Magnetic resonance diagnosis: cavernous sinus syndrome in a dog

Variation in the MRI appearance of the canine pituitary gland

A recent publication described pathological findings in the pituitary gland incidentally discovered during routine necropsies of the brain of dogs and cats; however, imaging characteristics of these lesions were not reported. Aims of this retrospective, observational study were to characterize MRI variants and incidental lesions in pituitary glands of dogs with no clinical signs of pituitary disease. Cranial MRIs from dogs with no suspicion of pituitary disease, based on history and presenting clinical signs, were retrieved from a veterinary teleradiology database during the period of January 2014 to January 2016. Images were reinterpreted by two observers and pituitary lesions were described based on consensus. A total of 580 scans were evaluated and pituitary lesions were detected in 78 dogs (13.44%). Pituitary cystic lesions were the most common finding and occurred in 31 dogs (5.34%). Of these 31 dogs, the majority (74%) were of toy or brachycephalic breed. Partial or total empty sella lesions were detected in 14 dogs (2.41%), and all of these were small or toy breeds. A significantly increased incidence of the partial empty sella lesion was found in male dogs (P = .034). Pituitary lesions greater than 1 cm occurred rarely (0.69%). There was a significant association between low-field (LF) MRI strength and detection of a partial or total empty sella lesion (P = .0112), and detection of a pituitary lesion greater than 1 cm (P = .0125). A significant difference was present between the MRI field strength (FS) that identified pituitary cysts and the FS that detected an empty sella (P = .0068), with the former being a high FS and the latter a LF strength. The findings from this study indicated that up to 13% of dogs with no presenting clinical signs of pituitary disease may have MRI pituitary lesions.

Persistent Bilateral Mydriasis Associated With a Pituitary Adenoma in a Horse

Severe bilateral mydriasis and bilaterally decreased vision were observed in a 23-year-old crossbred warmblood gelding with a history of pituitary pars intermedia dysfunction. Ten years after the onset of clinical signs, it was killed humanely because of worsening of clinical signs and loss of therapeutic responsiveness. Postmortem examination of the head was performed to confirm the suspected pituitary neoplasm and to investigate secondary oculomotor lesions. Pathomorphologic examination revealed an expansile space-occupying pituitary adenoma and degenerative changes in the preganglionic oculomotor nerve, ciliary ganglion, and optic chiasm. The ocular clinical findings share features of a cavernous sinus syndrome.

Cavernous sinus syndrome in dogs and cats: case series (2002-2015)

The cavernous sinus (CS) is a paired venous sinus that runs along either side of the pituitary gland on the floor of the calvarium. Cavernous sinus syndrome (CSS) refers to deficits in more than one of the cranial nerves III, IV, V, and VI, as they are in close association in this region. The purpose of this study was to identify the presenting complaints, neurologic findings, diagnosis, and outcomes in dogs and cats with confirmed cavernous sinus syndrome (CSS). Medical records between 2002 and 2015 were reviewed. Inclusion criteria were neurologic signs consistent with CSS and advanced imaging and/or post-mortem examination. Thirteen dogs and 2 cats were included. Twelve dogs received advanced imaging. Post-mortem examination was performed on 2 cats and 3 dogs. Dogs were 6 -13 years (mean= 10.8 years) of age and comprised of several different breeds. Both cats were male neutered domestic shorthair, ages 3 and 14 years. Presenting complaints included mydriasis (N=4), behavior changes (N=3), hyporexia (N=3), ptosis (N=2), ataxia (N=2), pain (N=2), weakness (N=2), lethargy (N=2), and one each of epiphora, ocular swelling, polydipsia, seizures, facial muscle atrophy, dysphagia, and head tilt. Neurologic signs included ophthalmoparesis/plegia (N=13), reduced/absent pupillary light response (N= 11), mydriasis (N= 10), reduced/absent corneal sensation (N= 7), ptosis (N= 6), reduced facial sensation (N= 2), and enophthalmos (N=1). Thirteen patients had a mass lesion within the cavernous sinus, 6 of which were confirmed neoplastic via histopathology. Median survival time for the 4 patients treated with radiation therapy was 1035 days (range 150-2280). Median survival for the 4 patients that received medical treatment was 360 days (range 7-1260 days), and for the 5 non-treated patients 14 days (range 0-90 days). In conclusion mydriasis and ophthalmoplegia are common signs of CSS. A mass lesion within the CS is the most common cause. Survival time may be improved with radiation therapy.

