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Voluntary dental students received 1 injection of 1,8 ml 3% Prilocain-fenylpressin. The injection was directed beneath the mylohyoid muscle immediately behind the distal root of the first molar in order to achieve anesthesia of the mylohyoid nerve. A partial anesthesia was achieved in 21% of the subjects. In those cases, the mylohyoid nerve is, in addition to its motor innervation, also sensory to first mandibular molar.
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Several complications following a mandibular nerve block were reported in the literature. In some cases pterygomandibular abscess formation may be caused by mandibular needle injections. There is no report of odontogenic osteomyelitis of the ascending mandibular ramus in the literature. Here two patients with osteomyelitis of the ascending ramus following a mandibular nerve block injection are presented.
PURPOSE: This study was designed to determine the incidence of altered sensation in patients undergoing mandibular endosseous implant placement. PATIENTS AND METHODS: Ninety-four consecutive patients who underwent the placement of mandibular implants constituted the study group. The only patients that were excluded from this study were those who had preexisting injury to the trigeminal nerve. Patients were followed using standard neurologic testing during the period immediately following implant placement through 6 months. Four hundred five implants were placed in 43 female and 51 male patients. Implant length selection was based on panoramic radiographs using known markers to correct for distortion. In 13 of the patients, the mandibular canal was not adequately visualized, and a computed tomography (CT) scan was used to plan the implant locations. Implants were selected to be located 2 mm above the inferior alveolar canal based on the panoramic images and 1 mm above the canal based on CT images. RESULTS: Eight patients reported altered nerve sensation at their first postimplant visit (8.5%). None of the patients experienced hyperesthesia or dysesthesia. Four of the eight patients with altered sensation had no objective findings or decreased nerve function. One of the patients remained totally anesthetic for 2 months, but reported return to normal function at 4 months. CONCLUSIONS: These findings indicate that a small percentage of patients experience altered sensation after the placement of mandibular endosseous implants. Unlike previous studies, no permanent altered sensation was found. By using proper treatment planning, one can offer endosseous implants with minimal risk of injury to the trigeminal nerve.
In a prospective study (January 1999 to December 1997), 34 patients with 26 mandibular and 20 midfacial fractures were investigated. All the fractures were managed by osteosynthesis. To evaluate the incidence and duration of recovery of post-traumatic and postoperative sensory disturbances, the following tests were carried out: sharp/blunt testing, and the two-point discrimination test as conventional clinical examination methods, and electromyographic recording of the masseter reflex to calibrate the clinical findings. To establish the sensory status of the inferior alveolar and the infraorbital nerves in the region of the fracture, and on the intact and control sides, the tests were performed pre-operatively and postoperatively on the seventh day, after 4 weeks and after 3, 6 and 12 months. The incidence of post-traumatic sensory disturbance was 46% for mandibular fractures and 65% for fractures to the midface (sharp/blunt test, two-point discrimination test). The rate of postoperative sensory disturbance in surgical treatment of mandibular fracture involving the region of the intra bony course of the inferior alveolar nerve, including the post-traumatic sensory disturbance, was 76.9%, and 55% following surgical treatment of midfacial fractures. The incidence of persistent sensory disturbances following surgical treatment was 7.7% in the case of mandibular fractures, and 15% in the case of midfacial fractures (sharp/blunt test, two-point discrimination test, masseter reflex). Recovery of neurological function is delayed in the presence of a displaced fracture (> 1 mm) as compared with non-displaced fractures. For the postoperative calibration of sensory disturbances, electromyographic recording of the masseter reflex from the fourth postoperative week onwards has proved useful.
The infraorbital nerve was sectioned and the ipsilateral whisker follicles were cauterized in hamsters within 12 h of birth. Sixty to ninety days later application of HRP to the proximal stumps of the ipsilateral lingual, inferior alveolar, mylohyoid and auriculotemporal nerves resulted in increased numbers of labeled somata in trigeminal ganglion regions which contain primarily infraorbital cell bodies in normal animals. The labeled central processes of mandibular nerves also occupied portions of the brainstem trigeminal complex normally innervated by infraorbital axons. These findings represent the first anatomical demonstration of trigeminal primary afferent plasticity.
