Neuro exam / diagnostics Flashcards
What EEG waves are normal
- Beta-waves ->alert wakefulness or REM sleep
- Alpha-waves -> quiet wakefulness
- Theta-waves and deta-waves -> slow wave sleep
Where can the lesion be in Horner’s syndrome
- Cervical spine
- T1-T3 spine
- Cranial thoracic sympathetic trunk
- Cervical vago-sympathetic trunk
- Cranial cervical ganglion
- Post-ganglionic (cervical sympathetic nerve) - passes through middle ear cavity
Sections of the neuro exam
- Mentation / general observation
- Gait / posture
- Cranial nerves
- Segmental reflexes
- Proprioceptive placing
- Palpation
- Nociception
Where can a lesion causing altered mentation be located
- Brainstem (ascendning reticular activating system)
- Cerebrum (forebrain)
Name 3 postures that can be noticed on neuro exam and say what localization of lesion they indicate + prognosis
- Decerebrate posture: opisthotonus with extensor rigidity of 4 limbs and comatose patient
-> severe midbrain lesion
Very poor prognosis - Decerebellate posture: opisthotonus with extensor rigidity of front limbs and flexed pelvic limbs. normal consciousness
-> cerebellum lesion
No effect on prognosis - Schiff-Sherington posture: hyperextension of forelimbs with pelvic limbs paresis
-> T3-L7 lesion
No effect on prognosis
What findings indicate central vestibular disease vs peripheral? What structures can be affected in peripheral vs. central
- Cranial nerve deficits other than ipsilateral CN VII
- Proprioceptive deficits
- Paresis
- Cerebellar deficits
- Vertical or rotatory nystagmus
- Altered mentation
(- Ipsilateral strabismus, CN VII, and ataxia also present with peripheral disease) - Peripheral = semicircular canals or CN VIII (except cell body)
- Central = CN VIII nuclei in brainstem (pons / rostral medulla), cerebellum
What is the pathway of the menace response
Afferent: ipsilateral CN II, contralateral thalamus, contralateral occipital cortex
Efferent: Contralateral motor cortex, ipsilateral cerebellum, ipsilateral CN VII
On which side is the lesion of a patient circling to the right if it is a vestibular vs cerebral lesion
Lesion on the right in both cases
(Circle towards lesion) unless paradoxical with cerebellar lesion
Where can a lesion be located in case of proprioceptive placing deficits (indicate ipsilateral / contralateral)
- Peripheral nerves including cell bodies / intumescence (ipsi)
- Spinal cord (ipsi)
- Brainstem (ipsi)
- Cerebrum (contra)
A dog was HBC and is presented non-ambulatory. Mentation and cranial nerves are normal. Thoracic limbs are normal. There is severe diffuse back pain. There is bilateral paresis of the pelvic limbs and absent withdrawal reflexes in the pelvic limbs and absent perineal reflex. Where is the lesion?
- Lumbar intumescence L4-S3
- OR T3-L3 with spinal shock ->need to reassess reflexes in time
What are the pelvic limb reflexes and what segments do they evaluate
- Patellar reflex = femoral nerve -> L4-L6
- Gastrocnemius reflex = sciatic nerve -> L6-S1
- Perineal reflex = pudendal nerve -> S1-S3
- Withdrawal = mostly sciatic (L6-S1) with some femoral (L4-L6) for hip flexion
What are criteria for brain death
- Clinical findings: coma, apnea, no brainstem reflexes
- BAER (= brainstem auditory evoked response) if patient is not deaf and has no middle or external ear disease -> no waveforms or presence of early waveforms but no later waveforms
- EEG -> inactivity or burst-suppression
List contra-indications to CSF tap
- Acute TBI
- Coagulopathy
- Progressive intracranial hypertension
- Atlantoaxial luxation or cranial cervical fracture / luxation
- Brain MRI findings showing diffuse edema / swelling, acute tentorial or foraminal brain herniation
What are possible sites for CSF tap (exact name)? If sampling from multiple sites, which one should be tapped first
- Cerebellomedullary cistern = cisterna magna
- Lumbar cistern
- Lateral ventricle
Always start with caudal sites (lumbar then cisternal) to avoid blood contamination since CSF flow is rostral to caudal
What are the landmarks for a cisternal CSF tap
- Halfway between occipital protuberance and spinous process of C2 (just cranial to dorsal arch of C1) on midline
- OR center of the triangle formed by the occiput and the wings of C1
What volume of CSF can be safely collected
1-2 mL in cats and small dogs
Up to 6 mL in large dogs
Take less if increased intracranial pressure to prevent sudden drop in CSF pressure and brain herniation
What are indications for a lumbar CSF tap (vs cisternal)
- Disease of the caudal cervical, thoracolumbar, or sacral spinal cord
- Ascending lower motor neuron disease
- Patients who cannot undergo GA
- Patients with increased intracranial pressure
What are the normal WBC count and proteins in CSF
< 3 WBC/uL in cisternal, < 5 WBC/uL in lumbar
< 25 mg/dL in cisternal, < 35 mg/dL in lumbar
What are the most common causes for the following CSF findings:
- mild mononuclear pleocytosis
- moderate / marked neutrophilic pleocytosis
- moderate / marked mononuclear pleocytosis
- marked eosinophilic pleocytosis
- mixed pleocytosis
- albuminocytological dissociation
- Mild mononuclear pleocytosis: inflammation -> viral / rickettsial or non-infectious inflammatory disease, IVDD
- Moderate / marked neutrophilic pleocytosis: infectious / inflammatory -> bacterial meningoencephalitis, SRMA, FIP
- Moderate / marked mononuclear pleocytosis: granulomatous meningoencephalitis, breed-related necrotizing encephalitis, lymphoma
- Marked eosinophilic pleocytosis: parasitic migration (Angiostrongylus, Cuterebra), fungal, eosinophilic meningitis
- Mixed pleocytosis: fungal, protozoal infection, treated infectious / inflammatory condition, CNS necrosis
- Albuminocytological dissociation (normal nucleated cell count with high proteins): non-specific, includes compressive / degenerative diseases
What is assessed with the nasal septum response
- Ophthalmic branch of CN V
- Cortical integration
- CN VII
What are 2 benefits of EEG in seizure management
- Identification of non-convulsive status epilepticus
- Differentiation between paroxysmal episodes and seizures
Where is the lesion in paradoxical vestibular disease? Describe neuro deficits and their side
Cerebellum
- Head tilt and circling away from the lesion (due to decreased inhibition of vestibular system on the side of the lesion)
- Pathologic nystagmus with rapid phase towards the lesion
(“paradoxical” vestibular signs) - Ipsilateral proprioceptive deficits
- Cerebellar ataxia (ipsilateral hypermetry) + vestibular ataxia
+/- intention tremors
+/- menace response deficit
Describe the modified Glasgow Coma Scale
See picture
How to interpret miosis / mydriasis
Assuming the absence of ophthalmic and CN II injury:
- Mydriasis = midbrain lesion or CN III lesion (ipsilateral)
- Miosis = severe brainstem lesion or Horner syndrome (sympathetic pathway)
- Severe bilateral miosis = acute extensive brain disturbance (decreased inhibition of CN III)
- Severe unresponsive bilateral mydriasis = suspect brain herniation, grave prognosis
(otherwise changes can be secondary to corneal ulcer, uveitis, atropine, iris degeneration, blindness of any cause, etc)
