Transcript 1._Investigations_in_Neurosurgery

Investigations in Neurosurgery
Dr. Ari Sami
Neurosurgeon
College of Medicine
University of Sulaimani
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Skull X-rays
Standard views:
– Lateral
– Postero-anterior
– Towne`s (fronto-occipital)
Look for:
– Fractures
– Bone erosion:
focal( pituitary fossa)
–
generalized (Multiple
myeloma)
– Bone hyperostosis:
focal
(Meningioma),
generalized (Paget`s disease)
– Abnormal calcification:
tumors
(meningioma), aneurysmal wall
– Midline shift of pineal body
– Signs of increased intracranial pressure
– Configuration: platybasia, basilar
impression
Computed tomography (CT)
scanning
• A pencil beam of X-ray
traverses the patient's head
and a diametrically opposed
detector measures the extent
of its absorption.
• Determination of absorption
values for multiple small
blocks (voxels)
• Reconstruction of these areas
on a two-dimensional display
(pixels) provides the
characteristic CT scan
appearance
Interpretation of the cranial CT
• Ventricular system: size, position, compression
• Width of cortical sulci and sylvian fissure:
• Skull base and vault: hyperostosis, osteolytic lesion,
remodelling, depressed fracture
• Multiple lesions: tumor, abscesses, granuloma,
infarction, trauma
• Abnormal tissue density:
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Midline shift
Ventricular compression
Obliteration of the basal cisterns, sulci
High density( blood, calcification in tumor or AVM or
hamertoma)
– Low (infarction, tumor, abscess, oedema, encephalitis,
resolving hematoma)
– Mixed (tumor, abscess, AVM, contusion, hemorrahgic
infarct)
Magnetic
Resonance
Imaging (MRI)
Advantages
• Can select any plane, e.g. coronal,
sagittal, oblique.
• No ionizing radiation.
• More sensitive to tissue changes, e.g.
demyelination plaques.
• No bone artifacts, e.g. intracanalicular
acoustic neuroma
Disadvantages
• Limited slice thickness-3mm.
• Bone imaging limited to display of
marrow.
• Claustrophobia.
• Cannot use with pacemaker or
ferromagnetic implant.
MR angiography
• Rapidly flowing
protons can create
different intensities
and by a special
sequence can
demonstrate
vessels, aneurysms,
and AVM
MRI
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Diffusion-weighted MRI
Perfusion-weighted MRI
Functional MRI
MR spectroscopy (N-acetylaspartate,
lactate,ATP, and inorganic phosphate)
Ultrasound
• Extracranial: Doppler, colour
doppler
• Intracranial-transcranial doppler
ultrasound:
– Assessment of intracranial
hemodynamics
– Detection of vasospasm in SAH
Angiography
• DSA: subtraction of a
pre-injection film from
the angiogram
eliminates bone
densities and improves
vessel definition
– Phases:
• Arterial
• Capillary
• Venous
Carotid
vertebral
Interventional angiography
• Embolization
– Particles (ivalon sponge)
– Glue (isobutyl-2-cyanocrylate)
– Balloon (detachable) for CC fistula
– Platinum coils
– Stents
– Angioplasty
Radionuclide imaging
• Single photon emission computed
tomography (SPECT):
– Uses compounds labelled with gammaemitting tracers (ligands) and a rotating
gamma camera is often used for detection
– Detection of early ischemia
– Evaluation of patients with intractable
epilepsy of temporal lobe origin
– Thallium SPECT: differentiate low from
high grade tumors.
Radionuclide imaging
• Positron emission tomography (PET):
– Utilises positron-emitting isotopes bound
to compounds of biological interest
Lumbar puncture
• CSF analysis
• CSF drainage and pressure reduction
• Avoid LP:
– If raised intracranial pressure is suspected
– If platelet count is less than 40 000 and
prothrombin time is less than 50% of
control
Myelography
Others
• EEG
• Evoked potentials:
– Visual
– Auditory
– Somatosensory
• EMG and NCS
• Neuro-otological tests
– auditory system
– vestibular system