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The trigeminal ganglion, roots and the initial portion of the ophthalmic, maxillary and mandibular nerves were dissected in 3 cadavers, to study the number, area and composition of the fascicles, and the density and diameter spectra of myelinated fibers. The total number of fibers (x 1000) was 26 in the ophthalmic, 50 in the maxillary, and 78 in the mandibular division, 7.7 in the motor root and 170 in the sensory root. In all nerves, the histograms of fiber diameter had a bimodal distribution. Cutaneous and muscle nerve fascicles clearly differed in the fiber density and diameter. The ophthalmic and maxillary nerves (cutaneous) had similar fascicles, and their maximum fiber diameter averaged 14.5 microns. Most fascicles of the mandibular nerve (probably cutaneous fascicles) closely resembled those of the ophthalmic and maxillary nerves, but in some fascicles (probably muscle nerves) the fibers were larger, with a maximum diameter of 19.3 microns. The findings in the three peripheral divisions agree with electrophysiological data about sensory and motor conduction in human trigeminal nerves. The observation that the ophthalmic and maxillary nerves have similar fiber spectra indicates that a special fiber composition does not account for the sparing of the ophthalmic division in trigeminal neuralgia. The absence of very large (A alpha) fibers in the sensory root does not support the view that impulses from muscle spindles are conducted along this root.
Tumours at the skull base may show perineural infiltration of the mandibular nerve. Subsequent retrograde spread into the cavernous sinus, Gasserian ganglion, the trigeminal nerve and the pons may be seen. The patient, a known and treated case of nasopharyngeal carcinoma (NPC), complained of trigeminal neuralgia and difficulty in chewing. Magnetic resonance imaging (MRI) revealed a Gasserian ganglion and trigeminal infiltration with resultant atrophy of the muscles innervated by the mandibular nerve. Proximal cranial nerve involvement should be suspected in patients with skull base malignancy presenting with trigeminal neuralgia. MRI is the modality of choice in delineating the pathological process.
The myofiber type composition was studied in 42 different muscles of the dog to determine if there are unique features that might explain the preferential involvement of the muscles of mastication by inflammatory myopathies. The principal myofiber types for most muscles studied were type 1 and type 2A and, to a lesser extent, type 2C, whereas the dorsal group of muscles innervated by the mandibular nerve (Mm. temporalis, and tensor veli palatini) was composed only of type 2C myofibers and a variant of the type 1 myofiber whose staining intensity was not fully reversed after preincubation in acid media. The distribution of this myofiber type composition was associated with the innervation and embryologic development of the dorsal muscles innervated by the mandibular nerve. This unique myofiber type composition could provide the basis for the preferential susceptibility of these muscles to agents (e.g., immune and/or infectious) that produce myositis; however, further studies are required to assess that possibility.
Systemic or intraventricular administration of cannabinoids causes analgesic effects, but relatively little is known for their cellular mechanism. Using brainstem slices with the mandibular nerve attached, we examined the effect of cannabinoids on glutamatergic transmission in superficial trigeminal caudal nucleus of juvenile rats. The exogenous cannabinoid receptor agonist WIN 55,212-2 (WIN), as well as the endogenous agonist anandamide, hyperpolarized trigeminal caudal neurones and depressed the amplitude of excitatory postsynaptic potentials (EPSPs) or currents (EPSCs) monosynaptically evoked by stimulating mandibular nerves in a concentration-dependent manner. The inhibitory action of WIN was blocked or fully reversed by the CB1 receptor antagonist SR 141716A. WIN had no effect on the amplitude of miniature excitatory postsynaptic currents (mEPSCs) recorded in the presence of tetrodotoxin or cadmium. The inhibitory effect of WIN on EPSCs was greater for those with longer synaptic latency, suggesting that cannabinoids have a stronger effect on C-fibre EPSPs than on Adelta-fibre EPSPs. Ba2+ (100 microm) blocked the hyperpolarizing effect of cannabinoids, but did not affect their inhibitory effect on EPSPs. The N-type Ca2+ channel blocker omega-conotoxin GVIA (omega-CgTX) occluded the WIN-mediated presynaptic inhibition, whereas the P/Q-type Ca2+ channel blocker omega-agatoxin TK (omega-Aga) had no effect. These results suggest that cannabinoids preferentially activate CB1 receptors at the nerve terminal of small-diameter primary afferent fibres. Upon activation, CB1 receptors may selectively inhibit presynaptic N-type Ca2+ channels and exocytotic release machinery, thereby attenuating the transmitter release at the trigeminal nociceptive synapses.
