INVESTIGATIONS OF NEUROLOGICAL

DISEASES 

Dr. Ra’ed Ahmed MBChB, FIBMSNeurologist

INVESTIGATIONS OF NEUROLOGICAL DISEASES

• history alone will make around 90% of neurological diagnoses.

• Investigation may include assessment of structure (imaging), function (neurophysiology), CSF analysis and others.

A. Neuroimaging

1- Plain skull X-rays are now largely restricted to

the diagnosis of fractures and sinus disease.

Plain X-rays of cervical, thoracic and lumbar spine are useful in the investigation of trauma to vertebrae.

Chest X-ray source of cerebral metastases Tuberculosis & Sarcoidosis

first applications were in neuroradiology

2- Computed tomography (CT(• Tomography is a generic term, formed from the Greek

words tomo (slice) and graph (picture).

• Computed tomography is a diagnostic imaging modality which uses x-rays to image individual cross sectional slices through the body.

• Diagnostic yield is often improved by the use of intravenous contrast and thinner slicing using spiral CT.

CT• Indications : evaluation of an acute change in mental

status, focal neurologic findings, first line investigation for stroke.

• Useful and ideal for cases of ICH, SAH , Trauma with SDH , EDH, Depressed skull fracture.

• Advantages : available, cheap and quick

• Disadvantages : ionising radiation , contrast reactions , invasive (myelography and angiography)

• Limited role in spinal pathology and contraindicated in pregnancy unless performed as an emergency investigation.

systematic approach to interpret CT Brain

• Check patient information and review scan protocol

• Detailed analysis of the images using the mnemonic ‘ABBCS’

‘A’ – Asymmetry ‘B’ – Blood‘B’ – Brain (abnormal density, displacement,

grey/white matter differentiation)‘C’ – CSF spaces – Cisterns, sulci and ventricles

‘S’ – Skull• Finally, extend search pattern to include orbits,

sinuses, oropharynx, ears, etc…

3- MRI: What is it?

Magnetic Resonance ImagingMagnetRadio Frequency = ResonanceImaging

WE ARE MAGNETS!

Really?

How does it work? The Basics

• A magnetic field causes some of the body’s nuclei to behave like tiny compasses and line up

• Then the nuclei are hit by pulsing radio waves• Once the pulses stop the nuclei go back to

their state induced by the magnet• The energy now released by the nuclei giving

out a signal• These radio waves are picked up by a computer

where they are translated into an image.

The Uses of the MRI• Diagnosing: strokes; masses in soft tissue,

infections of the brain/spine/CNS;• Useful in the investigation of posterior fossa

disease, also visualizes temporal lobes in investigating epilepsy.

• It effective in picking up inflammatory conditions such as multiple sclerosis.

• MRI can also be applied to delineate arterial (MRA for aneurysms) or venous anatomy (MRV for CVT).

Types of MRI imagings

• T1WI (good for anatomical details) • T2WI (for highlighting pathology) • Post-Gd images• FLAIR T2W images (edema) • STIR• DWI• ADC• GRE (blood) • MRA, MRV

Advantages -No ionising radiation -Non-invasive - High-quality soft tissue images - No bone artifact

Disadvantages -Expensive -Less widely available -Movement artifacts -Severe claustrophobia (5%)

Contraindications •Implanted cardiac pacemakers •Ferromagnetic aneurysm clips, •Metallic implants •Relatively contraindicated during the first trimester of pregnancy leading to miscarriage.

Motion artifacts( ghost)

MRI:

Transverse (“Axial”)

Coronal Sagittal

Purposes

Pathologic evaluation T2W images are more sensitive than T1W images to edema, demyelination, infarction Recognition CSF / sulci - bright Cranium - bright Eyes - bright Brain tissue – neutral gray Abnormal tissue - bright

4-Ultrasound ( Doppler, Duplex scans) as screening tool to assess need for carotid endarterectomy.

5- MYELOGRAPHY5- MYELOGRAPHY • CT myelography used for localization of spinal dural

arteriovenous fistulas.

6- ANGIOGRAPHY• Catheter angiography Vasculitis , Vascular malformations (aneurysms),• The most feared complication of cerebral angiography

is stroke

7- Radio-isotope SPECT:movement disorders, epilepsy, dementias

, PET

INTERVENTIONAL NEURORADIOLOGY

• Detachable coil therapy for aneurysms• Liquid adhesive embolization of

arteriovenous malformations• Balloon angioplasty and stenting of

arterial stenosis or vasospasm• Preoperative embolization of tumors• Thrombolysis of acute arterial or venous

thrombosis.

