Immune Mediaged NS Diseases Flashcards
Immune mediated disease
Abnormal or self directed immune responses to the bodies own tissue and cells specifically in the CNS
Localization of inflammatory or neuro degenerative diseases
Often multi focal and present w multi focal signs
Animals with meningoencephlomyelitis
Often have no systemic abnormalities
Important tests for immune mediated neuro diseases
MRI, CSF analysis, serology, genetic test
What types of meningoencephalitis are recognized
Infectious
Immune-mediated* more common
Risk with MRI and CSF
Results can be normal which shouldn’t rule out presence of disesase
MUE
Meningoencephalitis of unknown etiology
Definitive diagnosis for MUE
Neuro pathologic exam
Brain biopsy
Presumptive antemortem diagnosis
Appropriate signalment /signs
Clinical neurologic dysfunction referable to brain
Compatible lesions on cross sections images
CSF analysis
Exclusion of infectious diseases w serology
Variations of MUE
Ganulomatous meingoencephalitis *most common
Necrotizing encephalitides (NME)
Eosinophilic meningoencephalitis (EME)
Ganulomatous meningoencephalitis (GME)
Giant macrophages mixed w lymphocytic inflammation
Disseminated form (typical)
Focal form (macrogranulomatous)
Ocular form (ocular neuritis)
Disseminated form of GME
multi focal neurologic presentation with multi focal lesions
Focal form of GME
Macrogranulomatous
Single mass like lesion in brain, often appears like tumor on imaging
Ocular form of GME
Presents as optic neuritis and BLINDNESS only
Necrotizing encephalitides
Necrotizing meningoencephalitis (NME) -gray matter
Necrotizing leukoencephalitis (NLE) - white matter
Eosinophilic meningoencephalitis
EME - commonly presents as eosinophilic inflammation in CNS
GME
Most common MUE variant (up to 30% )
Female, small/toy breeds - 4.5years
GME clinically presents of brainstem and SC disease (typically cervical)
Affects white matter of brain
NME
Younger age onset 2.5 yr
Predominately causes forebrain signs
95% of pugs w NME have structural epilepsy
Progresses readily
NME causes
Non-suppurative inflammation of letomeninges w extension into underlying cerebrum & asymmetric necrosis of neuropil
NME genetic testing
Susceptibility to NME in pugs is associated w DLA regions of chromosome 12
~11% of tests pugs S/S 1:8 develop NME
S/S pugs
Have 2 copies of NME susceptibility markers
13x more likely to develop NME in lifetime
Test results for NME
N/N - no copies of NME marker = low risk
N/S - one copy of NME marker = low risk
S/S - two copies of NME marker = 13x more likely
EME
Rare considering
Middle Ages large breed dogs
Can cause any signs of brain disease
More biologically benign than other MUE variants = better clinical prognosis
EME diagnosis
Inflammatory CSF with predominately eosinophils (>50%)
Differentials for eosinophilic pleocytosis
- protozoal or fungal
- parasitic migration
Empirical therapy for MUE treatment
Life threatening signs of ME
Clindamycin, doxycycline, Enrofloxacin
Outcome with no further diagnostics MUE
Continue antibiotics for 3 weeks
If no response or clinical decline start prednisone
Outcome of treatment with further testing MUE
Brain imaging, CSF support, submit titers
CSF support ME, submit titers
Treat based on result of titers, if all negative of clinical decline occurs start MUE therapy
MUE treatment
Corticosteroids are the most common and most efficacious therapy
- prednisone
Pred + cyclosporine, CCNU, Cytosar, leflunomide, procarbazine
- brain irradiation
MUE prognosis
Lifelong therapy is often required
33% of dogs die within first month of diagnosis regardless of treatment
33% of dogs clinically improve but have persistent & significant neurological dysfunction
33% of dogs experience dramatic and durable clinical improvement
Difficult to predict how patients will react
Feline MUE
Uncommon in cats
Infectious etiologies of meningoencephalitis is more common in cats than immune mediated
Often seen in middle aged to older cats
Presentation of feline MUE
Multi focal clinical signs in 67% of cats
33% of cats w MUE have systemic signs
33% of cats w MUE present with SC disease
Diagnostic methods is similar to dogs
