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PubMed1987

Vertigo and masseter paresis. A new local brainstem syndrome probably of vascular origin.

Two patients are reported with symptoms and signs of peripheral vestibular dysfunction, including severe rotatory vertigo, abolished caloric response in the involved ear, and spontaneous nystagmus with the fast component away from that ear. In addition, paresis of the masseter, temporal, and pterygoid muscles and impairment of the masseter reflex were found on the affected side. It is suggested that the vertigo and masseter paresis syndrome is a brainstem syndrome which is probably due to a vascular lesion affecting a very small dorsolateral pontine area.

Aged↗
PubMed1983

Ganglioradiculitis in the dog. A clinical, light- and electron-microscopic study.

Facial hypalgesia, sensory ataxia, depression of tendon reflexes, and masticatory muscle wasting developed acutely to subacutely in three adult dogs. These deficits were correlated with craniospinal sensory ganglioradiculitis. CNS degeneration in the dorsal funiculus, spinal tract of the trigeminal nerve, and solitary tract was secondary to loss of primary sensory neurons. Megaesophagus, which occurred in two dogs appeared to be associated with loss of vagal primary afferent neurons; however, esophageal and gastric myenteric ganglionitis was also observed in one of these animals. In the three dogs changes in the sensory ganglia and roots included non-suppurative inflammation and degeneration and loss of neurons. Perivenular and perineuronal mononuclear infiltrates were prominent. EM study revealed that the satellite cells around degenerating and necrotic cell bodies were commonly invaded and displaced by lymphocytes and macrophages. It was not clear whether these mononuclear cells effected neuronal degeneration or merely responded to it. Although the pathogenesis remained undefined, the similarity of the clinical and pathologic findings in these dogs indicated a nosologic entity that had not been reported previously. This canine ganglioradiculitis was compared with inflammatory disorders of the cranial and spinal ganglia in man.

Animals↗
PubMed1998

Anterior disk displacement of the temporomandibular joint. Significance of clinical signs and symptoms in the diagnosis.

In order to examine the diagnostic significance of typical clinical symptoms in temporomandibular joint (TMJ) disorders for diagnosis of anterior disk displacement, clinical findings were compared with the degree of disk displacement in 84 TMJs of 59 patients with TMJ disorders, who were examined clinically and by means of magnetic resonance imaging (MRI). The control group consisted of 31 subjects with no TMJ symptoms. No significant correlation between the degree of anterior disk displacement and palpation pain of the masticatory muscles or clicking/crepitus of the TMJ could be found. Joint clicking was observed in 65% of patients with TMJ symptoms in normal disk position (NDP). The percentage of joint clicking was almost the same in patients with anterior disk displacement with reposition (ADWR) (68%). There were significant correlations between active mouth opening and disk position as well as between a history of pain and disk position. Patients with NDP and ADWR had almost identical mouth opening values: 48 (+/- 5) mm and 46 (+/- 5) mm respectively. In contrast to these groups the mean values decreased significantly to 42 (+/- 6) mm in patients with anterior disk displacement without reposition (ADWOR). There were no significant correlations between occlusal findings (centric relation and habitual relation, early occlusal contacts, abrasion facets) and disk position when viewed either collectively or individually.

Adult↗
PubMed1994

Facial motor responses evoked by direct electrical stimulation of the trigeminal root. Localizing value for radiofrequency thermorhizotomy.

In Sweet's description of RF-thermocoagulation for trigeminal neuralgia, the trigeminal nerve was stimulated at 50 c/s to evoke paraesthesias, in order to check the electrode location before the thermolesion is made. In 1979, we changed the frequency to 5 c/s, so as to produce in addition twitches in the masticatory muscles (in stead of the less detectable tetanization produced by 50 c/s stimulation). Since then, we started to observe, also, twitches in the muscles innervated by the facial nerve. These twitches were not always in the Orbicularis oculi (which corresponds to the classical blink reflex), but also in the lower facial muscles. Such clinically observable evoked motor responses (EMR)-which had not been reported before--were noticed in 44% of the 459 procedures performed from 1979 to 1988. When EMR were present, the threshold to evoke paraesthesias before thermolesion, and the duration of the thermolesion for obtaining a marked hypoaesthesia covering the entire painful territory, were significantly lower, respectively p < 0.01 and p < 0.001, than when EMR were absent. This indicates that the electrode was closer to the nerve when EMR were present. As a probable consequence, recurrence of pain was significantly lower in the EMR (+) group: 1.4%, than in the EMR (-) group: 5.8% (p < 0.05). The twitches corresponded to the territory of the evoked paraesthesias in 95%, and to the hypoaesthetic area created by the thermolesion in 96%. So, getting EMR in the territory of the pain can be a helpful indicator for an accurate location of the electrode in the trigeminal root, according to its somatotopic organization. These EMR are hypothesized to be due to a trigemino-facial reflex. A preliminary intra-operative EMG study clearly shows that for EMR in the upper part of the face we are dealing with blink-like reflexes, whilst for EMR in the lower face, mechanisms still remain unclear and need further study to be understood.

