Veterinary Neurology

Crabbing Dog

Noweia — Mon, 26 Nov 2018 14:16:17 GMT

This video was first uploaded Sep 14, 2009, re-uploaded Nov 26 2018 after site upgrade.

Spot the pathology

Liz Barton — Mon, 09 Jul 2018 22:55:20 GMT

Forget the stone... which was entirely asymptomatic. This 4 yo spaniel had been fine until an episode of severe trauma

Seizures in a German Shepherd Puppy

Alex Gough — Fri, 29 Jun 2018 11:15:47 GMT

Case presentation:
A four month old male German Shepherd puppy presented with a history of frequent generalised seizures for about 3 weeks, with some odd episodes of standing still and crouching, and some salivation. Neurological examination was unremarkable.

Question. What is your neurolocalistion?
Question. What are your most likely differentials?

For investigations, imaging, and the answer to these questions, please scroll down the page.

Investigations
Routine haematology and biochemistry, faecal examination by Baermann's technique for lungworm, dynamic bile acids and serology for Toxoplasma/Neospora were all normal.

Imaging
MRI showed a severe left sided brain malformation with the caudal left hemisphere replaced by CSF. See figs 1 and 2 below.

Fig 1. (above) T1 weighted parasagittal MRI of the brain, showing CSF in the region where the caudal cerebral hemisphere should be.

Fig 2. Transvese T1-weighted MRI showing CSF in place of cerebral tissue on the left.

Treatment
Levetiracetam was chosen as an initial treatment for its quick onset of activity. The prognosis was suspected to be poor.

Outcome
No further seizure activity was observed for 7 days. The puppy was unfortunately found dead one morning, soon after this.

Post mortem examination
A small defect in the calvarium was noted, which was covered in meninges (fig 3). The gross post mortem findings were as expected from the MRIs, with the caudal third of the the left cerebral hemisphere missing, replaced with CSF (fig 4). Histology of the brain also showed evidence of acute meningitis.

Fig 3. Post mortem examination of the puppy. The scissors are pointing to a defect in the calvarium covered by meninges.

Fig 4. Post mortem examination showing the small left cerebral hemisphere (on the right of this picture)

Final diagnosis
Porencephaly, with acute meningitis

Discussion
Porencephaly is a rare developmental condition in which a cavity is found in the skull in place of part of the cerebral hemispheres. In this case, the main signs were seizures, which are a common manifestation of forebrain lesions. Some behavioural abnormalities in this case could also be attributed to the forebrain disease. There is no specific treatment. Intracranial pressure is not elevated, so ventriculoperitoneal shunting is not indicated. Management of the condition is aimed at control of clinical signs. The prognosis is poor however. This case was further complicated by the surprising post-mortem discovery of acute meningitis. The cause and significance of this is not known. A CSF tap was not performed, because of initial fears regarding possible raised intracranial pressure making the procedure more dangerous. Whether treatment of the meningitis would have led to a better long term outcome in this case is debatable.

Question. What is your neurolocalistion?
Answer. Seizures and behavioural changes suggest a forebrain localisation

Question. What are your most likely differentials?
Answer. Major differentials in a young puppy include metabolic disease such as hepatic encephaopathy, infectious disease such as protozoal encephalitis, immune-mediated disease, and anomalous disease.

First published Thu, Mar 10 2011

Seizures in a young Great Dane

Alex Gough — Fri, 29 Jun 2018 11:06:37 GMT

Case presentation
An 18 month old female neutered Great Dane presented with an acute history of generalised seizures. She had been off colour for the previous two weeks. Physical examination revealed a palpable mass over the left caudal ribs. Neurological examination was initally unremarkable, but after a second seizure, she was temporarily blind and disoriented.

Question: What is your neurolocalisation?
Question: What are your most likely differentials?

For further investigations, imaging and the answers to these questions, please scroll down the page.

