DM Neuro

Indications of LP

infection, bleeding (SAH), CSF leak

Diagnose or exclude bacterial, viral, fungal, and parasitic infections of the CNS

r/o SAH

demyelinating dz- MS, Guillain-Barre

CI of LP

Skin or soft tissue infection at puncture site
Acute spinal cord or head trauma
Uncorrected severe coagulopathy
Brain shift secondary to space occupying lesions or edema

When can a CT scan should be obtained prior to LP?

1. CT scan of the head before performing lumbar puncture to identify intracranial abnormalities (such as inc. ICP or mass lesion) and thus avoid the risk of brain herniation

2. Suspected meningitis IF:

   1. Pt has grossly AMS

   2. Active and recent seizures

   3. Focal neurological signs

   4. papilledema

How does LP work?

CT prior IF suspected meningitis (AMS, sz, neuro signs, papilledema) or high risk for developing herniation

Complications of LP

Local discomfort
Radicular, back pain
Spinal hematoma
Neurologic symptoms
Post-lumbar puncture headache

How does CT Scan work?

direct cross-sectional imaging of the brain and spine from thin x-ray beams of radiation which form sagittal, oblique, coronal reformations and 3D images

Indication of CT Scan

head or spinal trauma, headache, cerebral infarct, elevated ICP or potential mass, intracranial calcifications, bone or temporal bone lesions, post-op for spine, degen spinal disease, if MRI not obtainable

CI for CT

Children or PGY for iodine contrast, shellfish allergy, very obese (over 400lb)

Pros of CT

-Cheap
-Quick

Cons of CT

-Radiation expo
-Poor spatial and soft tissue resolution within the spinal canal

What structures enhance with contrast for CT?

-Venous sinuses

-Choroid plexus

-Pituitary gland and stalk

Structures that may show up as artifact on CT?

-Dental filling

-Aneurysm clip

-Bullet

How does MRI work?

placed into a strong magnetic field > radiofrequency pulse stimulates a patients hydrogen protons

What are the indications of MRI?

TOC for detecting and staging intracranial and spinal cord abnormalities

BRAIN: Stroke, Chronic HA, Seizure, Tumor, Infection, Trauma, Demyelinating disease, Vascular malformation, Aneurysms, Extracranial carotid artery disease, Vasculitis, Leptomeningeal dz, Pituitary mass, congenital malform
SPINE: degenerative spinal disease, spinal infection, congenital abnorm, scoliosis, Tumors, Trauma

CI for MRI

No contrast PGY (but OK for lactation)

ANYTHING METAL!
-intracardiac devices, cochlear implant, bone growth or SC stimulator, aneurysm clips, ocular implants, metallic foreign body, tattooed eyeliner

Pros of MRI

-More sensitive than CT (superior contrast and soft tissue resolution)
-Lg # of sequences inc sensitivity and specificity
-Don't have to manipulate patient’s position
-No radiation
-Gadolinium contrast safer
-White matter lesions visible
-DWI Cerebral infarctions

Cons of MRI

-Less sensitive to CT in detecting calcification in lesions or evaluation of cortical bone
-Slower
-Claustrophobia
-Magnetic field dangers

What is the contrast in CT?

iodine IV

What is the contrast in MRI?

IV chelated gadolinium (no in PGY but safe in lactating women)

MRI is less sensitive than CT in detecting what?

detecting calcification in lesions or evaluation of cortical bone

MRI is more sensitive than CT in detecting what?

superior contrast and soft tissue resolution

How does myelogram work?

Modified plain-film technique w/ water-soluble contrast in subarachnoid space via L = forms mult plain films in diff projections

Indication of myelogram

Better views SC and spinal roots, ID dural tears, deformities in SAS, lesions, suspected meningeal or arachnoid cysts, CSF fistulas, CSF leaks, MRI not obtainable, degen spinal dz

CI of myelogram

Inc ICP, spinal block, h/o allergic rxn to intrathecal contrast

Pros of myelogram

-some providers prefer anatomic display and spatial resolution

Cons of myelogram

-invasive
-contrast agent is relatively neurotoxic
-possible iatrogenic infection or LP related hemorrhage

What scan is obtained after myelogram?

CT myelogram

Complications of myelogram

-headache (Postural HA due to CSF leak)

-N/V

-Vasovagal syncope (during LP)

-Hearing Loss

-Spinal cord puncture

How does cerebral arteriography work?

Small catheter placed into BV > direct catheter to location desired > Inject contrast into vessel and films obtained

Indication of cerebral arteriography

Intra/extracranial and spinal vascular lesions, SAH or parenchymal hemorrhage, small vessel pathology (vasculitis), vascular malformations/aneurysms

CI of cerebral arteriography

Stroke, Ionic contrast material can be
neurotoxic

Pros of cerebral arteriography

-High spatial resolution

Cons of cerebral arteriography

Risk of morbidity and mortality
-Long /uncomfortable
-Possible conscious sedation
-Possible hospitalization for post-observation

Indic of skull and spinal x-ray

Foreign bodies, Spinal alignment and stability, Spinal fx infections, and metastases, spinal anomalies, degen disk disease, bone lesions, ventriculoperitoneal shunt

Pros of skull and spinal x-ray

-Inexpensive
-Easy to obtain
- Portable machine to bedsides

Cons of skull and spinal x-ray

-Overlapping structures obscure pathology
-No soft tissue information

How does nuclear medicine brain scan work?

