Johkura K, Matsumoto S, Hasegawa O, Kuroiwa Y
Department of Neurology, Urafune Hospital, Yokohama City University, Yokohama, Japan.
J Neurol Sci. 1998 Nov 26;161(1):91-6. doi: 10.1016/s0022-510x(98)00261-5.
We report the case of a male patient with a traumatic small hemorrhage partially involving the bilateral inferior colliculi without evidence of a temporal lobe lesion. He was unable to comprehend spoken words although he had intact speech production, reading and writing abilities. Comprehension of environmental sounds was also affected. Among the receptive musical abilities, discrimination of intensity, tone and rhythm were preserved, while recognition of melody was impaired. Audiometry showed normal thresholds for pure tone. Waves I-IV of brainstem auditory evoked potentials were elicited normally, whereas the wave V was elicited with reduced amplitude and prolonged latencies on both sides. The main component of middle latency auditory evoked potentials, which is evoked over both hemispheres by monaural stimulation to either side in normal subjects, was elicited only over the hemisphere contralateral to the ear receiving stimulation. Our patient's auditory findings were similar to those usually found in generalized auditory agnosia. Auditory agnosia is usually considered as a sign of a bitemporal cortical or subcortical disorder, but, in our patient, a brainstem disorder caused a disturbance of auditory recognition similar to auditory agnosia due to a bitemporal lesion. Our patient's auditory findings may belong to the category of a brainstem auditory-processing disorder brought on by a small hemorrhage in the inferior colliculi. In addition, the impairment in our patient implies that, in the neural processing of musical parameters, the decoding of intensity, tone and rhythm is accomplished at the level of inferior colliculus, whereas further cortical processing is necessary for the appropriate recognition of melody.
我们报告了一例男性患者，其外伤性小出血部分累及双侧下丘，无颞叶病变证据。尽管他的言语表达、阅读和书写能力完好，但无法理解口语单词。对环境声音的理解也受到影响。在接受性音乐能力方面，强度、音调和节奏的辨别能力得以保留，而旋律识别受损。听力测试显示纯音阈值正常。脑干听觉诱发电位的I-IV波正常引出，而双侧V波引出时振幅降低且潜伏期延长。在正常受试者中，单耳刺激一侧时，双侧半球均能引出中潜伏期听觉诱发电位的主要成分，而在我们的患者中，仅在接受刺激耳对侧的半球引出该成分。我们患者的听觉表现与通常在广泛性听觉失认症中发现的表现相似。听觉失认症通常被认为是双侧颞叶皮质或皮质下病变的体征，但在我们的患者中，脑干病变导致了类似于双侧颞叶病变所致听觉失认症的听觉识别障碍。我们患者的听觉表现可能属于下丘小出血引起的脑干听觉处理障碍范畴。此外，我们患者的损伤意味着，在音乐参数的神经处理过程中，强度、音调和节奏的解码在下丘水平完成，而旋律的适当识别需要进一步的皮质处理。
