Intracranial inflammatory polyp with cerebellopontine compression and leptomeningitis secondary to chronic otitis in a red kangaroo

CNS lesions associated with chronic otitis have not been reported in red kangaroos (Macropus rufus), to our knowledge. Here we describe an intracranial inflammatory polyp secondary to chronic otitis in a 6-y-old female red kangaroo with right auricular discharge, loss of balance, and head tilt. Autopsy highlighted a pale-yellow, firm, intracranial polypoid growth that extended from the right tympanic cavity through the internal acoustic meatus and intracranially, with compression of the right cerebellopontine angle. Anaerobic bacterial culture yielded Bacteroides pyogenes from fresh brain and a right external ear swab. Histologically, the tympanic cavity was effaced by neutrophils and macrophages surrounded by lymphocytes and plasma cells, as well as edematous fibrovascular tissue. The epithelial lining of the mucoperiosteum was hyperplastic, with epithelial pseudoglands surrounded by fibrovascular tissue. Areas of temporal bone lysis and remodeling were associated with the inflammatory changes, which occasionally surrounded adjacent nerves. Fibrovascular tissue and inflammatory cells extended from the tympanic cavity through the internal acoustic meatus and into the intracranial cavity, forming the polypoid growth observed grossly; the polyp consisted of a dense core of fibrovascular tissue with scattered clusters of neutrophils and foamy macrophages. Lymphocytes and plasma cells surrounded the leptomeningeal perivascular spaces in the brainstem, cerebellum, and occipital lobe.

Clinical presentation, treatment, and outcome of 24 dogs with bacterial meningitis or meningoencephalitis without empyema (2010-2020)

BACKGROUND

Bacterial meningitis (BM) and meningoencephalitis (BMEM) are associated with high case fatality rates and neurologic sequelae in people, but limited data exists on outcome in dogs.

HYPOTHESIS/OBJECTIVES

To report the clinicopathologic features, treatment and outcome of BM/BMEM in dogs, with a focus on clinical presentation, relapse and long-term neurological deficits.

ANIMALS

Twenty-four client-owned dogs diagnosed with BM/BMEM without empyema.

METHODS

Retrospective case series of dogs diagnosed with BM/BMEM from 5 veterinary referral hospitals between January 2010 and August 2020.

RESULTS

Twenty-four dogs were included. Median duration of clinical signs was 2 days (range ≤24 hours to 30 days) and signs recorded included pyrexia (3) and cervical hyperesthesia (10). Neurological deficits were present in 18 dogs including altered mentation (12), ataxia (8), nonambulatory status (8), head tilt (8), and cranial nerve deficits (13). Intracellular bacteria were visualized on cerebrospinal fluid (CSF) analysis in 15/24 dogs, with positive CSF bacteriological culture in 8/21. Otitis media/interna (OMI) was diagnosed in 15/24 dogs, of which 6/15 dogs underwent total ear canal ablation and lateral bulla osteotomy. Twenty dogs survived to hospital discharge. Median duration of antibiotic administrations was 8 weeks (range, 2-16 weeks). Glucocorticoids were administered to 15 dogs. Median follow-up time was 92 days (range, 10-2233 days). Residual neurological deficits were reported in 9 dogs, with a single case of suspected relapse.

CONCLUSIONS AND CLINICAL IMPORTANCE

Clinical signs were variable in dogs with BM/BMEM, the nidus of bacterial infection was often OMI and the majority of dogs made a full recovery with treatment.

Clinical Presentation, MRI Characteristics, and Outcome of Conservative or Surgical Management of Spinal Epidural Empyema in 30 Dogs

Spinal epidural empyema (SEE) represents a neurological emergency in veterinary medicine, but information on this condition is limited to date. This retrospective case series study describes the clinical and magnetic resonance imaging (MRI) features, and the outcome of conservative or surgical management of SEE in 30 dogs diagnosed with SEE from September 2015 to March 2020 at one referral neurology centre. The most frequent clinical sign was pain 28/30 (93%), and 22/30 (73%) showed neurological signs with ambulatory paraparesis/tetraparesis 15/30 (50%), monoparesis 1/30 (3.3%), non-ambulatory paraparesis 3/30 (10%), or paraplegia 3/30 (10%). MRI was valuable for the diagnosis and in the follow-up. In this group of dogs, 24/30 (80%) were conservatively treated and 6/30 (20%) were surgically treated. The outcome was considered favourable in all dogs: 20/30 (66.6%) achieved full recovery (3 surgically treated and 17 medically treated) and 10/30 (33.3%) dogs had an improvement in the neurological signs with residual ambulatory paresis (3 surgically treated and 7 medically treated). Surgical treatment showed better short-term (7 days) outcomes than medical treatment in non-ambulatory paraparetic or paraplegic dogs (33%). Nevertheless, this study suggests that a good recovery may be achieved with conservative treatment even for non-ambulatory or paraplegic dogs. Further prospective studies, with a standardised protocol of diagnostic tests and a homogeneous distribution of conservatively and surgically treated dogs, are needed to establish treatment guidelines.

Otitis media and interna with or without polyps in cats: association between meningeal enhancement on postcontrast MRI, cerebrospinal fluid abnormalities, and clinician treatment choice and outcome

OBJECTIVES

The aim of this study was to evaluate the association between meningeal enhancement (MgE) and cerebrospinal fluid (CSF) analysis results, their individual association with bacteriology results from affected ear samples and whether these test results influenced clinicians' therapeutic choice in cats with otitis media and interna (OMI).

METHODS

This was a multicentre retrospective study carried out over an 8-year period. Cats diagnosed with OMI, with or without a nasopharyngeal polyp, leading to peripheral vestibular signs were included. Only cats for which MRI with postcontrast T1-weighted sequences and CSF analyses available were included. Cats with intra-axial MRI lesions or empyema were excluded.

