Brainstem Excitability is Increased in Subjects with Palmomental Reflex
The palmomental reflex (PMR) is a brief contraction of the mentalis muscles caused by a scratch over the thenar eminence, i.e. a brainstem reflex to afferents of upper limb. Using electrophysio-logic methods, we studied the characteristics of brainstem excitability in PMR subjects. Methods: Ten heal...
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2007-08-01
|
| Series: | Journal of the Formosan Medical Association |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0929664608600169 |
| _version_ | 1818142999782096896 |
|---|---|
| author | Kwong-Kum Liao Jen-Tse Chen Kuan-Lin Lai Chia-Yi Lin Chih-Yang Liu Chuen-Der Kao Yung-Yang Lin Zin-An Wu |
| author_facet | Kwong-Kum Liao Jen-Tse Chen Kuan-Lin Lai Chia-Yi Lin Chih-Yang Liu Chuen-Der Kao Yung-Yang Lin Zin-An Wu |
| author_sort | Kwong-Kum Liao |
| collection | DOAJ |
| description | The palmomental reflex (PMR) is a brief contraction of the mentalis muscles caused by a scratch over the thenar eminence, i.e. a brainstem reflex to afferents of upper limb. Using electrophysio-logic methods, we studied the characteristics of brainstem excitability in PMR subjects.
Methods: Ten healthy PMR subjects were included in the study. Brainstem excitability was assessed with electrical stimulation at the trigeminal nerve, median nerve, ulnar nerve, and sural nerve with recordings at the mentalis muscles. A comparison was made by the probability between the mechanical scratch and the electrical stimulation to evoke the visible muscle contraction of mentalis.
Results: An electrical stimulus was able to elicit mentalis muscle responses (MMRelectrical) in all the subjects if the stimulus was of sufficient strength. Using electrical stimulation, the median nerve at the wrist was the best site to evoke MMRelectrical. However, in PMR subjects, the probability of MMRelectrical to median nerve stimulation was less than that of MMRscratch, i.e. the clinical findings of PMR. Significantly lower thresholds and higher amplitudes were noted in PMR subjects only when the median nerve was stimulated. The onset latency did not show any difference between the two groups despite the stimulation sites.
Conclusion: The facial motor neurons to median nerve stimulation are more sensitive in PMR subjects. In healthy PMR subjects, this indicates that the excitability increases only in the specific neuronal circuits between the lower cervical spinal cord and the facial motor nucleus in the rostral medulla. MMRelectrical is a physiologic phenomenon, and PMR is a sign of increased brainstem excitability. |
| first_indexed | 2024-12-11T11:24:42Z |
| format | Article |
| id | doaj.art-e19dbe46819c4465bb9a18e71c299ec4 |
| institution | Directory Open Access Journal |
| issn | 0929-6646 |
| language | English |
| last_indexed | 2024-12-11T11:24:42Z |
| publishDate | 2007-08-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of the Formosan Medical Association |
| spelling | doaj.art-e19dbe46819c4465bb9a18e71c299ec42022-12-22T01:09:03ZengElsevierJournal of the Formosan Medical Association0929-66462007-08-01106860160710.1016/S0929-6646(08)60016-9Brainstem Excitability is Increased in Subjects with Palmomental ReflexKwong-Kum Liao0Jen-Tse Chen1Kuan-Lin Lai2Chia-Yi Lin3Chih-Yang Liu4Chuen-Der Kao5Yung-Yang Lin6Zin-An Wu7Department of Neurology, Taipei Veterans General Hospital, Taichung, TaiwanDepartment of Neurology, Taipei Veterans General Hospital, Taichung, TaiwanDepartment of Neurology, Taipei Veterans General Hospital, Taichung, TaiwanDepartment of Neurology, Taipei Veterans General Hospital, Taichung, TaiwanDepartment of Neurology, Taipei Veterans General Hospital, Taichung, TaiwanDepartment of Neurology, Taipei Veterans General Hospital, Taichung, TaiwanDepartment of Neurology, Taipei Veterans General Hospital, Taichung, TaiwanDepartment of Neurology, Taipei Veterans General Hospital, Taichung, TaiwanThe palmomental reflex (PMR) is a brief contraction of the mentalis muscles caused by a scratch over the thenar eminence, i.e. a brainstem reflex to afferents of upper limb. Using electrophysio-logic methods, we studied the characteristics of brainstem excitability in PMR subjects. Methods: Ten healthy PMR subjects were included in the study. Brainstem excitability was assessed with electrical stimulation at the trigeminal nerve, median nerve, ulnar nerve, and sural nerve with recordings at the mentalis muscles. A comparison was made by the probability between the mechanical scratch and the electrical stimulation to evoke the visible muscle contraction of mentalis. Results: An electrical stimulus was able to elicit mentalis muscle responses (MMRelectrical) in all the subjects if the stimulus was of sufficient strength. Using electrical stimulation, the median nerve at the wrist was the best site to evoke MMRelectrical. However, in PMR subjects, the probability of MMRelectrical to median nerve stimulation was less than that of MMRscratch, i.e. the clinical findings of PMR. Significantly lower thresholds and higher amplitudes were noted in PMR subjects only when the median nerve was stimulated. The onset latency did not show any difference between the two groups despite the stimulation sites. Conclusion: The facial motor neurons to median nerve stimulation are more sensitive in PMR subjects. In healthy PMR subjects, this indicates that the excitability increases only in the specific neuronal circuits between the lower cervical spinal cord and the facial motor nucleus in the rostral medulla. MMRelectrical is a physiologic phenomenon, and PMR is a sign of increased brainstem excitability.http://www.sciencedirect.com/science/article/pii/S0929664608600169brainstem excitabilityfacial motor neuronmedian nervepalmomental reflex |
| spellingShingle | Kwong-Kum Liao Jen-Tse Chen Kuan-Lin Lai Chia-Yi Lin Chih-Yang Liu Chuen-Der Kao Yung-Yang Lin Zin-An Wu Brainstem Excitability is Increased in Subjects with Palmomental Reflex Journal of the Formosan Medical Association brainstem excitability facial motor neuron median nerve palmomental reflex |
| title | Brainstem Excitability is Increased in Subjects with Palmomental Reflex |
| title_full | Brainstem Excitability is Increased in Subjects with Palmomental Reflex |
| title_fullStr | Brainstem Excitability is Increased in Subjects with Palmomental Reflex |
| title_full_unstemmed | Brainstem Excitability is Increased in Subjects with Palmomental Reflex |
| title_short | Brainstem Excitability is Increased in Subjects with Palmomental Reflex |
| title_sort | brainstem excitability is increased in subjects with palmomental reflex |
| topic | brainstem excitability facial motor neuron median nerve palmomental reflex |
| url | http://www.sciencedirect.com/science/article/pii/S0929664608600169 |
| work_keys_str_mv | AT kwongkumliao brainstemexcitabilityisincreasedinsubjectswithpalmomentalreflex AT jentsechen brainstemexcitabilityisincreasedinsubjectswithpalmomentalreflex AT kuanlinlai brainstemexcitabilityisincreasedinsubjectswithpalmomentalreflex AT chiayilin brainstemexcitabilityisincreasedinsubjectswithpalmomentalreflex AT chihyangliu brainstemexcitabilityisincreasedinsubjectswithpalmomentalreflex AT chuenderkao brainstemexcitabilityisincreasedinsubjectswithpalmomentalreflex AT yungyanglin brainstemexcitabilityisincreasedinsubjectswithpalmomentalreflex AT zinanwu brainstemexcitabilityisincreasedinsubjectswithpalmomentalreflex |