Abstracts (from PubMed) of papers reporting loss of speech comprehension following injury of the inferior colliculi Howe JR, Miller CA. Department of Surgery, Section of Neurosurgery, University of Michigan Medical Center, Ann Arbor. Midbrain deafness following head injury. Neurology. 1975 Mar;25(3):286-9. A patient is described who became deaf following a head injury. Postmortem examination revealed bilateral lesions of the lateral lemnisci and inferior colliculi. The clinical pattern of midbrain deafness is examined and compared with syndromes of cortical and peripheral auditory impairment. -- Jani NN, Laureno R, Mark AS, Brewer CC. Department of Neurology, Washington Hospital Center, Washington, DC. Deafness after bilateral midbrain contusion: a correlation of magnetic resonance imaging with auditory brain stem evoked responses. Neurosurgery. 1991 Jul;29(1):106-8; discussion 108-9. A 46-year-old woman became deaf after a closed head injury. When a computed tomographic scan failed to disclose the cause, conversion disorder was suspected. Magnetic resonance imaging, however, showed bilateral contusions of the inferior colliculi, providing objective evidence for an organic cause of hearing loss. Auditory brain stem evoked responses and stapedial reflexes also provided objective evidence of brain stem injury. This case illustrates the phenomenon of dorsal midbrain injury after head trauma. It indicates the sensitivity of magnetic resonance imaging for small focal lesions after head trauma, and it demonstrates some difficulties in the diagnosis of "hysterical" deafness. -- Hu CJ, Chan KY, Lin TJ, Hsiao SH, Chang YM, Sung SM. Department of Neurology of Taipei Municipal Jen-Ai Hospital, Taiwan. Traumatic brainstem deafness with normal brainstem auditory evoked potentials. Neurology. 1997 May;48(5):1448-51. A 48-year-old woman became totally deaf after a head injury. Magnetic resonance imaging showed bilateral contusions around the inferior colliculi and the brainstem auditory evoked potentials (BAEP) failed to show any abnormality. This case demonstrates that small, symmetrical, bilateral lesions around the inferior colliculi may cause deafness and may still be associated with a normal BAEP. -- Johkura K, Matsumoto S, Hasegawa O, Kuroiwa Y. Department of Neurology, Urafune Hospital, Yokohama City University, Yokohama, Japan. Defective auditory recognition after small hemorrhage in the inferior colliculi. J Neurol Sci. 1998 Nov 26;161(1):91-6. 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. -- Masuda S, Takeuchi K, Tsuruoka H, Ukai K, Sakakura Y. Department of Otorhinolaryngology, National Mie Hospital, Tsu, Japan. Word deafness after resection of a pineal body tumor in the presence of normal wave latencies of the auditory brain stem response. Ann Otol Rhinol Laryngol. 2000 Dec;109(12 Pt 1):1107-12. We studied the case of a 48-year-old woman who had resection of a pineal body tumor in terms of postoperative audiological function. Postoperative magnetic resonance imaging disclosed partial inferior colliculi destruction and medial geniculate body degeneration. A pure tone audiogram revealed only moderate sensorineural hearing loss, but her speech perception was totally impaired. The binaural sound localization function was also impaired. The auditory brain stem response (ABR) showed waves I, III, and V to have normal latencies. The amplitude of wave III was larger than that of wave V. These results support the view that the waves of the ABR are elicited from multiple sources in the auditory brain stem nuclei and tracts. This case suggests a substantial role for the inferior colliculus and medial geniculate body in the processing of speech perception and sound localization. -- Vitte E, Tankéré F, Bernat I, Zouaoui A, Lamas G, Soudant J. ENT Department, Hôpital Pitié-Salpêtrière, Paris, France. elizabeth.vitte@psl.ap-hp-hop-paris.fr Midbrain deafness with normal brainstem auditory evoked potentials. Neurology. 2002 Mar 26;58(6):970-3. The authors report two cases of patients with word deafness. The word deafness occurred after a head injury for the first patient and after an arterio venous malformation embolization for the second patient. MRI demonstrated bilateral lesions of the inferior colliculi but brainstem auditory-evoked potentials (BAEP) were within normal limits. These cases demonstrated that lesions involving the two inferior colliculi induced pure word deafness but do not affect BAEP. Comment in: Neurology. 2002 Oct 22;59(8):1293. -- Hoistad DL, Hain TC. Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, Ill. 60611-3008, USA. t-hain@northwestern.edu Central hearing loss with a bilateral inferior colliculus lesion. Audiol Neurootol. 