RESULTS

Fifty-eight cats met the inclusion criteria. MgE was reported in 26/58 cases, of which nine had an abnormal CSF result (increased total nucleated cell count [TNCC] or total protein); 32/58 cases had no MgE, of which 10 showed abnormal CSF results. There was no association between bacteriology results (external ear canal or bulla) and MgE or abnormal CSF results. CSF abnormalities were statistically significantly more common in acute cases (n = 16/37) than in chronic cases (n = 3/21; Fischer's test P = 0.04). Prednisolone was prescribed in 10/16 cases with increased TNCC. Among the 42 cases with normal TNCC, 15 received prednisolone and 13 received non-steroidal anti-inflammatory drugs. Various antimicrobial drugs were prescribed in 53/58 cats. Duration of antimicrobial treatment was similar, regardless of positive bacterial culture (5.58 vs 4.22 weeks), abnormal CSF (5.83 vs 4.76 weeks) or MgE (5.33 vs 4.90 weeks).

CONCLUSIONS AND RELEVANCE

No association was found between the CSF and MgE results. Furthermore, no association was found between MgE, CSF or bacteriology findings. In addition, abnormal CSF results might lead the clinician to treat with corticosteroids, but they did not have any impact on duration of antimicrobial treatment. CSF abnormalities were seen significantly less frequently in chronic cases. The outcome tended to be poorer when MgE was detected on MRI.

Inflammatory Disease Affecting the Central Nervous System in Dogs: A Retrospective Study in England (2010–2019)

The epidemiology of inflammatory diseases affecting the central nervous system (CNS) in dogs is largely unknown. We aimed to report the relative proportion of different causes of inflammatory disease affecting the CNS in dogs and identify predictors for infectious vs. immune-mediated conditions and predictors for the most common diseases affecting the brain and the spinal cord. This was a retrospective cohort study over a 10-year period in 2 referral institutions using multivariable and multinomial logistic regression for identification of risk factors. In total, 1,140 client-owned dogs diagnosed with inflammatory disease affecting the CNS were included. Fifteen different diagnoses were identified, with immune-mediated (83.6%) disease being more common than infectious conditions (16.4%). The most common immune-mediated conditions diagnosed were meningoencephalitis of unknown origin (47.5%) and steroid-responsive meningitis–arteritis (30.7%), and the most common infectious conditions were discospondylitis (9.3%) and otogenic intracranial infection (2.2%). Older age (p < 0.001, OR = 1.019, 95% CI: 1.014–1.024), higher body weight (p < 0.001, OR = 1.049, 95% CI: 1.025–1.074), male sex (p = 0.009, OR = 1.685, 95% CI: 1.141–2.488), longer duration of the clinical signs before presentation (p < 0.001, OR = 1.011, 95% CI: 1.006–1.017), progressive nature of the clinical signs (p < 0.001, OR = 2.295, 95% CI: 1.463–3.599), identification of a possibly associated preceding event (p = 0.0012, OR = 1.93, 95% CI: 1.159–3.213), and hyperesthesia on presentation (p < 0.001, OR = 2.303, 95% CI: 1.528–3.473) were associated with a diagnosis of infectious diseases. Our data shows that immune-mediated diseases are more common than infectious conditions as a cause for inflammatory CNS disease in dogs. The risk factors for the most common diagnoses were identified from signalment, history, and findings of the physical and neurological examinations to give valuable information that can guide clinicians with their investigations.

Dogs and cats with presumed or confirmed intracranial abscessation have low apparent diffusion coefficient values

Intracranial abscessation is a life-threatening condition in dogs and cats, and rapid diagnosis is important for prognosis and treatment planning. The aims of this retrospective, single-center, case series study were to describe clinical and MRI diffusion-weighted imaging characteristics in three dogs and three cats with presumed or confirmed intracranial abscessation. All lesions appeared hyperintense on b1000 trace diffusion-weighted images, hypointense on apparent diffusion coefficient (ADC) map, with mean ADC values ranging from 0.37 to 1.24 × 10^-3  mm² /s. The majority (5/6) of the obtained mean ADC values were low (<1.10 × 10^-3  mm² /s), as previously reported in the human literature.

Clinical reasoning in feline vestibular syndrome: which presenting features are the most important?

OBJECTIVES

The aim of this study was to evaluate whether clinical variables from the history, clinical presentation, and physical and neurological examinations of cats with vestibular syndrome were statistically predictive of the underlying diagnosis.

METHODS

In total, 174 cats presenting with vestibular syndrome between January 2010 and May 2019 were investigated. Univariate statistical analysis of clinical variables was performed and those statistically associated with a diagnosis were retained for multivariable binary logistic regression modelling.

RESULTS

The seven most prevalent diagnoses represented 95% of vestibular presentations, which included: otitis media/interna (n = 48), idiopathic vestibular syndrome (n = 39), intracranial neoplasia (n = 24), middle ear polyp (n = 17), feline infectious peritonitis (n = 13), thiamine deficiency (n = 13) and intracranial empyema (n = 11). Idiopathic vestibular syndrome was commonly associated with non-purebred cats and had 17.8 times the odds of an improving clinical progression (95% confidence interval [CI] 1.3-250.0; P = 0.03). Intracranial neoplasia was associated with older age and chronic onset of clinical signs, and was significantly more likely to have a central vestibular neuroanatomical localisation (95% CI 8.5-344,349,142.0; P = 0.015) with postural deficits on neurological examination. Thiamine deficiency was more common in female cats, with 52.6 times the odds of a waxing and waning clinical progression (95% CI 1.2-1000; P = 0.038) and 6.8 times the odds of presenting with bilateral vestibular signs (95% CI 1.0-45.7; P = 0.047) and wide excursions of the head (95% CI 1.0-45.7; P = 0.047). Middle ear polyps were associated with 8.8 times the odds of presenting with Horner syndrome (95% CI 1.5-50.0; P = 0.015).

