Miscellaneous neurological disorderss Flashcards
Describe the neurological pathway of ocular sympathetic innervation implicated in Horner’s syndrome
The pathway that enables sympathetic innervation of the eye begins in the hypothalamus and descends in the cervical spine cord along the tectotegmental tracts
These neurons then synapse with sympathetic preganglionic neurons in the first two segments of the thoracic spinal cord which then pass through the brachial plexus and ascend in the vagosympathetic trunk
- These then synapse with neurons in the cranial cervical ganglion
These nerves then travel via the middle ear to the eye where they innervate the dilator smooth muscle of the eye and the muscles that help position the third eyelid, upper eyelid, and globe within the orbital socket
What are the clinical signs associated with Horner’s syndrome
Five signs constitute Horner’s syndrome:
- miosis
- ptosis of the upper eyelid
- third eyelid prolapse
- enophtalmos
- vasodilation of the vessels in the skin on the affected side of the face
What are the main causes of Horner’s syndrome
Lesions anywhere along the pathway can cause Horner’s syndrome
The condition is most commonly seen with:
- middle ear disease (e.g., otitis media, inflammatory polyps)
- brachial plexus injuries
- disease of spinal cord segments T1-T3
- lesions in the cranial thorax
- lesion in the area of the neck where the vagosympathetic trunk traverses
Rarely hypothalamic and cervical spinal cord lesions will result in Horner’s syndrome
- these are typically accompanied by other neurological deficits
What is Dysautonomia (Key-Gakell syndrome)
This is a polyneuropathy involving the autonomic nervoous system
- mainly affecting young adult DSH cats
- it seems to have a restricted geographical spread (i.e., UK and midwestern USA) prompting the speculation that a neurotoxin may be involved
What are the clinical signs of Dysautonomia
Affected cats have a variety of clinical signs that may either be acute in onset or progressive over a few days
Clinical signs include:
- bilateral mydriasis that is not responsive to light
- bilateral third eyelid prolapse
- dry oral and nasal mucous membranes
- megaesophagus, vomiting, constipation
- bradycardia
- incontinence or urine retention
How can you reach a diagnosis of dysautonomia
The diagnosis is achieved using a combination of:
- clinical signs
- the ocular pilocarpine test (i.e., administration of 1% pilocarpine drops will produce constriction of the pupils in affected cats only)
- possibly the finding of subnormal levels of noradrenaline and adrenaline in plasma and urine of affected cats
What is the clinical presentation for feline hyperesthesia syndrome
Feline hyperesthesia syndrome is characterized by behaviors such as biting and frantic grooming of the tail, flank, and lumbar areas, accompanied by writhing and twitching of the skin in these areas
- these episodes may arise spontaneously or be induced by brushing or grooming the tail-base area of the cat
The cat often seems agitated, may have mydriatic pupils and may vocalize and run around or attempt to bite the person petting it
Some extreme cases may progress to overt seizure activity
What would be your treatment plan for feline hyperesthesia syndrome
Treatment trials may be required, in spite of the absence of an obvious diagnosis:
- prednisolone 1mg/kg every 12-24h for 3-5 days
- phenobarbitone 2mg/kg PO, q12h for 14 days
- gabapentin (1st line) 5-10 mg/kg, PO, 2-3 times daily for 3-5 days
- topiramate (2nd line) 2.5 mg/kg, PO, SID/BID increasing up to 10 mg/kg BID
- clomipramine 0.5 mg/kg, PO, q24h for 3-4 weeks
- fluoxetine 0.5-2.0 mg/kg, PO, q24h for 4-6 weeks
