Investigations in Neurosurgery

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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
• Townes (fronto-occipital)
• Look for
• Fractures
• Bone erosion focal( pituitary fossa)
• generalized (Multiple myeloma)
• Bone hyperostosis focal (Meningioma),
  generalized (Pagets disease)
• Abnormal calcification tumors (meningioma),
  aneurysmal wall
• Midline shift of pineal body
• Signs of increased intracranial pressure
• Configuration platybasia, basilar impression

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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

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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
• 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)

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Magnetic Resonance Imaging (MRI)
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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

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Disadvantages

• Limited slice thickness-3mm.
• Bone imaging limited to display of marrow.
• Claustrophobia.
• Cannot use with pacemaker or ferromagnetic
  implant.

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MR angiography

• Rapidly flowing protons can create different
  intensities and by a special sequence can
  demonstrate vessels, aneurysms, and AVM

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MRI

• Diffusion-weighted MRI
• Perfusion-weighted MRI
• Functional MRI
• MR spectroscopy (N-acetylaspartate, lactate,ATP,
  and inorganic phosphate)

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Ultrasound

• Extracranial Doppler, colour doppler
• Intracranial-transcranial doppler ultrasound
• Assessment of intracranial hemodynamics
• Detection of vasospasm in SAH

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Angiography

• DSA subtraction of a pre-injection film from the
  angiogram eliminates bone densities and improves
  vessel definition
• Phases
• Arterial
• Capillary
• Venous
• Carotid
• vertebral

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Interventional angiography

• Embolization
• Particles (ivalon sponge)
• Glue (isobutyl-2-cyanocrylate)
• Balloon (detachable) for CC fistula
• Platinum coils
• Stents
• Angioplasty

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Radionuclide imaging

• Single photon emission computed tomography
  (SPECT)
• Uses compounds labelled with gamma-emitting
  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.

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Radionuclide imaging

• Positron emission tomography (PET)
• Utilises positron-emitting isotopes bound to
  compounds of biological interest

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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

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Myelography
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Others

• EEG
• Evoked potentials
• Visual
• Auditory
• Somatosensory
• EMG and NCS
• Neuro-otological tests
• auditory system
• vestibular system