Uses IV admin radiopharmaceuticals (combo of radioisotopes and pharmaceutical carrier) = that concentrate in tissues (M/C = Technitium-99m linked linked to pharm = Tc-99 pertechnetate)

Indic of nuclear medicine brain scan

-T-99 P = confirm brain death
-Indium-111 DTPA injected in SAS = CSF leaks via basal skull defects and fx
-Hydrocephalus

How does SPECT work?

Nuclear medicine study (using technetium-99m) performed & gamma camera = 2D images made into 3D dataset > highlights metabolically active areas with inc BF or vascular regions w/ dec cerebral BF

Indic of SPECT

Cerebral aneurysms and other vascular malformations, Surgical planning for brain tumors, Stroke, Epilepsy, Dementia

Pros of SPECT

- Less exposure to radiation (compared to CT and fluoroscopy)

Cons of SPECT

- source of radiation exposure to others utilizing nuclear

How does PET work?

Nuclear medicine study on molecular level = 3D images of body’s biochemical and meta processes w/ fluorine 18-labeled deoxyglucose (F-18 FDG) > determines brain activity , can cross BBB via glucose

Indic of PET

dx brain tumors, discriminate active tumor from radiation necrosis, help bx aggressive areas in lesions, diff b/t recurrent tumor from post-therapy change, localize epileptic foci in temporal lobe

How does CSF analysis work?

Collected from LP, Looks at:
-CSF pressure
-CSF chemistry: glucose and protein
-CSF cell count/types: RBC, WBC, cytology, flow cytometry
-CSF microbio: cultures, polymerase chain reaction (PCR), and antib

For CSF analysis, glucose should be?

should be 60% (dec (hypoglycorrhachia) in bacterial, fungal, and tubercular CNS inf (not viral! = CNS hypermetabolism)

For CSF analysis, protein should be?

<50mg/dL (elev in inf or inflam state or obstructed circulation of CSF)

For CSF analysis, WBC should be?

0-5 WBC/mm (inf, inflam, malig)

For CSF analysis, RBC should be?

0-5 RBC/mm (elev if SAH or traumatic LP)

For CSF analysis, lactate should be?

1.2-2.1 mmol/L (diff viral meningitis/encephalitis from bact inf)

For CSF analysis, myelin should be?

<4ng/mL (Marker for demyelination, M/C in M.S. but also CNS trauma, encephalopathies, stroke, and inf)

How does EEG work?

Measures electrical signals from brain via electrodes on the scalp > Voltage fluctuations detected are membrane potentials from brain tissue > Compares voltages recorded from 2 diff brain regions and plot result overtime = Spatial and temporal information about brain activity

Indic of EEG

Confirm dz or classify sz or epilepsy, ID structural, functional, or metabolic abnormality, Dx nonconvulsive status epilepticus or neurologic syndromes, monitor perfusion during carotid endarterectomy

Cons of EEG

Cons:
-may be nonspecific
-Lack sensitivity
-some neuro disorders may = normal EEG
-Normal tracings do not exclude underlying epilepsy

What are complications of MRI?

- gadolinium based contrast linked to development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD)

How EMG/NCS works?

Evaluate function of peripheral nervous system; Typically performed together

EMG = Study of electrical activity of muscle fibers , record muscle activity in resp to prox stim of motor nerve
NCS = electrical activity from N roots, plexus, and periph Ns, neuromusc junc ; Record velocity and amplitude of nerve APs

Indic of EMG/NCS

Evaluate if sx is 2/2 injury in the peripheral nervous system, localize site of injury (Spinal root, nerve, plexus, peripheral nerve, NMJ or muscle), or examine severity and chronicity of injury

CI in EMG/NCS

EMG = caution in those patients on anticoagulation and/or antiplatelet, Skin infection / tissue pathology, Lymphedema
NCS = pts with permanent pacemakers/ internal defibrillators

Pros of EMG/NCS

-relatively safe
-uncomfortable but well tolerated

Purulent sinusitis on CT, what to do?

1. Get an upright occipitomental (Waters) view in those diagnosed with purulent sinusitis on CT

Normal LP pressure

<20 cm H2O

Abnormal LP Pressure

>20 cm H2O

Inc ICP indicates?

1. Tumors, infection, hydrocephalus, and intracranial bleeding can cause increased intracranial and spinal pressure

Dec ICP indicates?

1. hypovolemia (dehydration or shock), chronic leakage of CSF through a previous LP site, or through a nasal sinus fracture with a dura tear

Normal LP fluid should be

clear and colorless

When does xanthochromia in LP occur?

1. occur w/ hyperbilirubinemia, hypercarotenemia, melanoma, or elevated protein levels

Neutrophils are indicative of?

1. is indicative of bacterial meningitis or cerebral abscess

Mononculear leukocytes are indicative of?

viral or tubercular meningitis or encephalitis is suspected.