Pars Cochlearis Research Articles

The earliest known member of the rorqual—gray whale clade (Mammalia, Cetacea)

ABSTRACT Eobalaenoptera harrisoni, gen. et sp. nov., is described from a partial skeleton collected from the middle Miocene Calvert Formation of Virginia. Characteristics of this taxon, particularly of the petrosal, indicate that the new whale is a member of the clade that includes the Balaenopteridae (rorquals) and Eschrichtidae (gray whales) to the exclusion of “cetotheres” and the Balaenidae (right whales). Some of the probable synapomorphies of this clade include an elongate pars cochlearis, a tubular internal auditory meatus, the greater petrosal nerve foramen on the tympanic side of the petrosal, the stylomastoid fossa extending onto the posterior process of the petrosal, no medial groove on the pars cochlearis, four digits on each forelimb, depressed supraorbital processes, and ascending processes of maxillae extending onto the vertex. The approximate 14-million-year age of the specimen makes it the oldest known member of the clade by some 3 to 5 million years, and extends the fossil record of this clade closer to the divergence time estimated by some recent molecular studies.

定型的症候を示さない聴神経腫瘍例

Acoustic neurinoma can be easily diagnosed by the following symptoms such as progressive unilateral hearing loss, tinnitus, and a feeling of dizziness. It also can be diagnosed by abnormal results of tests such as pure-tone audiometry, auditory brain stem response (ABR), and caloric nystagmus. Recently, with the development of imaging diagnostics, cases of acoustic nerve tumor without these typical symptoms or findings have been reported.This paper reports the following six cases of acoustic neurinoma with atypical symptomology experienced in Tokushima Municipal Hospital: 1) two patients first developed sudden hearing loss,2) one patient had an abnormal tongue sense as the chief complaint,3)two patients had normal hearing, and 4) one patient showed a normal ABR.The nerves of the internal acoustic meatus are the pars superior vesti bularis, pars inferior vestibularis, pars cochlearis, and nervus facialis. Examination methods for all of these nerves except the pars inferior vestibularis have been developed. Acoustic neurinoma often originates in the pars inferior vestibularis. The establishment of an examination method for tumors of this nerve is desirable.