anesthetized, paralyzed (gallamine triethiodide) and artificially ventilated cats were studied. In all animals vagi and carotid sinus nerves were cut bilaterally. All animals were first hyperventilated to apnea and then made progressively hypercapnic by rebreathing under hyperoxic conditions. Following midcollicular decerebration, the peak phasic activity of the hypoglossal nerve was significantly depressed and the PCO2 at which apnea occurred (apneic point) increased. However, following high decerebration or decortication the activity of the hypoglossal nerve was increased at higher CO2 levels and there was no change in apneic point. By contrast, peak phrenic nerve activity was not altered by any of the above surgical procedures. Neither systemic blood pressure nor respiratory frequency were significantly altered by these procedures. The results indicate that suprapontine structures can appreciably modify hypoglossal activity.

Preliminary observations after facial rehabilitation with the ansa hypoglossi pedicle transfer

Facial paralysis is a very disabling condition, both functionally and cosmetically. Despite the different methods of facial reanimation that have been described, there is no single method that will restore normal facial tone and motion. Of the methods available, primary neurorrhaphy is probably the most effective. The recovery period, however, is prolonged and, as a result, muscle tone and bulk may be lost. The hypoglossal-facial anastomosis is also a very reliable and effective technique but requires necessary interruption of both major cranial nerve trunks. Transfer of a neuromuscular pedicle (based on the ansa hypoglossi) has been offered as a method of facial reanimation that involves neither prolonged recovery nor interruption of the major cranial nerve functions. The application of this technique for reinnervation of a paralyzed larynx was first described by Tucker in 1970, and the technique was applied to facial muscle (in animal models) in 1977. The effectiveness of this technique--and its application in the management of facial paralysis in the human patient--remains controversial. We report our experience with a series of six patients who underwent neuromuscular pedicle transfer in conjunction with other more conventional methods of facial reanimation. The function of the pedicle and its contribution to the overall facial rehabilitation were assessed clinically and electromyographically. Factors influencing the success of the procedure and clinical and experimental evidence to support its application are discussed. While our experience with this technique is limited, it would appear that the neuromuscular pedicle transfer may play a useful adjunctive role in reanimation of the face in selective cases of facial paralysis.

Distinguishing between extrinsic and intrinsic tongue muscle weakness in unilateral hypoglossal palsy

A 53-year-old man presented with multiple right cranial nerve palsies that included the tongue. When the tongue was protruded, it deviated to the right. However, when the tongue was not protruded, he could readily turn the tip of the tongue to the left, but not to the right. Protrusion of the tongue requires the action of extrinsic tongue muscles, but lateral movements of the nonprotruded tongue are accomplished by intrinsic tongue muscles.

Cortically induced postsynaptic potentials in hypoglossal motoneurons after axotomy

Cortically induced postsynaptic potentials were studied in normal and axotomized cat hypoglossal motoneurons. In normal protruder motoneurons innervating tongue protruder muscles, we have demonstrated that stimulation of the orbital gyrus, at the point optimum for inducing lapping movements of the tongue by repetitive stimuli, produced inhibitory postsynaptic potentials or excitatory postsynaptic potentials followed by predominant inhibitory postsynaptic potentials. The cortically induced excitatory postsynaptic potential in normal protruder motoneurons was composed of only the short-latency component. In protruder motoneurons 30, 40, 60 and 80 days after axotomy, we have demonstrated that the number of protruder motoneurons responding with two components of excitatory postsynaptic potentials (the short- and the long-latency component) to cortical stimulation increased in correspondence with the lapse of days after axotomy and that the amplitude of cortically induced inhibitory postsynaptic potentials in axotomized protruder motoneurons was reduced in size as compared with normal protruder motoneurons.

Lower cranial nerve motor function in unilateral vascular lesions of the cerebral hemisphere

Motor function subserved by cranial nerves V, VII, X, XI, and XII was assessed in 100 patients with hemiparesis due to a unilateral vascular lesion of the cerebral hemisphere. Several of the findings were not described clearly in many of the standard textbooks of neurology. Weakness of sternomastoid when present was always contralateral to the hemiparesis. This emphasises the principle that the cerebral hemisphere controls movement of the body parts in or towards the contralateral half of the body rather than simply the contralateral muscle groups. An apparent exception to this was seen, however, in the small group of patients who had unilateral weakness of the tongue. In those patients deviation of the tongue was towards the hemiparetic side--that is, the cerebral hemisphere controlled the contralateral half of the tongue and hence protrusion towards the ipsilateral side. Mild dysarthria was common with both right and left sided hemiparesis.