CONCLUSIONS AND RELEVANCE

Although it may be difficult to identify the underlying diagnosis in cats with vestibular syndrome from the presenting features alone, there are instances in which discrete clinical features may help to guide clinical reasoning when evaluating cats with vestibular presentations.

Cerebrospinal fluid analysis lacks diagnostic specificity in dogs with vestibular disease

BACKGROUND

Although, vestibular syndrome is a common neurological presentation, little is known about the diagnostic value of cerebrospinal fluid (CSF) analysis in vestibular syndrome in dogs.

METHODS

Medical records were retrospectively reviewed, and dogs with vestibular disease that had undergone magnetic resonance imaging of the head, CSF analysis and were diagnosed with central or peripheral vestibular syndrome were included. Disorders affecting the central vestibular system included meningoencephalitis of unknown origin (MUO), brain neoplasia, ischaemic infarct, intracranial empyema or metronidazole toxicity. Disorders affecting the peripheral vestibular system included idiopathic vestibular disease, otitis media/interna or neoplasia affecting the inner ear structures. Total nucleated cell concentration (TNCC), total protein concentration (TP) and cytologic assessment were recorded.

RESULTS

A total of 102 dogs met the inclusion criteria. The sensitivity and specificity of increased CSF TNCC to differentiate central from peripheral vestibular syndrome was 49% and 90%, while the sensitivity and specificity of increased TP was 58% and 39%, respectively. The TNCC and TP in dogs with MUO were significantly higher than in dogs with idiopathic vestibular disease (p = 0.000 and p = 0.004). MUO was associated with lymphocytic pleocytosis, while idiopathic vestibular disease and ischaemic infarct were associated with the presence of activated macrophages or normal cytology (p = 0.000).

CONCLUSION

Although consistent CSF abnormalities were observed in dogs with MUO, CSF analysis did not allow reliable differentiation between central and peripheral vestibular syndrome. CSF analysis is not reliable as the sole diagnostic technique in dogs with vestibular disease.

Clinical reasoning in canine vestibular syndrome: Which presenting factors are important?

BACKGROUND

Although the use of clinical reasoning has been evaluated for several neurological presentations, this approach has not yet been investigated for dogs with vestibular syndrome.

METHODS

Two hundred and thirty-nine dogs presenting with vestibular syndrome were included in this retrospective study. Univariate analysis of variables (clinical history, signalment, clinical presentation and neurological examination findings) was performed. Variables with p < 0.3 were selected for logistic regression.

RESULTS

Ninety-five percent of dogs were represented by eight conditions: idiopathic vestibular disease (n = 78 dogs), otitis media interna (n = 54), meningoencephalitis of unknown origin (n = 35), brain neoplasia (n = 26), ischaemic infarct (n = 25), intracranial empyema (n = 4), metronidazole toxicity (n = 3) and neoplasia affecting the middle ear (n = 3). Idiopathic vestibular disease was associated with higher age, higher bodyweight, improving clinical signs, pathological nystagmus, facial nerve paresis, absence of Horner's syndrome and a peripheral localisation. Otitis media interna was associated with younger age, male gender, Horner's syndrome, a peripheral localisation and a history of otitis externa. Ischaemic infarct was associated with older age, peracute onset of signs, absence of strabismus and a central localisation.

CONCLUSIONS

Discrete clinical features can be used to identify the most likely diagnosis in dogs with vestibular syndrome.

Comparison of the effects of 7.2% hypertonic saline and 20% mannitol on electrolyte and acid-base variables in dogs with suspected intracranial hypertension

Background

Hyperosmolar agents frequently are used to decrease intracranial pressure but their effects on electrolyte and acid‐base variables have not been prospectively investigated.

Objectives

Compare duration and magnitude of changes in electrolyte and acid‐base variables after hyperosmolar treatment.

Animals

Twenty‐eight client‐owned dogs with intracranial hypertension caused by various pathologies.

Methods

Prospective, randomized, nonblinded, experimental cohort study. Fifteen dogs received a single dose (4 mL/kg) of 7.2% hypertonic saline (HTS), 13 dogs received 20% mannitol (MAN) 1 g/kg IV. Electrolyte and acid‐base variables were measured before (T₀), and 5 (T₅), 60 (T₆₀), and 120 (T₁₂₀) minutes after administration. Variables were compared between treatments and among time points within treatment groups.

Results

Mean plasma sodium and chloride concentrations were higher after HTS than MAN at T₅ (158 vs 141 mEq/L; 126 vs 109 mEq/L) and significant differences were maintained at all time points. After HTS, plasma sodium and chloride concentrations remained increased from T₀ at all time points. After MAN, plasma sodium and chloride concentrations decreased at T₅, but these changes were not maintained at T₆₀ and T₁₂₀. Plasma potassium concentration was lower at T₅ after HTS compared with T₀ (3.6 vs 3.9 mEq/L) and compared to MAN (3.6 vs 4.1 mEq/L). At T₆₀ and T₁₂₀, plasma ionized calcium concentration was lower after HTS than MAN (1.2 vs 1.3 mmol/L). No significant differences were found in acid‐base variables between treatments.

Conclusions and Clinical Importance

At the administered dose, dogs receiving HTS showed sustained increases in plasma sodium and chloride concentrations, whereas dogs receiving MAN showed transient decreases. Future studies should assess the effects of multiple doses of hyperosmolar agents on electrolyte and acid‐base variables.