Further investigations
Routine haematology showed a marked neutrophilia. Ultrasonography of the rib mass revealed the mass extended some way internally. MRI was performed of the brain to attempt to identify the cause of the seizures. This revealed a mass with a ring pattern of contrast enhancement in the right forebrain, with associated oedema (fig 1). CSF analysis showed a mild pleocytosis. MRI of the thorax also helped identify the size and invasiveness of the mass (fig 2). Trucut biopsies were taken of the thoracic mass, which revealed an undifferentiated sarcoma, thought possibly to be a rhabdomyosarcoma. The brain mass was presumed to be a metastasis of this tumour. Palliation with phenobarbitone was commenced, but unfortunately the outlook for this dog was poor.

Fig 1: T1 + gadolinium transverse MRI scan showing a ring enhancing mass in the right forebrain

Fig 2: T1 weighted MRI of soft tissue mass over the lateral thorax

Discussion
Most dogs that experience their first seizure aged between 6 months and 6 years, which are neurologically normal interictally, do not have abnormalities diagnosed on further investigations and are diagnosed with idiopathic epilepsy. One paper looking at MRI findings in dogs with epilepsy found significant MRI abnormalities in only 1/46 dogs under 6 years of age, compared with 8/30 dogs over the age of 6 (Smith, Talbot & Jeffery 2007). It was somewhat surprising to find a brain tumour in a dog this young. This tumour was presumed to be secondary to the mass in the thoracic wall. In one paper looking at secondary intracranial neoplasia in dogs, 29% were haemangiosarcomas, 25% were pituitary tumours, 12% were lymphomas and 12% were metastatic carcinomas (Snyder et al 2008).

References:
Smith, Talbot & Jeffery (2007) Veterinary Journal 176, 320
Synder et al (2008) JVIM. 22, 172

Question. What is your neurolocalistion?
Answer. Seizures suggest forebrain disease. Blindness can be caused by ophthalmological disease, and by lesions in various areas of the nervous system, but in this case is likely a post-ictal change as it was temporary.

Question. What are your most likely differentials?
Answer. A dog of this age with seizures is most likely to be suffering from idiopathic epilepsy. Other possibilities include metabolic disease such as hepatic encephalopathy, immune-mediated and infectious disease, and less likely, neoplasia.

First published: Tue, Mar 15 2011

Masticatory muscle atrophy in a Rottweiler

Alex Gough — Fri, 29 Jun 2018 10:47:23 GMT

Case presentation
A 9 year old male neutered Rottweiler presented with a history of unilateral left sided masticatory muscle atrophy. There was no history of difficulties with prehension, or pain on opening the jaw. Physical examination revealed a dramatic left sided loss of masticatory muscle(fig 1). The right sided masticatory muscle was normal on palpation. Neurological examination revealed that the corneal reflex and nasal mucosal sensation were absent on the left but normal on the right. Menace and palpebral reflexes were normal. No proprioceptive deficits were found.

Question: What is your neurolocalisation?
Question: What are your most likely differentials?

For further investigations, discussion and the answers to these questions, please scroll down the page.

Further investigations
Routine haematology and biochemistry were unremarkable. MRI of the brain was performed (Figs 2-5 below)

Fig 2: T1 weighted dorsal view of the brain stem. The trigeminal nerve on the left (arrowed) is thicker than the right.

Fig 3: T1 weighted dorsal view of the brain stem post contrast. The trigeminal nerve on the left (arrowed) has taken up more contrast than the right.

Fig 4: T1 weighted transverse MRI scan of brain, showing mass adjacent to brain stem (arrowed) in region of trigeminal nerve. The dramatic left sided masticatory muscle wasting is also evident in this image.

Fig 5: T1 weighted transverse MRI scan of brain, post contrast, showing mass adjacent to brain stem (arrowed) in region of trigeminal nerve.

Diagnosis
Malignant nerve sheath tumour of the trigeminal nerve.

Follow up
No specific treatment was given. The dog was euthanased 12 months later due to heart failure secondary to dilated cardiomyopathy.

