PMC10157069_01
(A-C). Severe hemifacial atrophy on the left side and hypertrophy of the left masseter muscle.
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F1
There was involuntary twitching and hypertrophy of the left masseter muscle and temporalis muscle. There was evidence of facial atrophy in the left corner of the mouth, and the subcutaneous fat on the left side was relatively poor compared to that on the right side, with no other abnormalities found (Figures 1A-C).
(A-F). Images and 3D reconstruction. (A). Reduction in the subcutaneous fat of the left cheek(Red arrow); (B). Left parotid gland atropy (Green arrow); (C). MRI-3D-TOF; (D). MRI-T2; (E,F). 3D reconstruction. A tiny blood vessel runs ventral to the CN V(Purple arrow).
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F2
MRI showed thicker left masticatory muscles compared to the contralateral side, a significant reduction in the subcutaneous fat of the left cheek, and a significantly smaller left parotid gland compared to the contralateral side. (Figures 2A, B). MRI-3D-TOF and MRI-T2 sequences showed that the morphology of both sides of the trigeminal nerve were normal, and no offending blood vessels were found (Figures 2C, D). Reconstruction by the 3D-Slicer software (Figures 2E, F).
(A-G). Intraoperative Situation. (C). The masseter muscle responds to stimulation of Vm1; (D). The lateral pterygoid muscle responds to stimulation of Vm2; (E). Vm1 and Vm2 are cut off by 50%, respectively; (F). Preoperative EMG: Abnormal discharge was mainly in the temporal muscle (masticatory muscle spasm); (G). Postoperative EMG: After selective resection of the motor branch, the abnormal discharge disappeared, and masseter contraction was still observed.
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F3
The trigeminal nerve motor root could be seen to be divided into two branches, with a communicating branch in the middle (Figures 3A, B). The monopolar stimulation technique was used to stimulate the cephalic and caudal branches of the trigeminal nerve motor root, where the individual EMG responses of the masticatory muscles could be recorded (Figures 3C, D), and the contraction of the temporalis and masseter muscles could be observed. 50% of the cephalic and caudal branches of the trigeminal nerve motor root were resected, along with the communicating branch.
Pathological morphology of nerve tissue. (A). Hematoxylin Eosin (A1, A2, A3 x 200); (B). Toluidine Blue (B1, B2, B3 x 200); (C). Methyl Violet (C1, C2, C3 x 200); (D). Massion ( x 200); (E). MGT ( x 200); (F). Van Gieson ( x 200).
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F4
The abnormal discharges in the left masticatory muscles of the patient completely disappeared, although contractions of the temporalis and masseter muscles continued to be present (Figures 4A, B).