CT-guided drainage of a brainstem abscess in a cat as an emergency treatment procedure

Case summary

A 3-year-old male neutered domestic shorthair cat was presented with a 1-week progressive and rapidly deteriorating history of lethargy and abnormal behaviour. Neurolocalisation indicated multifocal intracranial lesions (right oculomotor nerve, brainstem [obtundation, non-ambulatory tetraparesis, vestibular dysfunction and intermittent decerebrate rigidity] and possibly the thalamus [left-sided pleurothotonus]), or more likely a single brainstem lesion with mass effect. MRI of the brain demonstrated a brainstem abscess causing severe dorsal displacement particularly affecting the pons and the medulla oblongata causing cerebellar vermis herniation through the foramen magnum. CT-guided free-hand technique drainage of the brain abscess was performed and broad spectrum antibiotics were started based on sensitivity results. The cat recovered uneventfully from anaesthesia displaying marked improvement immediately after the procedure. Antibiotics were continued for 8 months; repeat imaging prior to withdrawal found complete resolution of the brainstem abscess.

Relevance and novel information

Free-hand CT-guided drainage of a brainstem abscess is not without risk; however, in this case it led to significant clinical improvement and stabilisation likely owing to reduced intracranial pressure. It also provided a diagnostic sample that allowed successful medical treatment planning and outcome. To our knowledge, this is the first report describing the successful management of a brainstem abscess by CT-guided drainage in the veterinary literature. It suggests that stereotactic drainage followed by medical therapy can be considered a successful therapeutic alternative to brain surgery or medical treatment alone, providing an emergency treatment in cases of acute brainstem dysfunction.

Glioma Mimics: Magnetic Resonance Imaging Characteristics of Granulomas in Dogs

Granulomas can "mimic" gliomas on magnetic resonance imaging (MRI) in human patients. The goal of this retrospective study was to report canine brain granulomas that were consistent with glioma based upon MRI, report their histologic diagnosis, and identify MRI criteria that might be useful to distinguish granuloma from glioma. Ten granulomas, initially suspected to be glioma based on MRI, were ultimately diagnosed as granulomatous meningoencephalomyelitis (n = 5), infectious granulomas (n = 3) or other meningoencephalitis (n = 2). Age was 1.6-15.0 years and two dogs were brachycephalic breeds. MRI characteristics overlapping with glioma included intra-axial, heterogeneous, T2-weighted hyperintense, T1-weighted hypointense to isointense mass lesions with contrast-enhancement. Signals on fluid attenuation inversion recovery, gradient echo and diffusion weighted imaging also matched glioma. Peri-lesional edema and mass effect were toward the high end of findings reported for glioma. MRI characteristics that would be considered unusual for glioma included dural contact (n = 4), T2-hypointensity (n = 2), concomitant meningeal-enhancement (n = 9), and minor changes in the contralateral brain (n = 2). Cerebrospinal fluid analysis revealed albuminocytological dissociation or mild pleocytosis. These cases show that granulomas can "mimic" glioma on canine brain MRI. In individual cases, certain MRI findings may help increase the index of suspicion for granuloma. Lack of pronounced cerebrospinal fluid pleocytosis does not exclude granuloma. Signalment is very useful in the suspicion of glioma, and many of these dogs with granuloma were of ages and breeds in which glioma is less commonly seen.

Retrospective evaluation of the clinical presentation, magnetic resonance imaging findings, and outcome of dogs diagnosed with intracranial empyema (2008-2015): 9 cases

OBJECTIVE

To describe the clinical presentation, advanced imaging findings, and short- and long-term outcomes in dogs with intracranial empyema.

DESIGN

Retrospective case series.

ANIMALS

Client-owned dogs diagnosed with intracranial empyema.

METHODS

Medical records from 2 referral hospitals were searched for dogs diagnosed with intracranial empyema. To be included in this study, dogs had to fulfill 1 or more of the following 3 inclusion criteria: a magnetic resonance imaging (MRI) scan with space occupying accumulation of extra-axial material suggestive of empyema, a cerebrospinal fluid analysis suggestive of empyema, or direct visualization of purulent material during intracranial surgery.

RESULTS

Nine dogs with intracranial empyema were included, with a median age of 3.5 years (range: 4 mo-12.5 y). All presented as emergencies with 7 of the 9 dogs showing neurological abnormalities and 2 of the 9 with retrobulbar swelling and exophthalmos. Six had surgical intervention, 1 was medically managed, and the remaining 2 dogs were euthanized. Typical MRI findings included extra-axial, T1-weighted hypo- to isointense, T2-weighted hyperintense material compared to gray matter with varying degrees of contrast enhancement, with 6 of 8 showing evidence of contiguous infection from adjacent structures on MRI. For 7 dogs, ≥1 samples were sent for culture and sensitivity, with Enterococcus (surgical swab), Streptococcus pneumonia (from cerebral spinal fluid), and coagulase positive Staphylococcus (ear swab) being cultured. The median antimicrobial course length was 6 weeks (range: 2-28 wk). All dogs for which treatment was attempted survived to discharge, with a median hospitalization time of 7 days (range: 4-10 d). Four of the 7 are still alive at the time of writing (1 lost to follow-up; 2 euthanized for other reasons) with all 4 considered neurologically normal with a successful long-term outcome.

CONCLUSION

Although intracranial empyema in dogs is a rare condition, excellent outcomes are possible in those cases treated appropriately.

Comparison of medical and/or surgical management of 23 cats with intracranial empyema or abscessation

OBJECTIVES

Feline intracranial abscessation or empyema is infrequently reported in the veterinary literature. To date, the largest study is based on a population of 19 cats with otogenic infection. The aim of this study was to review a larger population of cats with intracranial empyema from multiple aetiologies and document their signalment, imaging findings, treatment protocols (including medical and/or surgical management) and to compare outcomes.

METHODS

Cases presenting to a single referral centre over a 10 year period with compatible history, neurological signs and imaging findings consistent with intracranial abscessation and empyema were reviewed retrospectively.

