Cranial Nerve disorders Flashcards
Discuss trigeminal neurologia
Trigeminal nerve is the sensory supply to the face and the sensory and motor supply to the muscel of mastication
Mechanisms
- Compression of the trigeminal nerve root - most cases of TN are caused by compression of the trigemnial nerve root usually within a few millimetes of entry into the pons. Compression by an aberrant loop of an artery or vein is thought to account for 80-90%
- MS
- Central sensitization.
It is more common in women than in men 2:1- typically between the ages of 50-69 years of age and symptoms occur more frequently on the right side of the face.
Discuss clinical features of TN
Unilateral facial pain - lancinating paroxysms of pain in the lips teeth gums or chin.
-Commonly associated with physical triggers such as chewing brushing shaving washign or touchgin the affected area of the face.
Maxillary and mandibular divisions of the trigeminal nerve are the most commonly affected.
Patients tend to experience the pain in clustered episodes that last a few seconds to several minutes
2-4% of patient with trigeminal neurolagia also have MS and this should be considered in these presentations
Discuss management of TN
Carbamezapine is the treatment of choice – dose starting at 100-200 mg BD and gradually increasing as needed to a max of 1200mg per day.
-ADverse affects : nausea and vomiting, diarrhoea , hyponatraemia rash pruitis drowsiness dizziness or double vision.
For non responders trialling gabapentin or lamotrigine
Both peripheral and central surgical intervention for TN are management options for difficult cases.
Periperhal
- injection and cryotherpay technique
Central
- percutaneous destruction of the TN ganglion - carries risk of corneal anaethesia, oculomtor paresis and masticatory weakness.
-Open include microvascualr decompression of the enrve with or without partial ablation.
Describe Bellspalsy
CN 7 innervates the muscles of facial expression and the muscles of the scalp and external ear in addition to the buccinator, platysma stapedius stylohyoid and posterior belly of the digastric muscles.
The sensory portion of the nerve supplies the anterior two thirds of the toungue with taste
Discuss clinical features of Bells
Characterized by abrupt onset of lower motor neuron paresis that typically develops over 72 hours and can progress during 1-7 days to complete paralysis.
Thought to be caused by viral illness -HSV activation
Other symptoms
- ear pain
- perception of sensory change on the invovled face
- decreased tearing
- abnormally acute hearing
- impairment or preversion of taste
The Nadir of weakness should be reached within 1-2 days of onset of symptoms - worsenign facial weakness beyond the 3 week mark or decelopment of new neurological symptoms warrants MRI
Describe Ramsay hunt syndrome
Characterized by unilateral facial paralysis a herpetiform vesicular eruption and vestibulocochlear dysfunction.
The vesicular eruption may follow the facial paralysis by a few days may occur on the pinna external auditory canal TM soft palate oral cavity face and neck as far as the shoulder.
The pain is considerably more painful then in bells
-worse outcome then bells with lower incident of complete facial recovery and the possibility of sensorineural hearing loss
Discuss the Hosue-Brackmann calssifiection
1: Normal
2: mild dysfunction
a: Gross
-Slight wekaness noticeable on close inspection
-may ahve slight synkinesis
-normal symmetry at rest
B: motion
-Forehead - moderate to good fucntion
Eye- coplete closure with minial effort
Mouth slight asymmetry
3: Moderate dysfunction
a: Gross
-Obvious but no disfiguring difference between the two sides
-Noticeable but not severe synkinesis
-normal symmetry at rest
B: motion
-Forehead - slight to moderate function
Eye- complete closure with effort
Mouth slightly weak with maximal effort
4: moderately severe dysfunction
a: Gross
Obvious weakness and or disfiguring asymmetry
-normal symmetry at rest
B: motion
-Forehead - None
Eye- Incomplete closure
Mouth Assyetrical with max effort
5: severe dysfucntion
a: Gross
Only barley perceptible motion
asymmetry at rest
B: motion
-Forehead - None
Eye- Incomplete closure
Mouth slight movement
DIscuss management of Bells Palsy
Short term couse of oral glucocorticords for everyone
-60-80mg daily for one week
Antiviral therapy - controversial likley better in those treated within 24 hours of symptom onset
-Valacyclovir 1000mg TDS for 7 days for those with severe facial palsy defined as a House-Brackmann grade 4 or higher
Eye care
- Waking hours - artificial tear drops four times a day and up to hourly if needed - can consider protective glasses
- During sleep - Ointment formulation of artifical tears - eye taped shut using waterproof transparent dressing or tape
Treatment of Ramsay hunt is similar to bells although the role for antivirals is more clear
Discuss prognosis of Bells
70% recover fully within 3-6 months and rates of complete recovery increase to approximate 80-85% with appropriate steroid use.
Describe vestibular schwannoma
Formally referred to as acoutsitc neuroma is a rare but important cause of sensorineural hearing loss.
Occurs in middle aged individuals and is usually unilateral
Although histologically benign vestibular schwannoma can cause neurolgoical damage by direct compression on CN 8 and other structures in the CP angle. Cranial nerves 5 and 7 both pass through the cerebellopontine angle
Discuss clinical features of vestibular schwannoma
Asymmetrical sensorineural hearing loss is the hallmark of vestibular schwannoma.
Symptoms such as unilateral tinnitis imbalance headache fulness in the ear otalgia and facial nerve weakness
Treatment is surgical or radition therapy
Discuss diabetic cranial mononeuroapthy
THe most often affected are the extraocular muscles. The oculomotor nerve is the most commonly effected followed by 4 and 5
Opthalmogplegia appears to be closely related to diabetes, facial palsy are less commonly related
Discuss CVT
Women represent 60-75% of cases of CVT - short term mortality can be quite high
Patients with CVT often present with symtpoms of ICH especially headache patients with CVT are more prone to haemorrhaigc infarction and localizing neurological deficits.
Lethargy seizure decreased LOC or mental status changes may be noted.
The average time of symptoms onset to diagnosis is 7 days
MRV or CTV
D-dimer can be used as adjunctive to investigation
Discuss management of CVT
Systemic anticoagulation with low molecular weight heparin or unfractionated heparin even in patients with intracranial haemorrhage on initial imaging
Catheter based thrombolysis has shown promise in the management of CVT
Describe MS
The pathologic manifestation of this inflammatory disease is a demyelination of discrete regions within the CNS with a relative sparing of the axons.
The peak age of onset is 25-30 years old. The incidence in women exceed that in men by a ratio of 1:8
Classic clinical syndrome consists of recurring episodes of neurological symptoms taht rapidly evolve over days and slowly resolve over weeks,
CN dysfunction is common in MS. The most common associated CN abnormality is optic neuritis, which is unilateral syndrome characterized by pain in the eye and a variable degree of VA loss primarily affected the central vision. Within 2 year of an attack of optic neuritis the risk fo MS is approxiamtly 20% within 15 years it is 45-80%
