Neuro Shorts Flashcards
What are saccades?
Small, fast movements of the eyes
Which phase of nystagmus is pathological?
Slow phase
Pattern of cerebellar nystagmus
Unilateral or bilateral, causes eye to drift back (slow phase) to centre, with fast phase in direction of gaze. Also called gaze-evoked nystagmus
What is Alexander’s law?
Phenomenon in which the spontaneous nystagmus of a patient with a vestibular lesion is more intense when the patient looks in the quick-phase than in the slow-phase direction.
Pattern of peripheral vestibular nystagmus
Unidirection, frequently horizontal although sometimes tortional, follows ALexander’s law
Causes of monocular nystagmus
CN III, IV, or VI palsy
INO
What is Bell’s phenomenon?
With ipsilateral 7th nerve palsy, eye on side of the lesion may roll superiorly with the corneal stimulus
Causes of Horner’s syndrome
- Carcinoma of lung apex
- Neck - thyroid malignancy, trauma
- Carotid arterial lesion - aneurysm or dissection, tumour, cluster headache
- Brain stem lesions - vascular disease (esp lateral medullary syndrome), syringobulbia, tumour
- Retro-orbital lesions
- Syringomyelia (rare)
Causes of bilateral anosmia
- URTI
- Meningioma of olfactory groove (late)
- Ethmoid tumour
- Head trauma (including cribriform plate fracture)
- Meningitis
- Hydrocephalus
- Congenital - Kallmann’s
Causes of unilateral anosmia
- Meningioma of olfactory groove (early)
2. Head trauma
Causes of absent light reflex but in tact accommodation reflex
- Midbrain lesion (e.g. Argyll Robertson pupil)
- Ciliary ganglion lesion (e.g. Adie’s pupil)
- Parinaud’s syndrome
- Bilateral anterior visual pathway lesions (bilateral afferent pupil deficits)
Causes of absent convergence but intact light reflex
- Cortical lesion (e.g. cortical blindness)
2. Midbrain lesions (rare)
What is one and a half syndrome?
- Horizontal gaze palsy (both eyes unable to look ipsilateral to side of lesion)
- INO
- Means only contralateral eye can ABduct (with nystagmus)
Location of lesion causing upper quadrant homonymous hemianopia
Temporal lobe
Location of lesion causing lower quadrant homonymous hemianopia
Parietal lobe
Causes of pupillary constriction:
- Horner’s syndrome
- Argyll Robertson pupil
- Pontine lesion (often bilateral, but reactive to light)
- Narcotics
- Pilocarpine drops
- Old age
Causes of pupillary dilatation
- Mydratics, atropine poisoning, cocaine
- 3rd nerve lesion
- Adie’s pupil
- Iridectomy, lens implant, iritis
- Post-trauma,
- Congenital
Sign’s of Adie’s syndrome
- Dilated pupil
- Decreased or absent reaction to light (direct and consensual)
- Slow or incomplete reaction to accommodation with slow dilation afterwards
- Decreased tendon reflexes
- Patients are commonly young women
Causes of Argyll Robertson pupil
- Syphilis
- Diabetes
- Alcoholic midbrain degeneration (rare)
- Other midbrain lesions
Signs of Argyll Robertson pupil
- Small, irregular, unequal pupil
- No reaction to light
- Prompt reaction to accommodation
- If tabes associated, decreased reflexes
Causes of optic neuropathy
- Multiple sclerosis
- Toxic (ethambutol, chloroquine, nicotine, alcohol)
- Metabolic - B12 def.
- Ischaemia (DM, temporal arteritis, atheroma)
- Familial - Leber’s disease
- Infective - infection mononucleosis
Causes of cataract
- Old age
- Endocrine - DM, steroids
- Hereditary or congenital - dystrophia myotonica, Refsum disease
- Ocular disease - glaucoma
- Irradiation
- Trauma
Causes of ptosis with normal pupils:
- Senile ptosis (common)
- Myotonic dystrophy
- Fascioscapulohumeral dystrophy
- Ocular myopathy e.g. mitochondiral myopathy
- Thyrotoxic myopathy
- Myasthenia gravis
- Botulism, snake bite
- Congenital
- Fatigue
Causes of ptosis with constricted pupils:
- Horner’s
2. Tabes dorsalis