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Head tilt and nystagmus

image of Head tilt and nystagmus
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Abstract

Head tilt and nystagmus are relatively common presentations in veterinary practice. These signs are typically associated with vestibular disease, although an intermittent head tilt alone may be due to otitis externa or other aural irritation. This chapter looks at clinical signs, lesion localization, pathophysiology, differential diagnosis, neurodiagnostic investigation, peripheral vestibular diseases, central vestibular diseases.

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/content/chapter/10.22233/9781910443125.chap11

Figures

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11.1 An 8-year-old Boston Terrier with a right-sided head tilt. (Courtesy of S Platt)
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11.2 Lesion localization for head tilt and nystagmus; the brainstem is highlighted. The peripheral section of the vestibular system originates in the petrous temporal bone and the central section resides in the brainstem and flocculonodular lobe of the cerebellum. Inset: middle and inner ear structures (magnified). The membranous labyrinth (blue) contains the sensory receptors for vestibular function and hearing. Illustration created by Allison L. Wright, MS, CMI, Athens, Georgia, USA.
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11.4 Overview of the anatomy of the middle and inner ear. Overview of the neuronal connections that form the peripheral and central vestibular systems. Stimulation of the peripheral vestibular system in the inner ear ultimately produces a conjugate deviation of the eyes to the ipsilateral side. Illustration created by Allison L. Wright, MS, CMI, Athens, Georgia, USA.
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11.6 Diagnostic algorithm for the work-up of an animal presenting with signs of peripheral vestibular disease.
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11.7 A 4-month-old Dobermann with a head tilt which the owner had identified when the dog was 2 months old. The diagnostic investigation suggested it was compatible with a congenital lesion seen in this breed. (Courtesy of S Platt)
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11.8 CT image of a cat with an aggressive tumour involving the right tympanic bulla. There is bony destruction of the bulla, extensive soft tissue involvement and evidence of extension into the cranial cavity. Contrast-enhanced transverse T1-weighted image of a dog with an aggressive tumour involving the left tympanic bulla. There is extensive soft tissue involvement and erosion of the adjacent calvarium with extension into the cranial vault.
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11.9 Open-mouth bulla view of a dog with unilateral OM/OI. The left tympanic bulla is obscured by bone and soft tissue density (arrowed) compared with the normal air-filled right bulla.
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11.10 CT image of a dog with chronic left-sided OM/OI. Note the bony sclerosis and soft tissue density within the tympanic bulla. Transverse T2-weighted MR image of a cat with OM/OI. Note that the hyperintensity seen within the bulla is present within the ventromedial and dorsolateral cavities of the middle ear.
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11.11 Contrast-enhanced CT image of a dog with OM/OI with extension into the brain. Note the soft tissue density within the tympanic bulla (arrowed). The contrast medium has enhanced areas at the cerebellopontine medullary angle on the same side (arrowheads). Contrast-enhanced transverse T1-weighted MR image of a dog with OM/OI with extension into the brain. Note the soft tissue density within the tympanic bulla (arrowed). There is evidence of linear peripheral enhancement in the caudal fossa on the same side (arrowhead).
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11.12 CT image of a cat with an inflammatory polyp in the right ear canal and secondary OM/OI. Note the soft tissue density within the tympanic bulla (black arrow) characteristic of OM/OI as well as the soft tissue density polyp obscuring the horizontal ear canal (white arrow).
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11.13 Transverse T2-weighted MR image of a cat following a traumatic head injury causing acute clinical vestibular signs and middle ear haemorrhage (arrowed).
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11.14 CT image of a dog with an intracranial intra-arachnoid cyst in the region of the quadrigeminal cistern. The cistern is represented by the sharply delineated, triangular fluid-filled space (arrowed). Note the dilated lateral ventricles on either side. Sagittal T1-weighted MR image of a dog with an intracranial intra-arachnoid cyst in the region of the quadrigeminal cistern. Note the compression of the occipital lobe of the cerebrum (arrowed) and the cerebellum (arrowhead).
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11.15 Ventroflexion of the head and neck in a cat presented with central vestibular disease due to thiamine deficiency. (Courtesy of S Platt)
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11.16 Transverse T2-weighted FLAIR MR cerebral image of a dog with confirmed thiamine deficiency. The caudal colliculi on both sides are hyperintense, compatible with cytotoxic oedema of these nuclei (arrowed). (Courtesy of L Garosi)
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11.18 Contrast-enhanced transverse T1-weighted MR image of a dog showing hyperintense lesions (arrowed) in the region of the vestibular nuclei in the medulla oblongata due to CDV infection. (Courtesy of L Garosi)
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11.19 A histopathological section of the area of the medulla affected in Figure 11.18 . The arrows indicate acidophilic intracytoplasmic CDV inclusion bodies. (H&E stain; original magnification X100) (Courtesy of M Bestbier and L Garosi)
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11.20 Pathological specimen from a cat with CNS FIP showing the marked dilatation of the lateral ventricles that is often seen with the disease secondary to obstruction of the ventricular system.
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11.21 CT image of a cat with CNS FIP showing evidence of dilated lateral ventricles. Contrast-enhanced transverse T1-weighted MR image of a cat with CNS FIP showing evidence of dilatation of the fourth ventricle and periventricular contrast enhancement (arrowed).
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11.22 Sagittal T2-weighted cerebral MR image of a cat that presented with vestibular disease due to CNS toxoplasmosis. Arrows indicate a diffuse area of hyperintensity associated with infection within the brainstem, extending caudally to the area of the vestibular nuclei. (Courtesy of S Platt)
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11.23 Impression smear from a cat with cryptococcosis showing the presence of several encapsulated cryptococcal organisms (arrowed). (Diff-Quik; original magnification X500)
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11.25 CT image of a Yorkshire Terrier diagnosed with necrotizing encephalomyelitis showing a focal area of hypoattenuation in the right forebrain (arrowed).
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11.26 Transverse T2-weighted cerebral MR image of a Maltese dog with necrotizing encephalitis showing diffuse asymmetrical hyperintensity throughout the frontal lobe parenchyma. (Courtesy of S Platt)

Supplements

Myringotomy

A myringotomy procedure is demonstrated in this clip. With the dog under general anaesthesia and in lateral recumbency, an otoscope (or video endoscope) is used to guide a sterile needle through the tympanum, after which sterile saline is gently flushed into the middle ear before it is aspirated for culture and sensitivity testing. (See page 198 in the Manual)

Positional nystagmus

A cat showing the onset of vertical nystagmus when turned on to its back. This condition is termed positional nystagmus. (See page 195 in the Manual)

Positional strabismus

A dog exhibiting a right-sided positional strabismus suggestive of ipsilateral vestibular disease. As the head is moved a variable positional nystagmus is seen, which has a fast phase to the left when horizontal, compatible with right-sided disease. (See page 195 in the Manual)

Spontaneous nystagmus (1)

A Boston Terrier with a mild left-sided head tilt exhibiting a spontaneous nystagmus with the fast phase to the right. (See page 195 in the Manual)

Spontaneous nystagmus (2)

A dog with spontaneous nystagmus in a predominately horizontal field. Note that this varies and can become intermittently vertical. (See page 195 in the Manual)

Vestibular disease

A cat with vestibular disease exhibiting a profoundly vestibular ataxic gait and circling. A head tilt can also be seen in this cat. (See page 195 in the Manual)

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