Cranial Nerve Disorders Flashcards
Which cranial nerves are for special senses?
I - smell
II - sight
VII, IX, X - taste
VIII - balance/hearing
Which cranial nerves have normal sensory functions?
Mainly V
VII and IX - ear
Which cranial nerves have motor function?
III, IV, VI - eye muscles V - mastication VII - facial expression X - larynx, pharynx XI - SCM, trapezius XII - extrinsic/intrinsic tongue muscles
Which cranial nerves have autonomic function?
III - pupillary conscriction VII - lacrimation VII - salivation (submandibular/sublingual) IX - salivation (parotid) X - thorax/abdominal organs
How can we test each cranial nerve?
I - sense of smell - unilateral/bilateral loss
II - visual acuity, fields, pupillary response, fundoscopy, colour vision
III, IV, VI - ptosis, equal pupils, pupillary response, eye movements
V - sensation, power, corneal reflex, jaw jerk
VII - muscles of facial expression, corneal reflex, taste
VIII - hearing (Rinne’s, Weber’s), Dix-Hallpike, Untenberger’s
IX, X - movement of palate, gag reflex, quality of speech/cough
XI - head turn, shoulder shrug
XII - apperanace, movement/power of tongue
Which reflexes have cranial nerve involvement?
Pupillary light reflex - Afferent II, Efferent III
Corneal reflex - Afferent V, Efferent VII
Jaw jerk - Afferent/Efferent V
Gag reflex - Afferent IX, Efferent X
Where are each cranial nerve nuclei located?
III and IV - midbrain
V, VI, VII - pons
VIII - pontomedullary junction
IX, X, XI, XII - medulla
What are common combinations of cranial nerve signs and why?
Bilateral III - midbrain problem
III, IV, VI - superior orbital fissure problem
VI, VII - pons problem
V, VIII cerebellopontine problem
Unusual combination? - chronic/malignant meningitis
Pure motor signs? - myasthenia gravis
What is optic neuritis? Signs/symptoms?
Demyelination of optic nerve Monocular vision loss Pain on eye movement Reduced visual acuity Reduced colour vision Optic disc may be swollen Often associated with MS
How are pupillary responses controlled?
Parasympathetic
- pupil constriction
- loss of parasympathetic input > fixed, dilated pupil
- e.g. complete CNIII palsy
Sympathetic
- pupillary dilation
- damage anywhere can lead to constricted pupil
What are some causes of dilated pupils?
Youth Dim lighting Anxiety, excitement Mydriatic eye drops Amphetamine, cocaine overdose CNIII palsy Brain death
What are some causes of constricted pupils?
Old age Bright light Miotic eye drops Opiate overdose Horner's syndrome
What are some causes of eye movement disorders?
Can be isolated III, IV, VI palsy or combination
Supranuclear gaze palsy, nystagmus
Isolated III palsy
- microvascular e.g. diabetes, hypertension - painless, pupil spared
- compressive - PCA aneurysm, raised ICP - painful, pupil affected
Isolated VI palsy
- idiopathic
- diabetes
- meningitis
- raised ICP
Nystagmus
- congenital
- serious visual impairment
- peripheral vestibular problem
- central vestibular/brainstem disease
- cerebellar disease
- toxins (medication and alcohol)
What is trigeminal neuralgia? Signs/symptoms? Treatment?
Paroxysmal attacks of lancinating pain Has triggers Common in middle age and older Caused by vascular loop - compression V nerve in posterior fossa Treated medically with carbamazepine Surgical options if medication resistant
What is Bell’s palsy? Signs/Symptoms? Treatment?
Idiopathic VII palsy Unilateral face weakness LMN type Often preceded by pain behind ear Eye closure affected Risk of corneal damage Treated with steroids Usually good recovery
What is vestibular neuronitis?
Sudden onset Disabling vertigo Vomiting Gradual recovery Cause uncertain - viral?
What terms are used to describe problems with speech and swallowing?
Dysarthria - disordered articulation, slurring of speech Dysphagia - difficulty swallowing Both occur in bulbar/pseudobulbar palsy - bulbar = LMN - pseudobulbar = UMN
Dysphonia - an impairment of the voice/difficulty in speaking e.g. hoarseness
What are bulbar and pseudobulbar palsies, and their features?
Pseudobulbar palsy
- bilateral UMN lesions e.g. vascular lesions of both internal capsules - MND
- dysarthria, dysphonia, dysphagia
- spastic, immobile tongue
- brisk jaw jerk
- brisk gag reflex
Bulbar palsy
- bilateral LMN lesions affecting IX-XII
- e.g. MND, polio, tumours, vascular lesions of medulla, syphilis
- wasted, fasciculating tongue
- dysarthria, dysphonia, dysphagia
- beware of feeding these patients