BACKGROUND & OBJECTIVE: With the general using of computed tomography (CT) and magnetic resonance imaging (MRI), it is important to determine which method is more sensitive in detecting the skull base encroachment in clinic. This article was designed to investigate the diagnostic value of CT and MRI in detecting the skull base erosion in nasopharyngeal carcinoma patients. METHODS: Sixty-one cases pathologically proven as nasopharyngeal carcinoma were selected from August 1993 to September 2001. three-dimensional reconstruction with spiral CT thin slices scan were performed in 8 cases. CT scan was performed with Elscient CT Twin Flash; axial scan was parallel to the OM line routinely from soft palate to the suprasellar cistern. There were 13 cases with enhancement scan. MRI scan was performed by Philips T5-II super-conducting magnetic resonance imaging system (0.5T). The standard quadrature head coil was used. Routine axial, sagittal, and coronal image with SE sequences were obtained. Scanned field ranged from the soft palate to the suprasellar cistern. After plain scan, enhanced scan was performed in 55 of 61 cases. RESULTS: MRI discovered the skull base encroached more precisely than CT, 17 cases by CT and 26 cases by MRI, respectively. The early bone marrow infiltration was seen at clivus, basilar pterygoid, and basilar sphenoid in 6 cases by MRI scan while CT scan showed no abnormal lesion at these sites. In addition, MRI revealed nasopharyngeal carcinoma tissue infiltrated along the mandibular nerve (3 cases) while CT scan showed no change of these structures. CONCLUSION: Both CT and MRI can reveal that the tumor encroaches on the skull base by either destroying the bony structure or breaking through the natural foramen. MRI is more sensitive than CT in detecting the skull base encroachment. MRI could reveal the early infiltration of the bone marrow and tumor infiltration along the mandibular nerve. MRI confirms the dimension of nasopharyngeal carcinoma more precisely than CT. The three dimension reconstructional spiral CT was directer in discovering the dimension of the tumor.
Incomplete or complete ossification of the pterygospinous ligament is uncommon. Entrapment of mandibular nerve and its branches was reported due to this anatomical variation, when found. The aim of the present study is to investigate the incidence of the pterygospinous bony bridges in Indian dry skulls. A total of 416 adult dry skulls of Indian origin were studied. In 9.61% of the samples the pterygospinous bony bars were found, out of which 5.76% was complete and 3.84% was incomplete. Such variations are of clinical significance while dealing with mandibular nerve and its branches and various clinical symptoms related to it.
Studies using a brainstem-spinal cord preparation isolated from newborn rats have provided substantial information on neuro-physiology, -pharmacology and -anatomy of the respiratory center, such as mechanisms of respiratory rhythm generation, development of a respiratory center or respiratory reflex [T. Murakoshi, T. Suzue, S. Tamai, A pharmacological study on respiratory rhythm in the isolated brainstem-spinal cord preparation from newborn rat, Br. J. Pharmac. 86 (1985) 95-104 [5]; H. Onimaru, A. Arata, I. Homma, Primary respiratory rhythm generator in the medulla of brainstem-spinal cord preparations from newborn rats, Brain Res. 445 (1988) 314-324 [6]; H. Onimaru, I. Homma, Whole cell recordings from respiratory neurons in the medulla of brainstem-spinal cord preparations isolated from newborn rats, Pflügers Arch. 420 (1992) 399-406 [7]; J.C. Smith, K. Ballanyi, D.W. Richter, Whole-cell patch clamp recordings from respiratory neurons in neonatal rat brainstem in vitro, Neurosci. Lett. 314 (1992) 153-156 [10]; T. Suzue, Respiratory rhythm generation in the in vitro brainstem-spinal cord preparation of the neonatal rat, J. Physiol. (London) 354 (1984) 173-183 [11], reviewed in H. Onimaru, A. Arata, I. Homma, Neuronal mechanisms of respiratory rhythm generation: An approach using in vitro preparation, Jpn. J. Physiol. 47 (1997) 385-403 [8]]. Recently, the dissecting method of the preparation was modified to introduce a brainstem preparation with the trigeminal primary afferents attached for pain studies [M. Hamba, Repetitive stimulation potentiated the stimulus-evoked firing in the trigeminal caudalis-in vitro study. Neurosci. Res. 20 (1996) s163 [2]; M. Hamba, Stimulation-induced responses of the trigeminal caudal neurons in the brainstem preparation isolated from newborn rats, Brain Res. 785 (1998) 66-74 [3]]. As reported previously [3], the activity-dependent change in the excitability of pain-processing neurons, wind-up phenomenon, was studied in the trigeminal caudalis by stimulating the mandibular nerve, using a modified brainstem preparation isolated from newborn rats. The caudalis, the medulla dorsal horn, is known as the center for processing pain and sensory information from the cranio-facial area. The results indicated that the brainstem preparation is applicable for studies on the neuroplasticity at the pain-processing synapses. Here, we describe the method for isolation of a brainstem preparation with the trigeminal mandibular nerve attached and for recording the synaptic response evoked in the caudal neurons, using a whole-cell patch clamp technique. In the present study, we demonstrated repetitive stimulation-induced responses of caudal neurons at postnatal day 1 as an example showing the feasibility of the preparation for pain studies.