2003 Mar-Apr;8(2):111-3. A case is presented of a 43-year-old man with bilateral lesions of the inferior colliculus (IC) due to central nervous system lymphoma. Our patient was found to have relatively normal pure-tone averages with severely reduced bilateral word recognition scores. This case illustrates that the presentation of a partial bilateral IC lesion may be of severely reduced word recognition accompanied by nearly normal pure-tone hearing. Copyright 2003 S. Karger AG, Basel -- Musiek FE, Charette L, Morse D, Baran JA. Department of Communication Sciences, Neuroraudiology Lab, University of Connecticut, Storrs, Connecticut 06269-1085, USA. frank.musiek@uconn.edu Central deafness associated with a midbrain lesion. J Am Acad Audiol. 2004 Feb;15(2):133-51; quiz 172-3. Central deafness has been linked historically to bihemispheric involvement of the temporal lobe, with more recent findings suggesting that compromise of other cortical and subcortical structures can also result in this disorder. The present investigation extends our understanding of the potential anatomical correlates to central deafness by demonstrating that bilateral involvement of an auditory structure within the midbrain can additionally result in this condition. Our subject was a 21-year-old male with a subarachnoid bleed affecting both inferior colliculi. Significant auditory deficits were noted for the middle and late auditory evoked potentials, while electrophysiologic measures of the periphery indicated normal function. The patient was enrolled in a rehabilitation program for approximately 14 weeks. Although initially unresponsive to sounds, the patient regained most of his auditory abilities during the 10 months he was followed. This case documents the range of auditory deficits that may be associated with damage to the inferior colliculi, and it profiles a hierarchical recovery of auditory function consistent with test findings. -- Kimiskidis VK, Lalaki P, Papagiannopoulos S, Tsitouridis I, Tolika T, Serasli E, Kazis D, Tsara V, Tsalighopoulos MG, Kazis A. C Department of Neurology, Aristotle University of Thessaloniki, G Papanikolaou Hospital, Greece. kimiskid@med.auth.gr Sensorineural hearing loss and word deafness caused by a mesencephalic lesion: clinicoelectrophysiologic correlations. Otol Neurotol. 2004 Mar;25(2):178-82. OBJECTIVE: To assess the role of inferior colliculi as a generator of Wave V of brainstem auditory evoked potentials and in modulating the olivocochlear efferent auditory system. STUDY DESIGN: Case review. SETTING: University and tertiary referral centers. PATIENTS: Case report of a patient with word deafness caused by mesencephalic hemorrhage according to audiologic and electrophysiologic findings. RESULTS: The patient is a 48-year-old woman who suffered word deafness caused by hemorrhage localized at the quadrigeminal plate (including the inferior colliculi). At a follow-up visit, her pure-tone audiogram revealed symmetric severe sensorineural hearing loss that had partially resolved, whereas speech audiometry showed persistent word deafness. Acoustic reflexes were elicited, with normal thresholds bilaterally. Transient evoked otoacoustic emissions were recorded from both ears, with normal response and signal-to-noise ratio, but there was a failure for their amplitude to be suppressed with contralateral sound stimulation. Brainstem auditory evoked potentials were of normal amplitude and latencies bilaterally. CONCLUSION: The finding of normal brainstem auditory evoked potentials supports the view that the neural generator of Wave V lies caudally to the inferior colliculi. Moreover, the abnormal suppression of transient evoked otoacoustic emissions indicates that descending collicular input is capable of modulating levels of excitability within the olivary nucleus and the cochlea. -- Pan CL, Kuo MF, Hsieh ST. Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan. Auditory agnosia caused by a tectal germinoma. Neurology. 2004 Dec 28;63(12):2387-9. The authors describe a patient with auditory agnosia caused by a tectal germinoma. Despite having normal audiometric tests, the patient failed to recognize words and musical characters. On head MRI, the inferior colliculi were infiltrated by tumor. Neuropsychological tests revealed severe impairment in recognition of environmental sounds and words, defective musical perception, and stop consonant-vowel discrimination. Inferior colliculus may play a role in the analysis of sound properties. Comment in: Neurology. 2005 Jul 26;65(2):339; author reply 339.