MAGNETIC RESONANCE IMAGING OF THE INTRATEMPORAL FACIAL NERVE IN IDIOPATHIC FACIAL PARALYSIS IN THE DOG

Neurogenic keratoconjunctivitis sicca in 34 dogs: A case series

OBJECTIVE

To describe the clinical findings, imaging features, underlying conditions, treatment, and progression of dogs presented between 2010 and 2019 with neurogenic keratoconjunctivitis sicca (NKCS).

METHODS

Dogs diagnosed with NKCS were searched in the clinical database. Inclusion criteria were STT-1 readings <15 mm/min, clinical signs of KCS with concurrent ipsilateral xeromycteria.

RESULTS

Thirty-four cases were identified. Mean age at presentation was 8.2 years, median 8.9 years (0.3-14.7). Twenty dogs were male, and 14 dogs were female. Concurrent neurological deficits included facial neuropathy (n = 13, 38%), peripheral vestibular syndrome (n = 10, 29%), and Horner's syndrome (n = 5, 15%). Advanced imaging was acquired in 53% of cases (n = 18). Etiologies included idiopathic (n = 18, 53%), endocrinopathy (n = 6, 18%), otitis interna (n = 4, 12%), head trauma (n = 3, 9%), iatrogenic (post-TECA-LBO, n = 1, 3%), brainstem mass (n = 1, 3%), and an area of inflammation in the pterygopalatine fossa (n = 1, 3%). Treatment for NKCS was initiated in most cases (n = 30, 88%) including: oral pilocarpine 2% and lacrimostimulant (n = 19), oral pilocarpine 2% only (n = 3), or lacrimostimulant only (n = 8). A mean time follow-up of 3.7 months, median 3 months (1-14) was available in 23 cases (68%). Eleven cases with follow-up were responsive (48%) with resolution of the clinical signs in a median time 4 months (1-10), and all of them were treated with oral pilocarpine (±lacrimostimulant).

CONCLUSIONS

Most cases presented as idiopathic NKCS; in others, an underlying cause of facial neuropathy was identified. All responsive cases were treated with oral pilocarpine 2%.

Magnetic resonance imaging of the caudal portion of the digastric muscle in canine idiopathic facial neuropathy

Idiopathic is the most common etiology for acute onset of facial neuropathy in dogs with limited number of studies describing MRI characteristics. A retrospective, observational study was performed using archived records, aiming to describe the MRI features of the caudal portion of the digastric muscle in dogs diagnosed with idiopathic facial neuropathy and to determine correlation with prognosis. Client-owned dogs presented to a referral hospital between 2009 and 2019, diagnosed with unilateral idiopathic facial neuropathy and having undergone MRI, with images including the caudal portion of the digastric muscle, were included (n = 19). MRI appearance of the affected muscle, including degree of muscle atrophy, signal intensity, enhancement post-contrast, and enhancement characteristics of the affected facial nerve, was described and compared to the contralateral, clinically unaffected caudal portion of the digastric muscle. Correlation between MRI appearance and outcome at 1-month and 3-months following onset of clinical signs was investigated. The majority of patients demonstrated some degree of muscle atrophy (n = 17, 89%), hyperintensity in T2W (n = 17, 89%), and pre-contrast T1W (n = 15, 79%) images, as well as contrast enhancement of the affected muscle (n = 14, 74%) and affected facial nerve (n = 9, 47%). There was no statistically significant correlation between atrophy or enhancement of the affected caudal portion of the digastric muscle nor between enhancement of the affected facial nerve and outcome. Hyperintensity both in T2W images and pre-contrast T1W images was significantly correlated with a worse prognosis. Ensuring inclusion and evaluation of this muscle in MRI may therefore be indicated in canine idiopathic facial neuropathy.

Facial nerve paralysis in 64 equids: Clinical variables, diagnosis, and outcome

BACKGROUND

Facial nerve paralysis (FNP) in equids is not well described in the veterinary literature.

OBJECTIVE

To investigate the causes of FNP and associations among clinical variables, diagnosis, and outcome.