Discussion
The slow onset of signs in this case, together with the unilateral masticatory muscle wasting and the signs attributable to deficits of the trigeminal nerve made a presumptive diagnosis of trigeminal nerve sheath tumour likely. Imaging findings were supportive of a trigeminal nerve sheath tumour. Malignant nerve sheath tumours are slowly progressive, and although surgery is reported as possible, the survival times without surgery can be substantial (range of 5 to 21 months in one study, Bagley et al 1998). Another differential for these imaging findings is trigeminal neuritis. This condition usually presents as a relatively acute, idiopathic, bilateral condition, causing a dropped jaw, and is usually self-limiting. However, in one study of the imaging findings of 6 cases of acquired trigeminal lesions (Schulz et al 2007), 4 cases were found histologically to be malignant nerve sheath tumours, but two were trigeminal neuritis. In both disease processes, masticatory muscle atrophy was seen, with hyperintensitiy of the atrophied muscle, and in both diseases there was increased contrast uptake in the affected nerves. The trigeminal nerve was diffusely thickened in cases of trigeminal neuritis, but had a lobulated or mass-like lesion in trigeminal nerve sheath tumour (as can be seen in figure 5 above). Trigeminal nerve sheath tumour was considered most likely in this case, but histology would be required to differentiate definitively between these two conditions.

References:
Bagley et al (1998), JAAHA, 34, 19
Schulz et al (2007), Vet Rad & Ult, 48, 101

Question. What is your neurolocalistion?
Answer. The corneal sensation and nasal mucosal sensation travel via the trigeminal nerve. The trigeminal nerve supplies motor innervation to the masticatory muscles. The neurolocalisation is therefore the left trigeminal nerve or the left brain stem. The lack of proprioceptive deficits make brainstem disease less likely.

Question. What are your most likely differentials?
Answer. The chronic and progressive nature of the disease make neoplasia the most likely differential, including malignant nerve sheath tumour and lymphoma. Trigeminal neuritis could also fit with the findings, see discussion. Masticatory myopathy is another possible cause of masticatory muscle atrophy. This is usually bilateral, but can be unilateral. However, it is possible that prior to the availability of MRI, cases of trigeminal nerve sheath tumours were misdiagnosed as unilateral masticatory myopathy. In this case, masticatory myopathy would not explain the sensory deficits in the cranial nerves.

First published Fri, Mar 18 2011

Ataxia and nasal discharge in a young cat

Alex Gough — Fri, 29 Jun 2018 10:01:35 GMT

Case presentation
A 3 year old neutered female DSH cat presented with a 7 day history of cat flu like signs, including sneezing and a right sided purulent discharge. There was minimal response to antibiotic treatment. She then developed a swelling over the right frontal sinus, became ataxic and started to head press. Examination revealed her to be obtunded and ataxic with proprioceptive deficits in all four limbs.

Question: What is your neurolocalisation?
Question: What are your likely differentials?

For further investigations, discussion and the answer to these questions, please scroll down the page.

Further investigations
A number of tests had been performed at the referring veterinary practice. Routine haematology and biochemistry at the referring vets were unremarkable. A nasal biopsy had shown a granulomatous inflammation, and a Pasteurella species was grown. FIV and FeLV testing was negative. Aspergillus serology was negative. Nasal radiography showed soft tissue density within the nasal cavity but no osteolysis. MRI of the brain was performed at Bath Veterinary Referrals.

Fig 1. T1 weighted parasagittal MRI of the brain and nasal cavity.

Fig 2. T1 weighted parasagittal MRI scan of the brain and nasal cavity post gadolinium contrast. Compared to figure 1, it can be seen there is contrast uptake in the nasal cavity and extending into the frontal lobes of the cerebrum.

Fig 3. T1 weighted dorsal view MRI of the brain and nasal cavity

Fig 4. T1 weighted dorsal MRI of brain and nasal cavity after gadolinium contrast. There is contrast enhancement of a mass extending from the nasal cavity through the cribriform plate into the frontal lobes.

Outcome
The owner elected euthanasia while the cat was still under anaesthetic at this stage. A post mortem examination was carried out with the owner's permission (fig 5)

Fig 5. Post mortem examination of this case. Rostral is to the bottom of the picture. An irregular mass can be seen filling the nasal cavity and extending through the cribriform plate into the brain. Some purulent discharge from the fronal sinus is also visible on the right of the picture.

