内側型高位頚静脈球の側頭骨形態学的観察

Abstract

Recently medial high jugular bulb, which is an anomaly of the jugular vein protruding into the posterior wall of the internal auditory canal, is believed to cause clinical symptoms, such as sensorineural hearing loss, tinnitus and Meniere's disease. Several articles have discussed this hypothesis on the basis of computed tomography findings. We used computed tomography to examine 188 patients and reviewed serial horizontal sections of 293 temporal bones from patients aged 3 to 85 years.Medial high jugular bulbs were classified into 3 types according to the position: Type I (below the round window niche); Type II (between the round window niche and the floor of the internal auditory canal); Type III (above the floor of the internal auditory canal). Type II and Type III are considered to be clinical medial high jugular bulb.The following analyses were performed: frequency, side (right or left), diameter of the internal auditory canal and vestibular aqueduct, degree of development of periaqueductal pneumatization. We also correlated medial high jugular bulb and clinical symptoms.1) Medial high jugular bulb (Type II, Type III) was observed in 32.2% of CT scans and in 14.3% of temporal bones.2) In temporal bones, Type II was more often seen on the right side and Type III on the left side, but in CT scans both types were more often seen on the right.3) Among the three types, there was no significant difference in the diameter of the internal auditory canal and vestibular aqueduct.4) The degree of development of the periaqueductal pneumatization seemed to correlate with the height of the medial high jugular bulb.5) Stenosis of the internal auditory canal and bony dehiscence of the vestibular aqueduct were seen in some Type II as well as Type III patients.6) There is a possibility that medial high jugular bulb causes some clinical otologic symptoms.