Differences between µCT-imaging and conventional CT for the diagnosis of possible diseases of the middle and inner cat ear.

The aim of this study was to check the relevance of using in-vivo micro computed tomography (µCT) for the diagnosis of possible diseases of the middle and inner ear of the cat. Therefore, on the one hand, differences of the detail detectability between the two imaging methods conventional computed tomography (cCT) and in-vivo µCT were analyzed. Six healthy cat ears were dissected and scanned several times and the obtained images were compared with each other. On the other hand, histological slices of all ears were prepared and pictures of defined anatomical structures were taken and compared with the identical sectional plane of the µCT-images. This way it was possible to evaluate the quality and clinical limitations of the in-vivo µCT. The results show that an in-vivo µCT is suitable to analyze even the smallest osseous structures, such as the semicircular ducts, the spiral osseous lamina or the ossicles whereas with the help of cCT it is not possible to identify such small osseous structures because of their blurred and less detailed representation. Delicate soft tissue structures as the membranous labyrinth including hearing and vestibular organ cannot be differentiated with as well in-vivo µCT- as with cCT-images. In-vivo µCT represent a good possibility for more detailed diagnosis of extremely fine structures which cannot be detected with cCT. Histological slices can nonetheless not be replaced by in-vivo µCT due to a too low spatial resolution and the limitations of the in-vivo µCT with regard to the evaluation of soft tissue dense structures.

Computed tomographic characteristics of pneumolabyrinth in a French bulldog with otitis media and externa.

A four-year-old female French bulldog was presented for evaluation of acute, left-sided peripheral vestibular syndrome. Computed tomographic (CT) examination of the head revealed the presence of air within the left cochlea and vestibule, consistent with pneumolabyrinth. This was concurrent with ipsilateral otitis media and externa. Pneumolabyrinth is an uncommon finding in humans and is most frequently due to head trauma and temporal bone fracture. This is the first report describing pneumolabyrinth in a dog, apparently of nontraumatic origin in this case.

Parasites in the inner ear of harbour porpoise: cases from the North and Baltic Seas.

Peribullar sinuses of harbour porpoises Phocoena phocoena are parasitized with high prevalence by the nematode Stenurus minor. The effect of S. minor on the hearing ability of this species is still undetermined. Here, we review the occurrence of S. minor in the inner ear of harbour porpoises recovered from strandings in the North and Baltic Seas. In particular, we present the results from ears collected in German and Danish waters from 2002 to 2016 and from Dutch waters from 2010 to 2016. While the prevalence of S. minor in pterygoid and peribullar sinuses and tympanic cavity was high in harbour porpoises (66.67% in our cases), its prevalence in the cochlea was rare. Only 1 case out of 129 analysed by either histology, electron microscopy or immunofluorescence showed the presence of a nematode parasite morphologically consistent with S. minor at the most basal portion of the right cochlea. This individual also had severe haemorrhage along the right cochlear spiral, which was likely caused by ectopic S. minor migration. Although this animal might have had impaired hearing in the right ear, it was otherwise in good body condition with evidence of recent feeding. These findings highlight the need to study the effect of parasites on hearing, and other pathological changes that might impair appropriate processing of acoustic information.

Vestibular syndrome associated with an ependymoma in a cat.

An ependymoma was diagnosed in a 4.5-year-old spayed Siamese cat with clinical signs of vestibular disease. Diagnosis was based on history, results of neurologic examination, and the finding of neoplastic cells in CSF. Necropsy revealed an ependymoma arising from the fourth ventricle of the ventricular CNS and involving the left medullary and cerebellar areas.

Otitis media and otitis interna. Etiology, diagnosis, and medical management.

In this article, the etiologies, clinical signs, diagnostic aids, and treatments for otitis media and interna are discussed. A review of the anatomy and physiology of the middle and inner ear structures precedes each discussion.

Surgical management of otitis media and otitis interna.

Surgical management of otitis media and otitis interna includes the following options: lateral bulla osteotomy, ventral bulla osteotomy, or curettage of the tympanic cavity. Because otitis media frequently accompanies chronic nonresponsive otitis externa, one of the above procedures may be combined with operative procedures of the external ear canal. Also, gentle selective curettage of the tympanic cavity may be combined with either lateral or ventral bulla osteotomy in the treatment of otitis media and interna. The choice of surgical procedure(s) should be based on the condition of the external ear canal (vertical and horizontal parts), the duration of clinical signs, response to previous surgery, and the familiarity of the surgeon with the different approaches and techniques. With the increased reporting of long-term results following surgical management of otitis externa, media, and interna, more meaningful conclusions concerning selection of surgical procedure may be made in the future.

Disorders of the vestibular system.