Histology demonstrated the mass to be nasal lymphoma, with extension into the ethmoidal cribriform plates, frontal meninges and into the frontal cerebral cortex.

Discussion
Nasal lymphoma is one of the most common nasal tumours in cats, and the nasal cavity is the most commonly affected site for extranodal neoplasia in cats. One retrospective study of 97 cats with nasal lymphoma showed an overall median survival time of 172 days, with no difference being found between cats that were treated with radiotherapy alone, chemotherapy alone or radiotherapy + chemotherapy (Haney et al 2009).

References:
Haney et al (2009), JVIM, 23, 287
Sykes et al (2010), JVIM, 24, 1427

Question. What is your neurolocalistion?
Answer. Proprioceptive deficits can arise from lesions in the forebrain, brain stem, spinal cord, and peripheral nerves. Assuming the obtundation was related to the ataxia, this implies forebrain involvement.

Question. What are your most likely differentials?
Answer. If the nasal signs were related to the neurological signs, then a process affecting both the nasal cavity and forebrain is suspected. Differentials include a neoplastic disease extending locally from nasal cavity to brain, or less likely a fungal disease. Cryptococcosis can affect the brain and the nasal cavity, and has been reported to cause gelatinous pseudocyst and granulomatous mass lesions in the CNS (Sykes et al 2010). However cryptococcosis is uncommon in the UK. Other differentials include viral infections such as FIP, FIV and FeLV.

First published Thu, Mar 24 2011

Seizures in an old Boxer dog

Alex Gough — Wed, 16 Mar 2011 09:18:39 GMT

Case presentation
An 8 year old female neutered Boxer presented with a history of recent onset generalised seizures. Physical and neurological examinations were unremarkable.

Question. What is your neurolocalisation?
Question. What are your most likely differentials?

For further investigations, imaging, diagnosis and the answers to these questions, please scroll down the page.

Question. What is your neurolocalistion?
Answer. Seizures suggest forebrain disease.

Question. What are your most likely differentials?
Answer. The breed and age are suggestive of neoplasia. Other differentials include metabolic disease, immune-mediated disease, infectious disease and late onset idiopathic epilepsy.

Further investigations
Routine haematology, biochemistry and protozoal serology were unremarkable. MRI of the brain was performed (fig 1.) which showed a poorly contrast enhancing mass, which was bright on T2, in the left forebrain.

Fig 1. T2 weighted transverse MRI scan of brain. There is a large hyperintense mass in the left cerebral hemisphere, which is showing some mass effect as evidenced by compression of the lateral ventricle. Note the black shadow in the bottom left of the picture, which is artefact due to the metal spring in the cuff of the endotracheal tube.

Diagnosis
Brain tumour

Question: What is the likely type of tumour, and what is the best treatment?

For the answer to this question, please scroll down the page.

Question. What is the likely type of tumour, and what is the best treatment?
Answer. Boxers are prone to develop gliomas. They can also get meningiomas, but these tend to have a good, homogenous contrast uptake, whereas gliomas usually poorly enhance or show a ring enhancement. Histopathology is necessary to be certain of the diagnosis however. Gliomas are invasive tumours and surgical removal is rarely indicated. Treatment options include palliation with steroids to reduce peritumoural oedema, chemotherapy with lomustine, and radiotherapy. Radiotherapy is generally well tolerated, and can lead to durable remissions.

Treatment and follow up
Treatment consisted of radiotherapy plus phenobarbitone. Seizures resolved, and the phenobarbitone was weaned off.

MRI was performed 6 months after the radiotherapy which showed the tumour was no longer evident (see fig 2).

Fig 2. T2 weighted transverse MRI of the same Boxer as in figure 1, 6 months after radiotherapy.

Discussion
Boxers are strongly predisposed to develop gliomas, and Boxers that develop seizures, even if they are less than 6 years old, should be considered for MRI imaging to aid in reaching a diagnosis. There are several treatment options, but radiotherapy, where available, probably gives the longest survival times, and is usually well -tolerated.