RESULTS

Twenty-three cats met the inclusion criteria. Advanced imaging (CT and/or MRI) was performed in 22/23 cats; one case was diagnosed via ultrasound. Ten cases underwent medical and surgical management combined, 10 underwent solely medical management and three were euthanased at the time of diagnosis. Short-term outcome showed that 90% of surgically managed and 80% of medically managed cats were alive at 48 h post-diagnosis. Long-term survival showed that surgically managed cases and medically managed cases had a median survival time of 730 days (range 1-3802 days) and 183 days (range 1-1216 days), respectively. No statistical significance in short- or long-term survival ( P >0.05) was found between medically and surgically managed groups.

CONCLUSIONS AND RELEVANCE

Feline intracranial abscessation and empyema are uncommon conditions that have historically been treated with combined surgical and medical management. This study documents that, in some cases, intracranial abscessation and empyema can also be successfully treated with medical management alone.

Clinical features and short-term outcome of presumptive intracranial complications associated with otitis media/interna: a multi-center retrospective study of 19 cats (2009-2017)

OBJECTIVES

The aim of this study was to compile an overview of the clinical features of intracranial complication of otitis media/interna (OMI) in cats managed across five veterinary referral hospitals. Of additional interest were culture results that could inform empirical antibiotic selection, as well as outcome with both medical and surgical management.

METHODS

A retrospective medical record review was conducted at five veterinary referral practices to identify cats with a diagnosis of intracranial complication secondary to OMI between 2009 and 2017. Clinical features, diagnostic findings, treatment and outcome were recorded.

RESULTS

At total of 19 cats were identified. Sixty-three percent had no previous history of ear infection. Otoscopic examination was normal in 47% of cases. The most common bacterial isolate was Pasteurella multocida, which was identified in 24% of cases. Outcome was successful for 83% of cats managed with ventral bulla osteotomy (VBO) and in 66% of cats managed without surgical intervention.

CONCLUSIONS AND RELEVANCE

Clinical suspicion of intracranial complications of OMI should remain high in cats with central vestibular disease even if otoscopic examination is normal. Antibiotic selection should be based on a culture and sensitivity; however, initial antibiotic therapy should include broad-spectrum coverage with special consideration for P multocida. Cats with intracranial complications of OMI can have a good outcome with either surgical or medical management and prospective studies are needed to assess the role of VBO in enhancing recovery.

Clinical analysis and nonsurgical management of 11 dogs with aural cholesteatoma

BACKGROUND

Aural cholesteatomas, also called tympanokeratomas, are destructive and expansile growths of keratinizing epithelium that develop in the middle ear. They have been reported sporadically in dogs, and surgery is usually the recommended treatment.

OBJECTIVES

To describe the common clinical, radiological and histological findings of cholesteatoma; to report on the outcome of conservative management.

ANIMALS

Eleven dogs (13 ears) with cholesteatomas.

METHODS AND MATERIALS

Medical records were reviewed for dogs diagnosed with cholesteatoma between 2012 and 2018. All dogs had computed tomography (CT) and/or magnetic resonance imaging (MRI) followed by trans-canal endoscopic procedure (TEP) for removal and biopsy of middle ear lesions. Dogs were then treated with in-clinic flushing initially weekly tapered to monthly, as well as at-home ear cleaning and application of topical otic steroid medication, initially daily then tapered to once or twice weekly.

RESULTS

Nine dogs had a history of chronic otitis externa; head tilt or facial paralysis was present in seven and four cases, respectively. Otic examination identified a protruding nodule in seven ears. CT demonstrated soft tissue-like material in 12 bullae and expansion in seven bullae. MRI revealed minimally contrast-enhancing bulla contents in 12 ears. Post-TEP and with maintenance medical treatment, nine ears had no further signs of middle ear disease during a mean follow-up of 27.9 months.

CONCLUSIONS AND CLINICAL IMPORTANCE

The results suggest that otitis externa may not necessarily precede cholesteatoma in all dogs. MRI appears to be more sensitive than CT for identifying cholesteatomas. Conservative treatment of cholesteatomas could be useful before or as an alternative to surgery.

Bilateral tympanokeratomas (cholesteatomas) with bilateral otitis media, unilateral otitis interna and acoustic neuritis in a dog

Background

An aural cholesteatoma, more appropriately named tympanokeratoma, is an epidermoid cyst of the middle ear described in several species, including dogs, humans and Mongolian gerbils. The cyst lining consists of stratified, keratinizing squamous epithelium with central accumulation of a keratin debris. This case report describes vestibular ganglioneuritis and perineuritis in a dog with chronic otitis, bilateral tympanokeratomas and presumed extension of otic infection to the central nervous system.

Case presentation

An 11-year-old intact male Dalmatian dog with chronic bilateral otitis externa and sudden development of symptoms of vestibular disease was examined. Due to the dog’s old age the owner opted for euthanasia without any further examination or treatment and the dog was submitted for necropsy. Transection of the ears revealed grey soft material in the external ear canals and pearly white, dry material consistent with keratin in the tympanic bullae bilaterally. The brain and meninges were grossly unremarkable. Microscopical findings included bilateral otitis externa and media, unilateral otitis interna, ganglioneuritis and perineuritis of the spiral ganglion of the vestibulocochlear nerve and multifocal to coalescing, purulent meningitis. A keratinizing squamous epithelial layer continuous with the external acoustic meatus lined the middle ear compartments, consistent with bilateral tympanokeratomas. Focal bony erosion of the petrous portion of the temporal bone and squamous epithelium and Gram-positive bacterial cocci were evident in the left cochlea. The findings suggest that meningitis developed secondary to erosion of the temporal bone and ganglioneuritis and/or perineuritis of the vestibulocochlear nerve.

Conclusions

Middle ear tympanokeratoma is an important and potentially life-threatening otic condition in the dog. Once a tympanokeratoma has developed expansion of the cyst can lead to erosion of bone and extension of otic infection to the inner ear, vestibulocochlear ganglion and nerve potentially leading to bacterial infection of the central nervous system.

