Disorders of Cranial Nerves Flashcards
The cranial nerve signs from bilateral CN II indicate the lesson is located where
Midbrain
A combination of cranial nerve signs from CN III, IV, VI indicate the lesion is where
Superior orbital fissure
A combination of cranial nerve signs from CN VI + VII indicate the lesion is where
Pons
A combination of cranial nerve signs from CN VI + VIII indicate the lesion is where
Cerebellopontine angle
What does an unusual combination go cranial nerves potentially suggest
Chronic or malignant meningitis
What does pure motor cranial nerve signs potentially suggest
Myasthenia gravis
- chronic autoimmune neuromuscular disease
What is the symptomss of myasthenia gravis
droopy eyelids
double vision
difficulty making facial expressions
problems with chewing anddifficulty swallowing
slurred speech
weak arms, legs or neck
shortness of breathand occasionally serious breathing difficulties
Wha are cranial nerve signs that don’t necessarily imply a cranial nerve lesion
eye movement disorders
facial weakness,
difficulty swallowing after a stroke
double vision in myasthenia
thyroid eye disease
What are the potentially sites where cranial nerves can be damaged
Within the brain
Crossing subarachnoid space
Outside the skull
How can cranial nerves be damaged within the brain
Ischaemia
Tumour
How can cranial nerves be damaged crossing sub arachnoid space
Meningits
What is an example of how cranial never can be damaged outside the skull
base of skull tumours arising in nasopharynx
What is optic neurtis
Demyelination within the optic nerve (CN II)
What is optic neuritis associated with
Multiple sclerosis
What is the signs and symptoms of optic neuritis
monocular visual loss
pain on eye movement
reduced visual acuity
reduced colour vision
optic disc may be swollen
What has control over pupil constriction
Parasympathetic system
What has control over pupil dilation
Sympathetic system
What is the potential causes of small pupils,
Old age Bright light “Miotic” eye drops Opiate overdose Horner’s Syndrome
What is the potential causes of dilated pupils
Youth Dim lighting Anxiety, excitement “Mydriatic” eye drops Amphetamine, cocaine overdose Third nerve palsy Brain death
Loss of parasympathetic and sympathetic input has what affect on the pupil
Parasympathetic - Fixed dilated pupil
Sympathetic - constricted pupil
What is a common cause of parasympathetic input loss to the pupil
Complete third nerve palsy (CN III, oculomotor)
What is the two causes of third nerve palsy
Microvascular - never cant function due to lack of blood supply
Compressive
What are two examples of microvascular third nerve palsy
Hypertension
Diabetes
What are two examples of compressive third nerve palsy
Posterior communicating artery aneurysm
Raised ICP