Clinical signs, imaging findings, and outcome in twelve cats with internal ophthalmoparesis/ophthalmoplegia

OBJECTIVE

To retrospectively evaluate the clinical signs, imaging findings, and outcome of feline internal ophthalmoparesis/ophthalmoplegia.

PROCEDURE

Medical records were reviewed from 2008 to 2015. Inclusion criteria included cats that presented with internal ophthalmoparesis/ophthalmoplegia, underwent diagnostic imaging, and had follow-up information available.

RESULTS

Twelve cases of feline internal ophthalmoparesis/ophthalmoplegia were identified. Nine cats were unilaterally affected, and three cats were bilaterally affected. Affected cats had a median age of 10.54 years (range 5.75 to 13.17), and both sexes of varying breeds were affected (nine males; three females). Clinical signs including abnormal mental status (n = 9; 75%) and additional neurologic abnormalities (n = 10; 83%) were observed. Magnetic resonance imaging and/or computed tomography (MRI/CT) of the head were performed in ten cats, revealing a mass lesion in all cases with varying locations. Multicentric lymphoma was diagnosed in two cats via abdominal ultrasound and cytology. All twelve cats were euthanized due to deterioration of clinical signs and/or quality-of-life concerns. Median time from diagnosis to euthanasia was 3.5 days (range 0 to 80 days).

CONCLUSIONS

Feline internal ophthalmoparesis/ophthalmoplegia rarely presents as the sole clinical sign in a referral hospital. Advanced imaging (MRI/CT) may be necessary to reach a definitive diagnosis in these cases. However, abdominal ultrasound would be advocated in cats with systemic clinical signs as a less expensive and less invasive diagnostic test to further investigate the possible etiology of internal ophthalmoparesis/ophthalmoplegia prior to advanced imaging. Feline cases with internal ophthalmoparesis/ophthalmoplegia associated with other intracranial signs and/or systemic clinical signs have a poor prognosis.

Cavernous sinus syndrome due to osteochondromatosis in a cat

A 1-year-old sexually intact male Korat cat was referred for ophthalmological consultation due to anisocoria. Mydriasis with external ophthalmoplegia and absence of pupillary light responses in the right eye and nasofacial hypalgesia were seen. Cavernous sinus syndrome (CSS) was suspected. Bilateral deformities of the jaw and phalangeal bones, severe spinal pain and abnormal conformation of the lumbar spine were also present. Radiographic examination revealed several mineralised masses in the appendicular and axial skeleton, indicative of multiple cartilaginous exostoses. For further investigation of the CSS-related neurological deficits, the cat underwent computed tomography (CT) examination of the skull. CT images revealed a non-vascularised, calcified, amorphous mass originating from the right lateral skull base and superimposing on the sella turcica. Based on the severity of diffuse lesions and owing to the clinical signs of extreme pain, the cat was euthanased. A diffuse skeletal and intracranial osteochondromatosis was diagnosed histologically.

Pseudolayering artefact on postcontrast magnetic resonance images of the bladder of 18 dogs and three cats

An artefact was observed on postcontrast magnetic resonance imaging (mri) of the urinary bladder of several small animals; it took the form of a dark layer in the dependent (dorsal) part of the bladder, with a thin hyperintense layer on top of it, and a hypointense signal in the rest of the non-dependent (ventral) part. The mri database was searched for animals with T1-weighted images of the urinary bladder after the injection of gadolinium. Eighteen dogs and three cats were included in the study. The artefact was observed in 16 of the animals on the postcontrast images but not on the T1-weighted and T2-weighted precontrast images. A phantom experiment showed that the signal intensity observed on T1-weighted images decreased rapidly as the concentration of gadolinium increased from 6.25 mmol/l to 25 mmol/l. It is hypothesised that the early excretion of concentrated gadolinium into the bladder causes the pseudolayering artefact observed, which has also been reported in human patients.