Extracts of the locust (Locusta migratoria) mandibular closer muscle separated on reverse-phase HPLC and tested for bio-activity on the locust oviduct contain a bio-active substance that coelutes with authentic proctolin. Furthermore, the effect on oviduct contractions of this compound is indistinguishable from that of authentic proctolin. Antiserum to proctolin stains numerous axons with beaded endings that run along the fibres of the closer muscles and, in addition, the antiserum stains a number of cell bodies in the suboesophageal ganglion, some of which have axons in the mandibular nerve that innervates the mandibular musculature. The function of proctolin appears to be modulatory as its presence significantly increases the amplitude of neurally evoked contractions of the closer muscle. This effect can be mimicked by the addition of inositol 1,4,5-trisphosphate (IP3) to preparations in which the muscles have been permeabilized with dimethyl sulfoxide. The involvement of this second messenger is further implicated as we also show that proctolin produces a large, significant increase in the IP3 content of homogenized muscle.
BACKGROUND AND PURPOSE: The incidence of cranial and/or cervical nerve injuries after primary carotid endarterectomy (CEA) ranges from 3% to 48%; however, the clinical outcome of these injuries after repeat CEA has not been thoroughly analyzed in the English-language medical literature. This prospective study analyzes the incidence and outcome of cranial nerve injuries after repeat CEA. PATIENTS AND METHODS: This study includes 89 consecutive patients who had repeat CEAs. Preoperative and postoperative cranial nerve evaluations were performed, including clinical examinations (neurologic) and direct laryngoscopy. Patients with vagal or glossopharyngeal nerve injuries also underwent comprehensive speech evaluations, video stroboscopy, fluoroscopy, and methylene blue testing for aspiration. Patients with postoperative cranial nerve injuries were followed up for a long time to assess their recovery. RESULTS: Twenty-five cranial and/or cervical nerve injuries were identified in 19 patients (21%). They included 8 hypoglossal nerves (9%), 11 vagal nerves or branches (12%) (6 recurrent laryngeal nerves [7%], 3 superior laryngeal nerves [3%], and 2 complex vagal nerves [2%]), 3 marginal mandibular nerves (3%), 2 greater auricular nerves (2%), and 1 glossopharyngeal nerve (1%). Twenty-two (88%) of these injuries were transient with a complete healing time ranging from 2 weeks to 28 months (18 of 22 injuries healed within 12 months). The remaining three injuries (12%) were permanent (1 recurrent laryngeal nerve, 1 glossopharyngeal nerve, and 1 complex vagal nerve injury). The recurrent laryngeal nerve injury had a longer healing time than the other cranial nerve injuries. CONCLUSIONS: Repeat CEA is associated with a high incidence of cranial and/or cervical nerve injuries, most of which are transient. However, some of these have a long healing time, and a few can be permanent with significant disability.
The number of heads possessed by the lateral pterygoid muscle was investigated in the dog. Only a single head was observed which it is suggested may correspond to the lower head in other mammals. It inserted both onto the condyle and into the articular disc. The nerve which innervated this muscle arose directly from the mandibular nerve, separate from the medial pterygoid nerve. Because of this, it should be termed the lateral pterygoid nerve and not the pterygoid nerve.
The authors have studied the anatomic variations of the inferior alveolar nerve (N. alveolaris inferior) in 18 human heads. The mandibular nerve being free by medial abord. At about half of the studied cases the M. pterygoideus medialis presents a widened insertion extending on the posterior border of the Ramus mandibulae. Before entering into the mandibular channel the inferior alveolar nerve separated from the next elements by expansion of "aponévrose interptérygoidienne". At this level gets sympathic branches from the plexus caroticus externus et internus, making a plexiform structure interfering sometimes a vegetative ganglion formation. At 16.6% of the cases between the alveolar inferior nerve and the lingual nerve are established connection bridges more or less developed. They have an asymetric aspect. There were observed evident connections between the inferior alveolar nerve and the auriculotemporal nerve taking a mono- or pluriradicular form. The mylohyoidian nerve on his homonymous way gives 2--3 sensitive, or vegetative branches to the bone. Practically speaking are important the branches coming from the precanalicular portion of n. alveolaris inferior perforating the periost and penetrating independently in to mandibula through separated vents. These results are practically useful in Stomatological technique explaining from an anatomically point of view the inefficiency of mandibular anaesthesia in some cases although it is correctly applied.