Investigations in Neurosurgery

Dr. Ari SamiNeurosurgeonCollege of MedicineUniversity 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

Carotidvertebral

Interventional angiography

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

Radionuclide imagingRadionuclide imaging

• Single photon emission computed Single photon emission computed tomography (SPECT):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 imagingRadionuclide imaging

• Positron emission tomography (PET):Positron emission tomography (PET):– Utilises positron-emitting isotopes bound

to compounds of biological interest

Lumbar punctureLumbar 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

OthersOthers

• EEG• Evoked potentials:

– Visual– Auditory– Somatosensory

• EMG and NCS• Neuro-otological tests

– auditory system– vestibular system