Neurologic procedures Flashcards
What spinal level do you perform a lumbar puncture?
L4-L5
Below L2 which is the end of the spinal cord
What should the CSF pressure normally be?
Less than 25-30 cm
What should you do before performing a spinal tap?
CT scan… unless meningitis is suspected
What needle do you use for lumbar puncture?
short bevel
What is considered low spinal pressure and what are some causes?
Below 7 cm
- Hypoproduction
- Distal to occlusion
- Spinal fluid leak
- Spinal cord tumor
What is considered high spinal pressure and what are some causes?
Above 25-30
- Hyperproduction
- Proximal to occlusion
- Malabsorption of spinal fluid
- Obesity- pseudo tumor cerebri
Xanthochromic
The color of CSF due to old blood pigments… subarachnoid hemorrhage
At what point will CSF become cloudy?
If greater than 200 WBC or 400 RBC
Elevated neutrophils means?
Bacterial infection
Elevated lymphocytes means?
Viral infection
Elevated monocytes/macrophages means?
Chronic condition
Things measured in spinal fluid analysis?
Glucose- CSF lags one hour behind blood glucose, never lower than 80% of blood glucose)
Protein
Culture and sensitivity
Special tests (oligoclonal bands)
What is the epidural space?
A potential space that contains no fluid or blood- only access to the nerve roots and disc material
It is accessible to nerve roots- medications can remain outside the spinal canal
How does EEG brain maping work?
Helps locate focuses of function or dysfunction by converting digitial signals to color and 3D images
When are x-rays most useful?
To screen for fracture
- Want to see all 7 cervical vertebrae plus T1… follow lines all the way down
How does a CT scan work?
Gives a 3D view of the body- rotates an x-ray beam around the pt, imaging the body in a series of slices
Adding cameras adds more slices, heat, and radiation
More radiation is = to more than 100 chest xrays
When do you use a CT?
To view
- Hemorrhages
- Spinal fractures
- Kidney stones
Needs IV contrast
- Abscess
- Tumor
How does a PET scan work
Inject FDG into patient –> metabolism of FDG in the glucose pathway gives off positron + gamma radiation
Cancer cells use more glucose than normal cells and emit more gamma radiation
What shows up the most on MRI?
Things with a lot of water
How does an MRI work?
Protons wobble in alignment with magnetic fields of varying intensity, frequency of wobble is proportionate to strength of individual magnetic field
A brief radio signal whose soundwaves frequency equals the frequency of wobble of certain protons, knocks those protons out of alignment
When radio signal ceases, protons snap back into alignment with magnetic field, emitting a radio signal of their own that announces the presence of a specific tissue
How do T2 weighted images appear?
CSF is bright
How do T1 weighted images appear?
CSF is dark
Fluid-Attenuated Inversion Recovery
T2-weighted image with spinal fluid blanked out
- Shows edema and gliosis to be hyperintense
When is an MRI useful?
- Tumor
- Soft tissue surrounded by bone
- Sclerotic lesions in brain tissue (M.S.)
- Vascular lesions
- When there is edema or excess fluid (meningitis)
When is a spinal tap useful?
- Meningitis
- Degenerative neurologic conditions (MS, ALS)
- Diseases suspected to alter spinal fluid pressure or circulation
Where is the lesions if presenting with bitemporal hemianopia?
Around the pituitary gland
Causes for when a pupil doesn’t react to light
- Blindness
- Optic neuritis (sometimes due to MS)
- Optic nerve tumor
Causes for when a pupil remains dilated
Adie’s pupil
A u/l dilated pupil may be a CN III due to
- herniation of the ipsilateral cerebral hemisphere
- strokes, diabetes, migraine
If due to ischemia inside the brain- pupil is spared
If due to lesions outside the brain (tumor, herniation)- pupil is not spared
Ptosis is injury to what muscle?
Levator palpebrae superioris
Horner’s Syndrome
Due to damage of the sympathetic nervous system.
Ptosis- weakness in Mueller’s muscle
Miosis
Anhydrosis
How do you test CN IV?
Have patient look down and in
Serves the c/l superior oblique muscle
CN VI serves which muscle?
ipsilateral lateral rectus muscle
What does CN VII supply
Motor- muscles of facial expression
- Taste of anterior tongue
- Lacrimation and salivation
Central vs peripheral CN VII palsy
Peripheral- hits the facial nerve after it has left the pons
- BOTH the upper and lower facial muscles on that side are impaired
- -> Bell’s Palsy
Central- lesion is in the pons or upper brain stem
- ONLY the lower facial muscles are impaired
- May be bc the lower facial muscles receive innervation from BOTH SIDES of the motor strip in the frontal lobes
MUST KNOW
Double cross of the cerebellum
Cerebellum coordinates movements of the SAME SIDE because the “double cross” of cerebellar efferents-
cross over in the brainstem (traveling to c/l thalamus and motor cortex) and then cross again in the medulla
MUST KNOW
Therefore, L cerebellum problems effects your L leg
Why do strokes or hemorrhages that extend to one cerebral hemisphere cause rapid death?
Brain stem is damage and blocks the fourth ventricles CSF flow
What does Romberg test?
Posterior columns and cerebellum
What 3 functions does upright posture require?
- Vision
- Cerebellum
- Posterior columns
Grading of strength
Severe weakness 0/5- absolutely no movement in a group 1/5- minimal, or "flicker" of movement 2/5- minimal horizontal movement, but no movement against gravity 3/5- some movement against gravity
Moderate weakness
4/5- moderate strength against gravity and some resistance
5/5- normal contraction
Quadriplegia
Disease of the upper or mid cervical spine, or both of the corticospinal tracts of the brain stem
Hemiplegia
Disease of one cerebral hemisphere or one side of the brainstem along the corticospinal tract
Paraplegia
Disease of the spinal cord in the thoracic or high lumbar regions
Causes of weakness of one arm
Cervical spine disease or the brachial plexus, or some strokes
Causes of weakness of one leg
Lumbar spine disease or the lumbar sacral plexus
- Rarely a stroke- anterior cerebral artery infarct
Grading of DTRs
0- no reflex 1- diminished reflex 2- average reflex 3- increased reflex, but only one beat 4- increased reflex with clonus- 2 or more beats
A reflex of 0 is usually pathologic, but a reflex of 4 is always pathologic
Normal and abnormal plantar reflex
Normal- Flexion of the big toe
Abnormal- extensions of the big toe –> Babinski sign
Upper motor neuron signs
Problem in brain or spinal cord
- Increased reflexes, spasticity, only delyated atrophy of muscles, Babinski signs
Lower motor neuron signs
Problem in motor neuron, NMJ, muscle iteself
- Decreased reflexes, atrophy within weeks, sometimes fasciculations, no Babinski signs
Decreased DTRs can be caused by?
Diabetes mellitus Hypothyroidism vitamin B12 deficiency Exposure to heavy metals or some organic chemicals Auto immune disease
Increased DTRs can be caused by?
Lesions of the corticospinal tracts, especially in the spinal cord or brain stem
Hemiplegic gait
With circumduction- inability to bring the leg all the way in
Spastic gait
Limited ability to bend at the hips and knees
Fenistating gait
Slow with the first steps,t then faster and faster, and out of control- in Parkinson’s disease