Electronic supplementary material

The online version of this article (10.1186/s13028-018-0386-4) contains supplementary material, which is available to authorized users.

Cerebral Ventriculitis Associated with Otogenic Meningoencephalitis in a Dog

A dog was evaluated for rapidly progressive mentation change, ataxia, and tetraparesis. The dog's neurological status deteriorated drastically. It became comatose with bilateral mydriasis, and the pupillary light reflex was absent. An anti-inflammatory dose of methylprednisolone was administered, and temporary stabilization of neurological status was achieved. MRI findings were suggestive of ventriculitis and meningoencephalitis originating from the left tympanic cavity. A gadolinium leakage phenomenon was noted, likely resulting from severe damage to the blood-cerebrospinal fluid barrier during the inflammatory process. Analysis of the cerebrospinal fluid and materials in the left tympanic cavity further confirmed the diagnosis. Following surgical and antibiotic treatment, the dog recovered well with only a mild residual head tilt. Seven months after surgery, the dog had a recurrent infection of the left tympanic cavity without intracranial involvement. A second surgery led to an uneventful recovery, and the dog was clinically normal except for a mild head tilt 3 yr after the initial presentation. This is the first report describing ventriculitis associated with otogenic meningoencephalitis in dogs and a gadolinium leakage phenomenon displayed on MRI. The long-term outcome of ventriculitis-complicated otogenic meningoencephalitis in dogs could be satisfied with prompt diagnosis and treatment.

Otogenic meningoencephalomyelitis due toCryptococcus gattii(VGII) infection in a cat from Western Australia

Case summary

A 7-year-old spayed domestic longhair cat from Perth, Western Australia, presented with left-sided head tilt, dysphonia, head shaking, inappetence and weight loss. A polypoid lesion had previously been removed from the external ear canal. Otitis media with extension into the external ear canal was suspected and investigated using video-otoscopy and computed tomography examination. Invasive disease with extension from the middle ear to the base of the skull, and intracranial extension into the caudal fossa and cranial cervical vertebral canal was detected. Cytology of external ear canal exudate showed capsulated budding yeasts and Cryptococcus gattii VGII was cultured. Treatment with amphotericin B infusions and oral fluconazole was prescribed, with nutritional support via oesophagostomy tube. The cat clinically recovered 12 months after treatment commenced.

Relevance and novel information

This case report describes the successful medical treatment of otogenic meningoencephalomyelitis due to C gattii (VGII) infection in a cat.

Cholesteatoma and meningoencephalitis in a dog with chronic otitis externa

A 10-year-old female spayed German Shepherd dog, with a year-long history of recurrent left ear infections, was presented for progressive ataxia, head tilt, and pain on opening of the mouth. On physical examination, a large amount of ceruminous debris was present in the left ear and multiple neurologic defects localizing to the cerebellum and vestibular system were identified. Magnetic resonance imaging (MRI) demonstrated a minimally contrast-enhancing mass within the left bulla, an intracranial space-occupying, heterogeneously contrast-enhancing lesion at the level of the left cerebello-medullary junction, and contrast enhancement of the ipsilateral meninges. Cerebrospinal fluid analysis revealed a marked mixed cell pleocytosis (nucleated cell count 655 cells/μL). The mass was visualized within the horizontal ear canal by otoscopic examination and a biopsy was taken. Impression smears of the biopsy contained many anucleate keratinized squamous epithelial cells, mild mixed inflammation, and few presumptive fibroblasts. With the provided clinical history and MRI findings, a cytologic diagnosis of cholesteatoma was made. A ventral bulla osteotomy was performed, and histopathologic examination of resected tissue confirmed the cytologic diagnosis of cholesteatoma. The dog's clinical symptoms improved postoperatively, but the dog died of unrelated causes, 3.5 months later. To our knowledge, this is the first description of the cytologic features of a cholesteatoma, which is a nonneoplastic, but locally invasive epidermoid cyst, in the middle ear of dogs.

Atypical, abscessated nasopharyngeal polyp associated with expansion and lysis of the tympanic bulla

A 5-year-old, male neutered domestic shorthair cat was referred for investigation of lethargy, weight loss, pyrexia and upper respiratory tract signs. On computed tomography, an expansile, osteodestructive lesion in the right tympanic bulla was identified. A soft tissue mass extended from the bulla into the nasopharynx, cranium and subcutaneous tissues. The nasopharyngeal mass ruptured during handling, liberating purulent material from which Pasteurella multocida was isolated in pure culture. The lesion was most likely an atypical, abscessated nasopharyngeal polyp. The cat was treated with bulla osteotomy and antibiotics, and made a complete recovery.

MRI findings of a middle ear cholesteatoma in a dog

This article describes the MRI features of a middle ear cholesteatoma in an 8 yr old flat-coated retriever. Physical examination revealed pain on opening the jaw, and otoscopic examination showed tympanic membrane rupture associated with hyperplastic tissue at the entrance of the middle ear. Standard MRI sequences allowed for the identification of a severely expanded bulla containing material that was isointense to brain tissue on T1-weighted images and of mixed intensity on T2-weighted and fluid-attenuated inversion recovery sequences. No postcontrast enhancement of the content was present, but the lining of the bulla was partially enhanced. The images allowed evaluation of the surgical margins and the secondary changes due to the expansion of the mass. Surgery was performed and histopathology confirmed the presumptive diagnosis of cholesteatoma. In the present case, MRI appeared to serve as a good alternative to computed tomography for the diagnosis of cholesteatoma.

