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

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: –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 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):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.

Radionuclide imaging Positron emission tomography (PET):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 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