Abstract
The audiograms in 102 cases of head trauma have been classified in 8 types (Kawata), with use of the NY-A audiometer and Onchi's ear-plung-method of bone conduction on the other hand the lack of vitamin B1 has been examined by colouric reaction of urinary pyruvic acid (by Sawada).
C (abrupt) type was most frequently observed, then B (horizontal) A (normal), and D (descendent) type, the last being dip type. Amang them the hard of hearing in 84. 8 %, the perceptive deafness observed in half of them.
In the cases of head trauma at the temporal region the mixed or the conductive deafness was more often, while in the cases of trauma at the face or the nasal radix, the perceptive deafness was predominant. The severe trauma resulted in the mixed, or frequently resulted in the perceptive deafness of C type or dip type.
The C5dip was often caused by a slight trauma at the face or at the nasal radix. The head trauma, in spite of its localization causes the bilateral impairment of hearing: for example, four cases of Contre Coup, out of 64 cases of which trauma was got unilaterally, were observed.
From a fact that B1-avitaminosia can be observed in 68. 1 % of cranial trauma, the lack of vitamin B1 may be an important factor for producing the hearing impairment due to commotio labyrinthi.
