E3: Neuro Diagnostics Flashcards
What is an EEG?
-A safe and painless recording of the cortical electrical activity
What are the indications to get an EEG?
- Seizure disorders, may be a normal EEG because seizures are episodic events
- Metabolic encephelopathy: Distinguish from generalized slowing
- Distinguish between cortical and subcortical
If a patient is having a seizure, what will you see on EEG?
Epileptiform activity
If a patient has a tumor, infarct, or scar tissue, what might you see on EEG?
Focal discharges/spikes consistent with focal problem
If a patient has encephelopathy or anoxia, what might you see on EEG?
Generalized changes/slowing consistent with metabolic disorders
What is an electromyogram (EMG)?
- A clinical exam of the electrical activity of muscle fibers
- defines location of problems affecting peripheral nerves and differentiates primary muscle conditions from muscle weakness cause by neurological disorders
What are the indications to get an EMG?
- Lower motor neuron disease: ALS
- NMJ disease: Myasthenia gravis
- Muscle disease: myopathy
- Peripheral nerve disorders: carpal tunnel, peripheral neuropathies
If a patient has Myasthenia gravis, what might their EMG show?
Fatigability
If a patient has myopathy, what might their EMG show?
EMG consistent with decreased amplitude of motor response
What are nerve conduction studies used for?
- Used to assess the rate of conduction and the amplitude of response of peripheral nerves, used in conjunction with EMG
- Tests how well and how fast nerves can send electrical signals
What are the indications for nerve conduction studies?
- To differentiate between primary nerve and muscle disorders
- To differentiate lower motor neuron diseases from peripheral neuropathy
If a patient has spondylolisthesis, what should you order to evaluate for degree of instability?
Flexion and extension Lumbar XR
What is first line to evaluate for spinal fractures with or without associated dislocations?
XR
What are the indications for a skull XR?
Trauma, metabolic disease, or malignancy
What are the indications for a CT?
- LOC
- Persistent neurologic dysfunction
- persistent vomiting
- GCS <8 or deteriorating
- Retrograde or anterograde amnesia
- Post traumatic seizures
If a patient has a lens shaped bleed on CT, what should you be concerned about?
Epidural hematoma
If a patient has a crescent shaped bleed on CT, what should you be concerned about?
Subdural hematoma
What must you do before giving thrombolytic medications for a stroke?
-Non contrast head CT to rule out hemorrhagic stroke
What are the indications for MRI?
Tumors, vascular disease, inflammation/infection, MS, degenerative disease
What is the difference between a T1 and T2 MRI?
T1: Reflects uptake of magnetic energy, better for normal anatomy. Fluid is dark
T2: Reflects release of magnetic energy, better for pathology. Fluid is white.
What is the study of choice for brain tumors?
MRI with gadolinium
What is the most sensitive test when you suspect an acute ischemic stroke of the brain and/or spinal cord?
Diffusion MR
What is a diffusion MRI?
Measures the microscopic motion of water
What might you see on MRI if the patient has MS?
Periventricular plaques are common
What is the recommended initial study for a TIA/CVA?
CT is recommended initially, especially prior to anticoagulation. If negative, can get MRI.
What is the recommended study for new onset seizures?
CT
What are the indications for MRI spine?
- Radiculopathy
- high impact trauma
- new or progressive deficit
- suspected tumor or infection
- neurogenic claudication
- New onset of back pain in a patient with cancer
What is a myelography?
-Detects spinal cord pathology/compression, such as herniated discs or spinal stenosis
When is an LP contraindicated?
Papilledema or increased ICP
