Neuro investigations Flashcards
What is an EEG
Electroencephalogram- Tests for epilepsy
- 21 Electrodes on scalp
- Impulse from reticular formation>thalamus> pyramidal cells then picked up
- Left odd numbers, even right, letter is F Central T O
- Looks at beta, alpha, theta and delta frequencies
- May have one lead ECG at bottom
- Uses activation techniques during the 20 minutes
What is an EP test?
Evoked potential- Assess silent regions in nerve patients. For MS
What is NCS and EMG
Nerve conduction studies and electromyography
Electromyography
- Recording needle into muscle and looks at the trace
What is IOM
Intraoptive monitoring
What is an MSLT
Multiple sleep latency test- Diagnoses narcolepsy - looks how quick fall into rem sleep, If rem 3 out of 5 then narcolepsy
In EEG what is Beta frequency?
Fastest. Increased in anxiety and drugs
In EEG what is Alpha frequency?
- Prevelent when eyes closed, then goes when eyes open
In EEG what is Theta Frequency?
- Increased in drowsiness, more common in children
In EEG what is Delta Frequency?
Slowest- seen in sleep in young or in adults encephalopathies or vascular issues e.g. dementia, space occupying regions
Which activation techques are used in an EEG?
- Hyperventilation- Used if looking for absent seizures as this triggers then, space occ lesions and temp lobe abnormal
- Photic- Flash light- for juvenile myoclonic epilepsy
- Tactile and auditory- Sees if unconscious patients have cortisol response to stimuli
Treatment for absent seizures
Ethosuxamide or SV
MOA of Ethosuxamide
inhibits NADPH-linked aldehyde reductase necessary for the formation of gamma-hydroxybutyrate, which has been associated with the induction of absence seizures
MOA of Sodium Valproate
inhibit succinic semialdehyde dehydrogenase. This inhibition results in an increase in succinic semialdehyde which acts as an inhibitor of GABA transaminase ultimately reducing GABA metabolism and increasing GABAergic neurotransmission.
What is Landua-Kleffner Syndrome
- Sudden regression in speech then no speech
- Can be mistaken for deafness
- May have seizures with this
- Children 4-8
What would Landua-Kleffner Syndrome EEG look?
Sharp and slow waves
Which nerves do nerve conduction studies look at
- Sensory and motor
If got numbness tingling, weakness e.g PN, carpal tunnel, GB
What does the nerve conduction study look at?
Lactency-Time taken for stimulus to travel (Myelination) Trapping?
Amplitude- Size of the response. the amount of fibres stimulated
What is carpal tunnel syndrome
- Compression of median nerve
- Get pain numbness tingling
- If slowing of nerve (Latency) then its trapped
What does the ulnar nerve supply?
Little finger and half of ring finger
What is cubital tunnel syndrome
- Ulnar nerve trapped at the elbow
What is preipheral neuropathy?
- Longer nerves affected first so feet
What is an EMG
Electromyography
- Recording needle into muscle and looks at the trace
What are the 3 types of evoked potentials
- Visual EP- for MS- Put electrode on scalp, stimulate optic nerve and check time for brain response. Look at latency and amplitude which shows silent regions. P100 should be 100
- Auditory- Headphones on and use clicks- Can be used for MS
- Sensory- Stimulate nerve in arm or leg
All look for silent lesions in MS