ANIMALS

Sixty-four equids presenting with FNP between July 2000 and April 2019. Cases of postanesthetic FNP were excluded.

METHODS

Medical records were retrospectively reviewed. Variables were evaluated for associations with outcomes (diagnosis and case outcome) using logistic regression.

RESULTS

The most common cause of FNP was trauma (n = 20). Additional diagnoses included central nervous system (CNS) disease (n = 16), idiopathic (n = 12, 4 of which had adequate diagnostic investigation and were considered "true" idiopathic, and 8 of which were considered "not investigated" idiopathic), temporohyoid osteoarthropathy (n = 10), otitis media-interna (n = 3), lymphoma (n = 1), iatrogenic as a consequence of infiltration of local anesthetic (n = 1), and clostridial myositis (n = 1). Follow-up was available for 55 (86%) cases. Twenty-nine (53%) equids had full resolution of FNP, 14 (25%) were euthanized, 6 (11%) partially improved, and 6 (11%) were unchanged or worse.

CONCLUSIONS AND CLINICAL IMPORTANCE

If FNP is the consequence of CNS disease, successful treatment of the primary disease likely leads to resolution of FNP. Most cases of FNP in equids are traumatic in origin. True idiopathic cases are uncommon.

Incidence, cause, outcome and possible risk factors associated with facial nerve paralysis in dogs in a Sydney population (2001-2016): a retrospective study

OBJECTIVE

This study aims to assess the incidence and causes of facial nerve paralysis (FNP) in dogs in the Sydney region. Its outcome and possible risk factors are investigated to prognosticate and aid design of diagnostic and treatment plans.

DESIGN

Retrospective case study.

METHODS

Client-owned dogs presented to the University Veterinary Teaching Hospital, Sydney (UVTHS), between 2001 and 2016 with FNP were included (n = 122). The incidence of each cause of FNP was investigated. A reference population of noncases seen at the UVTHS during the same time period was used to study the association between idiopathic facial nerve paralysis (IFNP) and gender, age and breed.

RESULTS

IFNP (29.5%) was the most common diagnosis. Male dogs (odds ratio [OR], 2.3) had increased odds of IFNP compared with female dogs. Age was a significant risk factor for both the occurrence of FNP and IFNP. There was higher occurrence of IFNP among middle-aged dogs (5-13 years) and reduced risk in juvenile dogs (less than 2 years). Cavalier King Charles Spaniels were over-represented for FNP (OR, 6.9) and IFNP (OR, 17.5). For IFNP, 6 of 16 dogs with known follow-up showed definitive resolution within 3 years of diagnosis. Concurrent vestibular signs were common in dogs with middle/inner ear abnormality and intracranial disease; and were also seen in 50% of dogs with IFNP.

CONCLUSION

The results of this study demonstrate statistical predilections in age, gender and breed for IFNP. Guarded prognosis for recovery should be given to dogs diagnosed with IFNP and supportive management instigated.

Pros and cons of low-field magnetic resonance imaging in veterinary practice

Low-field (LF) (0.2-0.4T) magnetic resonance (MR) imaging predominates in veterinary practice. Advantages of LF MR include reduced costs, better patient access, and greater safety. High quality examinations can be achieved using appropriate protocols and investing more scanning time than with high-field (HF) systems. The main disadvantage of LF MR is the reduced signal to noise ratio compared with HF systems. LF MR protocols for small animal brain and spine imaging are described.

Unilateral facial paresis secondary to a suspected brainstem arachnoid cyst in a Maltese dog

An 8-year-old, intact female Maltese dog was presented with decreased tear production and unilateral loss of eye blinking. Neuro-ophthalmic examination and brain magnetic resonance imaging were performed to determine the origin of facial paresis. A cystic lesion in the left pontomedullary region which displayed equal intensity to cerebrospinal fluid was revealed. Hyposignality was noted on fluid attenuated inversion recovery sequences, and the lesion was suggestive of an arachnoid cyst. This report described unilateral facial nerve dysfunction that resulted from a suspected brainstem arachnoid cyst in an unusual anatomic location.