Adult↗
PubMed1989

Immunocytochemical analysis of the perinatal development of cat masseter muscle using anti-myosin antibodies.

The developmental changes in myosin gene expression in the masseter muscle of embryonic and juvenile kittens were examined immunocytochemically using anti-myosin heavy chain antibodies of various specificities. In the mature cat, this muscle contains only two phenotypes, the majority of fibres are superfast, the rest being slow fibres. In foetal tissues, the histological appearance of bundles of myotubes, comprising a large central myotube surrounded by a rosette of smaller myotubes, strongly suggest the existence in the jaw muscle of primary and secondary fibres during development. Immunocytochemical data are consistent with the hypothesis that there are four types of fibre; two types of primary fibre as well as two types of secondary fibre. (1) Slow primaries stain strongly with an anti-slow myosin antibody throughout the period under study. These fibres transiently express embryonic but not foetal myosin. (2) Superfast primaries stain for embryonic/foetal and slow myosins in the perinatal period but progressively replace these myosins with superfast myosin during postnatal development. (3) Superfast secondaries initially express embryonic/foetal myosins, but later, beginning around the time of birth progressively replace these myosins with superfast myosin. These fibres do not express slow myosin. (4) Slow secondaries, which initially also express embryonic/foetal myosins, but which postnatally express slow or slow and superfast myosins and express only slow myosin in the adult. These four types of fibres are homologous to the four isotypes of limb muscle fibres and may be derived from distinct lineages of myoblasts.

Animals↗
PubMed1989

The human temporo-mandibular joint: current anatomic and physiologic status.

The aim of this study was to take stock of current anatomic and physiologic knowledge of the human temporo-mandibular joint. Though the lateral pterygoid m. plays an essential role in joint movements, we believe that the small deep portion of the masseter and temporalis have a supplementary action in guiding the articular disc forward. The embryologists have demonstrated joint movements in the two-month embryo and at this stage there already exists a triple attachment of the temporalis, pterygoid and masseter to the disc.

Adult↗
PubMed1994

Chronic illness of the temporomandibular joints as experienced by support-group members.

PURPOSE: For temporomandibular disorders, the clinical situation is one of considerable etiologic, diagnostic, and therapeutic uncertainty. Using interview data, this report describes this condition and the search for care from the perspective of sufferers who are support-group members. PARTICIPANTS AND METHODS: Thirty-two individuals participated; all were members of a support group for individuals with long-term problems attributed to the temporomandibular joints and/or the surrounding masticatory muscles. Using a structured, open-ended interview format, this study investigated how individuals understand and give meaning to their symptoms, their patterns of care seeking, and the consequences of the illness on their lives. The participants also completed several structured questionnaires. RESULTS: For these support-group members, symptoms extended beyond the jaw and surrounding area, with extensive musculoskeletal involvement and resulting dysfunctions that have far-reaching consequences for the sufferers' lives. Primary care physicians are often consulted, especially early in the illness history. They also provide ongoing care and are asked for guidance when patients seek specialized treatment. A striking aspect of the findings from the interviews is the complex and costly pattern of health care seeking. This extended search for effective treatment is examined with reference to culturally based understanding, shared by patients and clinicians, about the nature of illness.

Adult↗
PubMed1990

Dose-related effects of succinylcholine on the adductor pollicis and masseter muscles in children.

This study was performed to determine the effects of various doses of succinylcholine on resting tension and evoked twitch height at the masseter and adductor pollicis muscles in children. Twenty patients, aged 3-10 yr, ASA physical status I or II, were randomly assigned to receive succinylcholine 0.15, 0.25, 0.50 or 1.00 mg.kg-1, during halothane-nitrous oxide anaesthesia. Supramaximal train-of-four stimulation was applied simultaneously to the ulnar nerve and the nerve to the masseter. Transducers recorded force at the jaw and the thumb. Maximum blockade of the first twitch (T1) and maximum resting tension change were measured. Potency of succinylcholine at the two muscles was estimated by linear regression of the logit transformation of T1 versus log dose. The relationship between resting tension change and log dose was established by linear regression. The masseter muscle was more sensitive to succinylcholine than the adductor pollicis with an ED95 of 0.28 +/- 0.02 (mean +/- SEM) vs 0.44 +/- 0.05 mg.kg-1 (P less than 0.05). Onset of neuromuscular blockade was faster at the masseter, and recovery occurred simultaneously in both muscles. A dose-related increase in resting tension was observed in both muscles, but its magnitude was five times greater at the masseter. With succinylcholine, 1 mg.kg-1, this increase was 51.6 +/- 16.8 g at the masseter and 9.1 +/- 2.3 g at the adductor pollicis. Tension returned to baseline within 1-2 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1990