Computed tomographic diagnosis of unilateral cavernous sinus syndrome caused by a chondrosarcoma in a dog: A case report

An eight-year old Rottweiler dog was presented with signs of enophthalmia, ptosis, anisocoria and mydriasis of the right eye, which showed visual disturbance, reduced or absent reflexes, and ophthalmoplegia. Consensual pupillary light reflex was also absent in the left eye. These neurological deficits were compatible with cavernous sinus syndrome. Computed tomography images of the cavernous sinus and the optical fissure revealed a mildly calcified mass arising from the right presphenoid bone extending further caudally into the orbital foramina. This extension of the mass affected the normal function of several cranial nerves. The dog was euthanased within one year of the initial presentation following development of forebrain signs. A chondrosarcoma was diagnosed histologically after necropsy.

MAGNETIC RESONANCE IMAGING FEATURES OF PRESUMED NORMAL HEAD AND NECK LYMPH NODES IN DOGS

To document the magnetic resonance imaging appearance of presumed normal lymph nodes of the head and neck in the dog, 91 studies of dogs with no detectable disease in the head acquired on a low-field unit were reviewed. If lymph nodes were imaged, symmetry, signal intensity, homogeneity, and size as well as the relation to the surrounding fat were noted. To improve the description of lymph node topography, we used corresponding E12 plastinated embedded sections of a dog. Compared with surrounding fat, lymph nodes were hypointense in T1 images. In T1-weighted images after intravenous contrast medium lymph nodes were isointense. In T2-weighted images, lymph nodes were slightly hypointense to surrounding fat. In T1 and T2 images, a hypointense band, created by the chemical shift artifact, could be seen at the lymph node-fat boundary along the frequency encoding gradient. In some dogs the lymph node hilus was characterized by vessels indenting the capsule of the lymph node. The facial vein is a consistent landmark to identify mandibular lymph nodes, and the mandibular salivary gland is a useful landmark to localize the medial pharyngeal lymph nodes. The parotid salivary gland or the external acoustic meatus were useful markers to identify the parotid lymph nodes, which were not consistently seen. In some dogs, nodules within the lymphoreticular tissue of the soft palate were seen.

Bilateral cavernous sinus syndrome in dogs: 6 cases (1999-2004)

OBJECTIVE

To determine clinical features, diagnostic imaging abnormalities, underlying disease, disease progression, and outcome in dogs with bilateral cavernous sinus syndrome.

DESIGN

Retrospective study.

ANIMALS

6 dogs.

PROCEDURE

Dogs were included if clinical signs consistent with bilateral cavernous sinus syndrome (i.e., deficits of the third, fourth, and sixth cranial nerves and at least 1 of the first 2 branches of the fifth cranial nerve) were present and a lesion of the cavernous sinus was identified by means of diagnostic imaging or postmortem examination.

RESULTS

5 dogs were evaluated because of problems referable to abnormal ocular motility or pupillomotor dysfunction, and 1 dog was evaluated because of partial motor seizures involving the face and bilateral mydriasis. Four dogs had neurologic signs referable to an extrasinusoidal lesion at the time of initial examination, and the remaining 2 dogs eventually developed extrasinusoidal signs. Besides neuroanatomic location, the only consistent neuroimaging feature was variably intense, heterogeneous enhancement of cavernous sinus lesions. Neoplasia was histologically confirmed as the underlying cause in 5 of the dogs and was suspected in the remaining dog. Median survival time for the 4 dogs that were treated was 199 days (range, 16 to 392 days).

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that bilateral cavernous sinus syndrome is rare in dogs but should be suspected in dogs with compatible clinical signs. Affected dogs have a poor prognosis, and dogs with clinical signs of bilateral cavernous sinus syndrome should be systematically evaluated for neoplastic disease.