Difference between revisions of "Trigeminal Nervous System Segmentation"

===Trigeminal Brainstem Area===

The trigeminal brainstem area is the most complex area to study and interpret because of the complexity of its multi-synaptic connections. The following electro-physiological tests are objectively sufficient to understand the cryptic language of the SCNS. These will be treated in this section, but they will also be resumed in other editions. The following trigeminal reflexes will be considered: the ''jaw jerk'', the ''mechanical and electrical silent period'', the ''recovery cycle of the masseteric inhibitory reflex'' and the ''laser silent period'', as well as the ''masseteric laser-evoked potentials'' (<translate>Figure</translate> 5).

====Jaw jerk Reflex====

[[File:Riflesso mandibolare.jpg|left|thumb|'''<translate>Figure</translate> 6:''' Mandibular reflex performed with Nihon Kohden instrumentation]]

The piezoelectric trigger is used for the mandibular reflex, though it does not provide controlled reproducibility and quantification of the stimulation intensity; simultaneous recordings of the two sides are considered an essential method for the accurate and acceptable assessment of the asymmetry of the side. Asymmetry in the latency is very small: it ranges from 0 to 0.8 ms with an average of 0.13 ms (SD 0.17) in 131 normal subjects<ref>{{cita libro  

  }}</ref>. Although in trigeminal neuropathy or multiple sclerosis the jaw jerk reflex may be retarded by several milliseconds, asymmetries of latency of only 0.8 ms were considered to be a higher limit of normality in neurological studies (<translate>Figure</translate> 6).

In previous studies about the jaw jerk in patients with cranial-mandibular disorders (TMDs), patients with ''unilateral'' disorders were selected to identify an affection side in which there was a latency delay and a lower amplitude on the side of the mandibular deviation and pain. Even if the maximum mandibular closure force in TMDs can be reduced to half as much as control groups<ref>{{cita libro  

  }}</ref>, several researchers propose that muscular hyperactivity is one of the key mechanisms in cranial-mandibular dysfunction, and that hyperactivity of the masticatory muscles is central to the nervous system. A cortical activity or abnormal reticular system would increase the excitability of the motorneurons directly through the corticobulbar system or indirectly through the modulation of multi-synaptic reflexes of lateral reticular formation. The initial causes could be stress, psychogenic factors, or a primary disease of the central nervous system<ref>{{cita libro  

  }}</ref>, such as the oromandibular dystonia<ref>{{cita libro