Advanced imaging: use and misuse

SUMMARY

The primary purpose of diagnostic imaging is to enable clinicians to make correct decisions about a patient's diagnosis and severity of its condition and, thereby, to contribute to effective and efficient treatment. Advanced imaging modalities are inherently better detectors of morphological lesions than radiography; hence, they offer the possibility of more accurate diagnosis and staging, with correspondingly better patient outcomes. However, there is a lack of evidence that better outcomes are being realised for veterinary patients. Furthermore, increased use of advanced imaging carries the possibility of increased misuse, primarily through unnecessary studies that contribute little to patient management other than increased costs.

SCOPE

This article is intended to be relevant to all veterinary species. Advanced imaging of cats is not sufficiently developed as a specific discipline that a balanced review could be based purely on feline examples or references.

Cholesteatoma after lateral bulla osteotomy in two brachycephalic dogs

This report describes a French bulldog and a pug that presented to the authors' hospital following total ear canal ablation (TECA) and lateral bulla osteotomy (LBO), with signs of recurring otitis media and difficulty opening their mouths. The bulldog also had unilateral facial paralysis and sensory deficits of the trigeminal nerve on the ipsilateral side. Computed tomography and MRI scans suggested cholesteatoma in the bulldog, but showed only slight enlargement of the bulla in the pug. Histopathologic examination of samples yielded cholesteatoma in both cases. The authors suspect that development of the cholesteatomas was linked to the TECA/LBO surgery in both cases. Cholesteatomas may occur more frequently than currently thought. Even if only slight changes of the bulla wall are detected on CT, early-stage cholesteatoma should be considered. The narrow anatomic conditions in brachycephalic dogs possibly predispose such breeds to develop cholesteatoma after middle ear surgery because complete removal of all inflammatory and epithelial tissue can be more difficult than in other breeds. To the authors' knowledge, this is the first report of an aural cholesteatoma causing sensory deficits of the trigeminal nerve.

Magnetic resonance imaging for the differentiation of neoplastic, inflammatory, and cerebrovascular brain disease in dogs

BACKGROUND

The reliability and validity of magnetic resonance imaging (MRI) for detecting neoplastic, inflammatory, and cerebrovascular brain lesions in dogs are unknown.

OBJECTIVES

To estimate sensitivity, specificity, and inter-rater agreement of MRI for classifying histologically confirmed neoplastic, inflammatory, and cerebrovascular brain disease in dogs.

ANIMALS

One hundred and twenty-one client-owned dogs diagnosed with brain disease (n = 77) or idiopathic epilepsy (n = 44).

METHODS

Retrospective, multi-institutional case series; 3 investigators analyzed MR images for the presence of a brain lesion with and without knowledge of case clinical data. Investigators recorded most likely etiologic category (neoplastic, inflammatory, cerebrovascular) and most likely specific disease for all brain lesions. Sensitivity, specificity, and inter-rater agreement were calculated to estimate diagnostic performance.

RESULTS

MRI was 94.4% sensitive (95% confidence interval [CI] = 88.7, 97.4) and 95.5% specific (95% CI = 89.9, 98.1) for detecting a brain lesion with similarly high performance for classifying neoplastic and inflammatory disease, but was only 38.9% sensitive for classifying cerebrovascular disease (95% CI = 16.1, 67.0). In general, high specificity but not sensitivity was retained for MR diagnosis of specific brain diseases. Inter-rater agreement was very good for overall detection of structural brain lesions (κ = 0.895, 95% CI = 0.792, 0.998, P < .001) and neoplastic lesions, but was only fair for cerebrovascular lesions (κ = 0.299, 95% CI = 0, 0.761, P = .21).

CONCLUSIONS AND CLINICAL IMPORTANCE

MRI is sensitive and specific for identifying brain lesions and classifying disease as inflammatory or neoplastic in dogs. Cerebrovascular disease in general and specific inflammatory, neoplastic, and cerebrovascular brain diseases were frequently misclassified.

Brain abscess in seven cats due to a bite wound: MRI findings, surgical management and outcome

PRESENTATION AND LESION LOCALISATION: Seven adult domestic shorthair cats were presented with a 1- to 6-day history of progressive neurological signs. A focal skin puncture and subcutaneous swelling over the dorsal part of the head were detected on physical examination. Neurological examination indicated lesion(s) in the right forebrain in four cats, multifocal forebrain in one cat, left forebrain in one cat, and multifocal forebrain and brainstem in the remaining cat. In all cats, magnetic resonance imaging revealed a space-occupying forebrain lesion causing a severe mass effect on adjacent brain parenchyma. CLINICAL APPROACH AND OUTCOME: All cats were managed with a combination of medical and surgical treatment. At surgery a small penetrating calvarial fracture was detected in all cats, and a tooth fragment was found within the content of the abscess in two cats. The combination of surgical intervention, intensive care and intravenous antimicrobials led to a return to normal neurological function in five cats.

PRACTICAL RELEVANCE

As this series of cases indicates, successful resolution of a brain abscess due to a bite injury depends on early recognition and combined used of antimicrobials and surgical intervention. A particular aim of surgery is to remove any skull and foreign body (tooth) fragments that may represent a continuing focus of infection.

Presumptive meningoencephalitis secondary to extension of otitis media/interna caused by Streptococcus equi subspecies zooepidemicus in a cat

A 5-year-old castrated male domestic longhair cat was presented with neurological signs consistent with a central vestibular lesion and left Horner's syndrome. Computed tomography images revealed hyperattenuating, moderately contrast-enhancing material within the left tympanic bulla, most consistent with left otitis media/interna. Marked neutrophilic pleocytosis was identified on cerebrospinal fluid analysis. Streptococcus equi subspecies zooepidemicus (SEZ) was isolated from the cerebrospinal fluid. Intracranial extension of otitis media/interna is relatively infrequent in small animals. There are no reports of otitis media/interna caused by SEZ in dogs or cats. This is the first report of otitis media/interna and presumptive secondary meningoencephalitis caused by SEZ in a cat.