Potency of atracurium on masseter and adductor pollicis muscles in children.

The sensitivity of the masseter to atracurium was measured in ten children aged 3-10 yr undergoing elective surgery, and compared with that of the adductor pollicis. During nitrous oxide-halothane anaesthesia and mechanical ventilation, supramaximal nerve stimulation was applied to the ulnar nerve at the elbow and to the nerve to the masseter, at a point inferior to the zygomatic arch, anterior to the mandibular condyle. Jaw closure was measured by a force displacement transducer system attached to an oral airway and connected to a metal frame fixed to the operating table 10 cm caudad to the chin. Cumulative dose-response curves for atracurium were obtained by the injection of doses followed by an infusion to compensate for elimination. The mean ED50s and ED95s were similar at the masseter and the adductor pollicis. At the masseter, these were 0.150 +/- 0.013, mean +/- SEM, mg.kg-1 and 0.254 +/- 0.021 mg.kg-1, respectively. At the adductor pollicis, corresponding values were 0.145 +/- 0.009 mg.kg-1, and 0.259 +/- 0.016 mg.kg-1. However, this relationship was not constant in every patient, and in some patients the masseter was much more sensitive than the adductor pollicis. The time from injection of the first dose of atracurium to maximum blockade was 2.5 +/- 0.2 min at the masseter and 3.2 +/- 0.2 min at the adductor pollicis (P less than 0.05). It is concluded that when atracurium is administered to paediatric patients, neuromuscular blockade is usually of the same intensity at each muscle but occurs sooner at the masseter than at the adductor pollicis.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1990

Malignant hyperthermia susceptibility in adult patients with masseter muscle rigidity.

We sought to determine the incidence of malignant hyperthermia (MH) susceptibility in adult patients with a previous episode of masseter muscle rigidity (MMR). The medical records and in vitro contracture test results of all patients over 15 years of age tested for MH because of previous MMR from 1985 to 1988 were reviewed. The number of children (age less than 16 yr) tested for MH because of previous MMR was also determined for the same four-year period, for comparison of coincidence rates. Six of 24 adult patients (25 per cent) were proved MH-susceptible by in vitro contracture testing. No clinical sign associated with the episode of MMR was predictive of MH-susceptibility. Two of six MH-susceptible patients developed acute MH following MMR. In the same four-year period, 75 children were tested for MH-susceptibility because of previous MMR; 44 (59 per cent) had a positive in vitro contracture test. We conclude that the coincidence of MMR and MH-susceptibility is lower in adults than children. Episodes of acute MH do occur after MMR, but the onset of MH may be delayed. Conservative management of MMR in adult patients is recommended.

Adult↗
PubMed1982

Masseter spasm induced by succinylcholine in children: contracture testing for malignant hyperthermia: report of six cases.

We evaluated six boys who had developed isolated masseter muscle spasm following intravenous succinylcholine. All were receiving halothane by inhalation.l In vitro muscle contracture tests utilizing halothane and caffeine were performed. Four of the six boys had contracture response similar to those of malignant hyperthermia susceptible patients. Rigidity following succinylcholine should prompt the clinician to consider malignant hyperthermia but has been associated with other myopathic conditions as discussed.

Anesthesia↗
PubMed1982

[Masseter spasm].

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Anesthetics↗
PubMed1996

The pterygoid venous plexuses.

The pterygoid venous plexuses are closely adjacent to the lateral pterygoid m. and occupy a considerable part of the infratemporal fossa (ITF). We have conducted a study after injection of colored latex in 10 unemblamed subjects in order to define the arrangement of the venous network and to assess the frequency of the different types of plexuses found. In all the subjects symmetry was noted between the right and left plexuses, with predominance of the venous layer in the upper part of the ITF. The pattern most often encountered was plexiform and complex. The development of these plexuses follows that of the masticatory muscles, whose contraction promotes drainage and represents an alternative venous pathway for drainage of the cranial cavity.

Cadaver↗