Investigations in Neurosurgery

1. Investigations in Neurosurgery Dr. Ari Sami Neurosurgeon College of Medicine University of Sulaimani

2. 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

3. 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

5. 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)

6. Magnetic Resonance Imaging (MRI)

8. 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

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

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

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

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

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

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

15. 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.

16. Radionuclide imaging • Positron emission tomography (PET): • Utilises positron-emitting isotopes bound to compounds of biological interest

17. 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

18. Myelography

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