Optimising magnetic resonance image quality of the ear in healthy dogs

The aim of this study was to develop an examination protocol for magnetic resonance imaging, in order to display diagnostically important information of the canine middle and inner ear. To ensure that this protocol could also be used as a basis for determining pathological changes, the anatomical structures of the ear were presented in detail. To minimise stress through anaesthesia in live animals, preliminary examinations were carried out on four dog cadavers. During these initial examinations, three-dimensional (3D) sequences proved to be superior to two-dimensional ones. Therefore, only 3D sequences were applied for the main examinations performed on six clinically healthy Beagles. The anonymised MR images were rated by three experienced reviewers using a five-point scale. The most valuable sequence was a T2-weighted CISS sequence (TR = 16.7 ms, TE = 8.08 ms). This sequence proved to be most suitable for illustrating the inner ear structures and enabled good tissue contrasts. The sequence ranked second best was also a T2-weighted DESS sequence (TR = 19 ms, TE = 6 ms), allowing the imaging of the tympanic cavity and enabling 3D reconstruction due to its isotropic voxels. Due to low contrast and strong noise, the other sequences (TSE, FISP, MP RAGE) were not suitable for anatomical illustration of the middle and inner ear.

Mycoplasma felis-associated meningoencephalomyelitis in a cat

Mycoplasmas are frequently isolated from many animal species. In domestic cats, mycoplasmas may be isolated from respiratory and ocular mucosae, but other sites are also occasionally colonized by these organisms. No cases of Mycoplasma species-associated neurologic disease have been reported in cats. We describe a case of Mycoplasma felis-associated meningoencephalitis in a 10-month-old domestic shorthair cat.

Vestibular disease in dogs and cats

The vestibular system is the major sensory (special proprioceptive) system that, along with the general proprioceptive and visual systems, maintains balance. Clinical signs of vestibular disease include asymmetric ataxia, head tilt, and pathologic nystagmus. Neuroanatomic localization of observed vestibular signs to either the peripheral or central components of the vestibular system is paramount to the management of the patient with vestibular dysfunction, as the etiology, diagnostic approaches, and prognoses are dependent on the neuroanatomic diagnosis. This article reviews functional vestibular neuroanatomy as well as the diagnosis and treatment of common causes of small animal vestibular disease.

Surgical management of a canine intracranial abscess due to a bite wound

OBJECTIVE

To describe the successful surgical management of a brain abscess in a dog secondary to bite wound.

CASE SUMMARY

A 10-year-old neutered female Welsh Corgi/Chihuahua, weighing 5.3 kg, was presented for evaluation of seizures, ataxia, and falling to the left 8 days after a presumptive fight with another dog. On examination at presentation, the dog was alert, responsive, and ambulatory with tetra-ataxia, falling to the left, left-sided postural deficits, and absent left menace response. Within 24 hours, the dog progressed to nonambulatory tetraparesis with minimal motor, absent postural reactions of all limbs, left nasal hypalgesia, reduced gag reflex, and depressed mentation. Computed tomographic images of the brain were suggestive of a bite wound fracture of the right parietal bone with secondary meningoencephalitis, right parietal lobe abscessation, and white matter edema adjacent to the bone fracture. A modified right rostrotentorial craniectomy was performed, the abscess was identified, contents of the abscess were removed, and the surgical site was flushed extensively before closing. Corynebacterium spp. was cultured from within the abscess. Within hours of surgery, the dog was quiet but alert, responsive, and sitting up in her cage. In addition to surgical intervention, intensive care, broad-spectrum IV antimicrobials, and supportive therapy led to significant neurologic improvement with only occasional seizures and mild postural reaction deficits of the left hindlimb remaining.

NEW OR UNIQUE INFORMATION PROVIDED

Abscess formation within the CNS is uncommon in dogs and cats and is associated with a high mortality rate. In veterinary medicine the management of brain abscesses is controversial with limited information available regarding treatment. This is the first case report that demonstrates surgical intervention in combination with antimicrobial therapy can be used successfully in the treatment of a canine brain abscess.

Clinical signs, magnetic resonance imaging findings and outcome in 77 cats with vestibular disease: a retrospective study

Medical records of 77 cats that had clinical signs of vestibular disease and magnetic resonance imaging (MRI) of the head were reviewed retrospectively. The aetiological, clinical and MRI characteristics were described and evaluated for a relationship with patient outcome. Forty cats (52%) had signs of central vestibular dysfunction (CVD), which was part of a multifocal disease in 17 cats (43%). The most frequent causes of CVD were inflammatory conditions (18 cats; 45%), including bacterial inflammation as an intracranial extension of otitis interna (five cats; 13%), feline infectious peritonitis (three cats; 8%) and toxoplasmosis (two cats; 5%). Neoplasia (12 cats; 30%) and vascular disease (four cats; 10%) were respectively the second and the third most frequent causes of CVD. Thiamine deficiency was diagnosed in one cat based on MRI findings and improvement following vitamin B(1) supplementation. Of 37 cats (48%) with peripheral vestibular dysfunction (PVD), idiopathic vestibular syndrome (IVS) was suspected in 16 (43%) and otitis media/interna was suspected in 16 (43%). Within the group of cats with evident MRI lesions, the location of the imaged lesions agreed with the clinical classification of vestibular dysfunction in 52/55 (95%) cats. Most of the cats (nine cases; 56%) with presumed IVS had rapid and complete recovery of their clinical signs. As most of these cats presented with progressive clinical signs over 3 weeks they were classified as having 'atypical' IVS to differentiate them from cats with the typical non-progressive IVS. No underlying systemic diseases were documented in any of these cases. Statistically significant predictors of survival included neurolocalisation (central or peripheral vestibular system), age and gender. No difference in survival was observed between cats with presumed idiopathic peripheral syndrome and cats with otitis media/interna.