Disorders of the vestibular system are common in veterinary practice and result in a clinical syndrome characterized by head tilt, asymmetric ataxia, and nystagmus. These signs may occur with lesions involving the peripheral or central vestibular structures. Careful neurologic evaluation of the animal and knowledge of surrounding neuroanatomic structures and their functions enable the clinician to differentiate between peripheral and central disorders. Conditions resulting in peripheral vestibular symptoms include idiopathic syndromes, otitis interna, trauma, neoplasia, drug-induced ototoxicity, and congenital disorders. Radiographs of the petrous temporal bone and tympanic bulla and examination of the tympanic membrane are useful in determining the specific etiology. Central vestibular dysfunction may result from inflammatory CNS diseases, neoplasia, trauma, thiamine deficiency, and storage diseases. Cerebrospinal fluid analysis, skull radiographs, and computed tomography are diagnostic tests useful in animals with central vestibular symptoms. Once the etiology is identified, specific therapy may be provided and a more accurate prognosis can be determined.

Head tilt in horses.

Head tilt in the horse is commonly a sign of either central or peripheral vestibular disease. The confirmation of vestibular disease is based on physical findings, including results of cranial-nerve function evaluation and observation of stance, posture, and gait. Further localization is made by ancillary tests such as cerebral spinal fluid analysis, electrodiagnostic testing, and radiography. The normal anatomy and physiology of the vestibular system, the abnormal clinical signs demonstrated during physical examination, and the various etiologies are discussed.

Vacuolar degeneration of the cochlea in young rats.

In the course of investigations of the post-natal development of the ear in Sprague-Dawley rats, a hitherto unrecorded degenerative process was seen in two animals (7-and-8-days old). The process was characterized by vacuolization of almost all the cellular elements of the cochlear tissues. The overall shape and size of the cochlear structures remained well preserved. The organ of Corti did not atrophy but its components were vacuolized, as well as the cells of other inner ear tissues, except for nuclei in the lower part of the modiolus.

Abnormalities of the brainstem auditory response of the dog associated with equilibrium deficit and seizure.

The brainstem auditory evoked response (BAER) was recorded from 20 dogs, 10 exhibited vestibular deficit, and 10 presented with a history of seizures. Two dogs exhibited both types of signs. Abnormalities of the BAER, prolonged interwave latency, were seen in 8 of the 10 animals with vestibular problems, and in 7 of the 10 animals with seizure history. Several different diagnosis were associated with BAER abnormalities in both groups of animals. In 55.5% of the cases exhibiting abnormalities of the BAER, postmortem evidence of brainstem pathology was not detected. The electroencephalogram (EEG) was normal in three instances of abnormalities of the BAER. The BAER was normal in three dogs with abnormalities of the EEG. The BAER is presented as a useful diagnostic tool for brain lesions in animals with vestibular deficit and seizure history, but appears most useful when used in conjunction with the EEG. Correlations of abnormalities of the BAER and clinical course of disease are discussed.

Vestibular syndrome associated with temporohyoid joint fusion and temporal bone fracture in three horses.

Acute onset of vestibulocochlear and facial nerve dysfunction due to a stress fracture of the petrous part of the temporal bone was diagnosed in 3 horses. The fracture was secondary to chronic inflammatory changes in the petrous part of the temporal bone and the proximal stylohyoid bone, with fusion of the temporohyoid joint. Bacterial meningoencephalitis was a complicating factor. Treatment resulted in reduction of severity of clinical signs in 2 of the 3 cases, but residual compensated vestibular deficits persisted.

Panophthalmitis and otitis interna in fire-bellied toads.

Microbiologic and histologic studies were made of fire-bellied toads with signs of ocular and central nervous system disease. Providencia alcalifaciens, Citrobacter freundii, Aeromonas hydrophila, and other gram-negative bacilli were isolated from the eyes and multiple tissues of ill toads. The histologic evaluations revealed severe panophthalmitis and otitis interna.

Endolymphatic hydrops. An overview and classification.

Endolymphatic hydrops (EH) is a pathological condition which is the final common manifestation of a variety of otologic insults. In this paper we develop a classification which, on the basis of clinical and pathological data, distinguishes symptomatic and asymptomatic forms. Clinical case histories and temporal bone studies are presented to illustrate and substantiate this classification. The symptomatic form becomes evident by the hallmark symptoms of episodic vertigo and fluctuating hearing loss. The asymptomatic form is silent. Interconversion from one form to another may occur over time. Each of the forms can be subdivided, according to etiology, into embryopathic, acquired, and idiopathic types. The embryopathic type comprises those cases in which some noxious influence interferes with prenatal labyrinthine development. The acquired type includes those cases in which a documented insult, be it inflammatory or traumatic, is suffered by a previously normal labyrinth. The inflammation may be viral, bacterial, or spirochetal in nature, while the traumatic event may be either accidentally or surgically sustained. The idiopathic type includes cases in which the instigating event precipitating the EH is unknown. Menière's disease represents merely one example of the EH group of disorders, namely symptomatic idiopathic EH.

Peripheral vestibular syndrome in the dog: a review of 83 cases.

Clinical data and follow-up evaluations of 83 cases of peripheral vestibular syndrome in the dog were reviewed. The absence of physical abnormalities of the tympanic membrane and absence of radiographic changes within the tympanic bulla or petrous temporal bone were the criteria used to make the diagnosis of idiopathic benign vestibular disease. When grouped according to the cause of the syndrome, most of the dogs had been diagnosed as having either otitis media/interna (49%) or idiopathic benign vestibular disease (39%). Clinical evidence suggested that most of the cases of otitis media/interna were secondary to otitis externa.