Prognosis is good to excellent for cats
Steroid responsive tumor syndrome
Idiopathic (acute onset) steroid responsive tremors, idiopathic cerebellitis, young small breeds
“Little white shaker disease”
treating steroid responsive tremor syndrome
Prednisone, taper for 1 month
Prognosis is excellent, relapse is possible
Cranial neuropathies
Isolated or multiple dysfunction of cranial nerves without other neurological deficits
Idiopathic etiology is most common cause of cranial neuropathies
Commonalities in cranial neuropathies
All idiopathic neuropathies have suspected immune mediated basis
Most idiopathic CN are transient and self limiting
None of the idiopathic CN are life threatening
Have been reported in multiple CNN
Trigeminal neuropathy
Acute onset of mandibular nerve paralysis
Bilateral paralysis - dropped jaw
OR unilateral paralysis - masticatory muscle atrophy
Clinical signs for bilateral trigeminal neuropathy
Dropped jaw, unable to close mouth, drooling, horners syndrome or facial hypalgesia
Etiologies for bilateral trigeminal neuropathy
Idiopathic trigeminal neuropathy/neuritis**
Polyneuropathy
Hematopoietic neoplasia -RARE
Diagnosing /treating idiopathic trigeminal neuropathy
MRI are usually not helpful for diagnosis
Treat by taping muzzle shut
Steroid therapy has no affective clinical course
Will spontaneously resolve in 2-3 weeks
Etiology for unilateral trigeminal neuropathy
Nerve sheath tumor
Meningiomas
Lymphoma
Polyneuropathies
Diagnosing unilateral trigeminal neuropathy
MRI of head recommended - aggressive DX
Lobular mass lesions extending into brainstem ipsilateral to muscle atrophy
Facial paralysis etiologies
Idiopathic - dogs 75%, cats - rare
Otitis media/interna
Otic neoplasms
Polyneuropathy - hypothyroidism
Intracranial lesions- associated with other deficits
clinical signs for facial paralysis
Acute**
Lip droop
Absent menace
Absent palpebral reflex
Drooling on affected side
Widened palpebral fissure
+/- exposure keratitis
Idiopathic diseases for facial paralysis
60% initially unilateral
Rule out other etiologies
Recovery in 3-6 weeks
Contralateral signs may develop in future
Vestibular neuropathy etiologies
Otitis media/interna - 50% of cases
Idiopathic
Otic neoplasms
Trauma
Polyneuropathy - hypothyroidism
Ototoxicity - rare
PVL or CVL
Head tilt
PVL - ipsilateral to lesion
CVL - ipsilateral or contralateral to lesion
PVL or CVL
Pathological nystagmus
PVL - usually horizontal or rotary, fast phase away from lesion
CVL - horizontal, rotary, vertical, direction changes w head position
PVL or CVL
Postural reactions
PVL - normal
CVL - deficits ipsilateral to lesion
PVL or CVL
CN deficits
PVL - +/- ipsilateral CN VII
CVL - +/- ipsilateral CN V-XII
PVL or CVL
Horner syndrome
PVL - +/-
CVL - +/-
PVL or CVL
Consciousness
PVL - normal
CVL - normal to comatose
Clinical signs for vestibular neuritis
Acute peripheral vestibular signs
Head tilt, vestibular ataxia, pathological nystagmus
Signs may be bilateral in 25% of cats
Idiopathic disease for vestibular neuritis
Geriatric disease in dogs (median 12 years)
Rule out other etiologies (middle ear disease)
Recovery in 2-4 weeks
May recur in the future
Steroid responsive meningitis arteritis
SRMA
Systemic immune mediated disease w inflammation predominately affecting leptomeninges of cervical spinal cord & associated necrotizing fibroid arteritis
SRMA cause
Most common cause of inflammatory SC disease in dogs
Affects young 6-18m, large breed dogs - beagle, boxer, Bernese, Weimaraner
No environmental, drug related, neoplastic, infectious triggers
Acute form of SRMA
Acute form - signs present <1m
Lethargy, hyporexia, fever, cervical hyperpathia/ridigity, normal neuro exam
Chronic form of SRMA
Clinical signs present for >1 months and be cyclic
Persistent and relapsing episodes of hyperpathia anywhere along vertebral column w ataxia or paresis or rarely a multifocal brain and SC presentation
Diagnosing SRMA
NO Definitive antemortem diagnostic
Presumptive diagnosis based on clinical /lab findings
Non degenerative neutrophilia pleocytosis in CSF
Elevated serum IgA
MRI may show thickened /contrast enhancing meninges
