Nerve Growth Factor and Its Receptor System in Rheumatologic Diseases and Pain Management
Siba P. Raychaudhuri, Smriti K. Raychaudhuri, Debasis Bagchi in Psoriasis and Psoriatic Arthritis, 2017
Administration of NGF provokes pain and hyperalgesia. In rodents, NGF causes robust, long-lasting mechanical and thermal hyperalgesia (an increased response to a stimulus that is normally painful) following either local or systemic administration [67,68]. In humans, the ability of NGF to provoke pain came to light in clinical studies to explore its potential in the treatment of polyneuropathies. Subcutaneous injection of NGF into the forearm of healthy volunteers produced allodynia (pain as a result of a stimulus that does not normally cause pain) and hypersensitivity in the surrounding skin that lasted for up to 3 weeks [69], and generalized muscle pain occurred more frequently in subjects who received NGF compared with those who received placebo [70,71]. In a controlled trial of the effects of NGF injection into the masseter muscle of healthy volunteers, local mechanical allodynia and hyperalgesia were observed for at least a week, and pain was observed during strenuous jaw movement [72]. Direct administration of NGF into the sciatic nerve also produces hyperalgesia [73].
Sleep–Wake Disorders
Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw in Hankey's Clinical Neurology, 2020
The diagnosis of sleep bruxism is usually clinical, based on reports of tooth-grinding sounds or jaw clenching during sleep along with one or more of the following: Abnormal wear on the teeth: surface loss, hypersensitive/painful teeth.Jaw muscle discomfort, fatigue, or pain and difficulty opening jaw on awakening.Masseter muscle hypertrophy.No better explanation by another sleep disorder, neurologic disorder, medication, or substance abuse.
Respiratory Changes During Sleep
Alan D. Miller, Armand L. Bianchi, Beverly P. Bishop in Neural Control of the Respiratory Muscles, 2019
The transition from wakefulness to non-REM sleep is accompanied by slight hyperpo-larization or no change in the membrane potential of brainstem and spinal motoneurons.13 In masseter motoneurons, the transition to non-REM sleep is accompanied by decreased tonic action potential generation, with no change in rheobase or input resistance. Motoneurons are hyperpolarized in REM compared with non-REM sleep.13 In the masseter muscle this is accompanied by a loss of action potential generation except for isolated spike potentials during facial twitches and rapid eye movements. Evidence for depressed excitability of the motoneuron includes a lengthened interval between somodendritic and intrasomal spikes, increased rheobasic current, and decreased input resistance with frequent phasic fluctuations coincident with rapid eye movements.13 Additionally, excitatory postsynaptic potential amplitude is suppressed during REM sleep.13
Chewing Entrains Cyclical Actions but Interferes With Discrete Actions in Children
Published in Journal of Motor Behavior, 2021
Jessica Prebor, Brittany Samulski, Cortney Armitano-Lago, Steven Morrison
Chewing rates were determined from changes in the EMG activity of the masseter muscle. The EMG sensor was positioned over the belly of the masseter muscle on the dominant chewing side as determined by the participant at the start of the session. All EMG activity was recorded using the Delsys Trigno system (Delsys, Boston, MA) at a sample rate of 2000 Hz. Processing of the surface EMG signals involved down-sampling the signal to 1000 Hz, rectification and filtering using a second-order low-pass Butterworth filter (cutoff frequency 400 Hz). The number of peaks of the filtered EMG signal, which are reflective of the contraction of the masseter muscle during chewing, were calculated using a purposely designed Matlab algorithm. Accuracy of the results from the algorithm for determining chewing rates was verified by visual inspection of 50% of the trials for each subject. All signal processing was performed using custom software developed in Matlab (Mathworks R14).
Salivary gland carcinomas with unusual presentations
Published in Acta Oncologica, 2019
Carl Frederik Haugaard, Tina Klitmøller Agander, Giedrius Lelkaitis, Kim Francis Andersen, Simon Andreasen, Irene Wessel
A 56-year-old male with no previous medical history was admitted to the emergency ward due to syncope and pre-syncope during the last two days. MRI scan of the cerebrum showed approximately 20, contrast-enhancing tumors in both cerebral hemispheres. CT-scan of neck, thorax and abdomen demonstrated a mass in the left masseter muscle and multiple enlarged ipsilateral small lymph nodes. Ultrasonography showed a 2 × 2 × 1 cm hypoechoic process in the masseter muscle without extra parenchymal growth and several enlarged (>1 cm), round and hypoechoic lymph nodes in level II-IV. 18F-FDG PET-CT scan showed low metabolic activity of all lesions (Figure 2). FNA was uninformative, and a cervical lymph node was excised for diagnosis. Histopathology of the lymph node showed metastatic tumor cells positive for AR, GATA-3, HER2 and gross cystic disease fluid protein-15 (GCDFP-15), thus increasing the probability of salivary gland carcinoma. As a diagnostic measure, the tumor of the masseter muscle was removed.
The diagnosis and management of temporal arteritis
Published in Clinical and Experimental Optometry, 2020
Melvin Lh Ling, Jason Yosar, Brendon Wh Lee, Saumil A Shah, Ivy W Jiang, Anna Finniss, Alexandra Allende, Ian C Francis
Jaw claudication occurs in up to 50 per cent of patients with TA and may be misdiagnosed as temporomandibular joint disorder (TMJD).1997 In TA, jaw claudication is caused by masseter muscle ischaemia and is characterised by pain that develops with or soon after chewing, and subsides with rest. In contrast, TMJD causes jaw pain with any movement, emphasising the difference between the mechanical and ischaemic nature of the pain.2009 Patients with jaw claudication often avoid chewy foods or meat, although this is not a distinguishing feature from TMJD.1991 In one study, 54 per cent of patients with positive temporal artery biopsies had jaw claudication compared with only three per cent who had negative biopsies.1995 Asking a patient to chew gum is a simple method of evaluating jaw claudication,2016 but in the absence of chewing gum in the clinic, the authors simply ask the patient to open and close the jaw rapidly and forcefully 20 times. Jaw claudication alone should not be used to rule in TA due to the potential morbidity associated with steroid treatment, as demonstrated in one case by the authors of mandibular osteomyelitis misdiagnosed as TA.2011
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- Anatomy
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- Zygomatic Bone
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- Parotid Gland
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