1-Electroencephalogram (EEG)2-ElectroneuromyographY (ENMG)3-Evoked potential studies VEP, BSAEP & SSEP

B.Neurophysiological testing

• EEG is used to detect electrical activity arising in the cerebral cortex.

• The EEG involves placing electrodes on the scalp to record the amplitude and frequency of the resulting waveforms.

• EEG being performed during ictal and interictal phases. It can be recorded with video monitoring.

• Over 50% of patients with proven epilepsy will have a normal ‘routine’ EEG

• Up to 5% of some normal populations may demonstrate epileptiform discharges on EEG

1- Electroencephalogram (EEG)

Basic EEG frequencies

The EEG in used in

• Epilepsy classification and prognosis• Localise the seat of epileptiform

discharges when surgery is being considered.

• Encephalopathy/encephalitis• Sleep disorders • Confirming brain death (not essential).

2-Electroneuromyographic (ENMG) Examination

• Nerve conduction studies (NCS), that are sensory, motor, or mixed, and the needle EMG. RNS, SFEMG

• NCS is the recording and measurement of the compound nerve and muscle action potentials elicited in response to an electrical stimulus.

• NCS can test only medium- to large-diameter myelinated fibers.

NCS is helpful in • Existence of a neuropathy, its severity

• Distribution (i.e., whether it is distal, proximal, or diffuse)

• Modality involved (i.e., motor versus sensory)

• Whether the lesion is axonal or demyelinating.

Electromyography (EMG) • The electrical activity of muscles is

recorded by inserting a small needle electrode into the muscle.

• Amplified recording from muscle is viewed on an oscilloscope and heard through a speaker.

• Documenting myopathic, myotonic, myasthenic changes.

3-Evoked potential studies• Assess the sensory pathways from the

sensory organ to the cerebral cortex, visual (VEP), brain stem auditory (BSAEP) and somatosensory (SSEP) evoked potentials.

• A delay in the potential implies demyelination while a reduction in amplitude suggests axonal degeneration.

C. Lumbar puncture (LP)• LP is the technique used to obtain a CSF

sample and provides an indirect measure of intracranial pressure.

• It is usually a safe procedure.• Analysis CSF will involve: Cell count with

diff., Protein , Glucose ,Culture ,Smears.• More sophisticated analysis : PCR for

herpes simplex or tuberculosis), Oligoclonal bands & Cytology.

Lumbar PunctureLumbar Puncture

LP for DxLP for Dx

High ICP, e.g.,IIH.High ICP, e.g.,IIH. Infections, e.g. Infections, e.g.

meningitis.meningitis. Demyelinating Demyelinating

diseases, e.g., M.S.diseases, e.g., M.S. Bleeding, e.g., SAH.Bleeding, e.g., SAH. Introducing contrast Introducing contrast

agent for Dx, e.g., DH,agent for Dx, e.g., DH,….….

LP for RXLP for RX

High ICP, e.g.,IIH.High ICP, e.g.,IIH. Malignancies, e.g., Malignancies, e.g.,

leukemia.leukemia. Anesthesia.Anesthesia.

Pressure : 50–250 mm of water . Colour : Clear. Cells : CSF is normally nearly acellularo Red cell count 0–4 (× 106/L)o White cellcount 0–4 (× 106/L) Glucose : > 50–60% of blood level. Protein : < 0.45 g/L. Microbiology : Sterile Oligoclonal bands : Negative

Composition of normal CSF

Contraindications for Lp• A cranial SOL causing raised ICP,

“Coning”.• Consequently, LP is C/I if there is any

clinical suggestion of raisedICP (papilloedema), depressed LOC, new-onset seizure, or focal neurological signs suggesting a cerebral lesion, until imaging (by CT or MRI) has excluded a SOL or hydrocephalus.

• TCP, DIC or anticoagulant• Infected skin

Complications of Lp

1-About 30% of LPs are followed by a postural headache,due to reduced CSF pressure. 2-transient radicular pain.3-Aseptic technique renders secondary infections such as meningitis extremely rare.

OTHERS• Full blood count, ESR,C-reactive protein,

biochemical,Drug/toxin screen, Immunological tests, Acetylcholine receptor, VDRL, HIV ….etc

• Genetic testing by DNA analysis as in Huntington’s disease

• Biopsies of nervous tissue Nerve biopsy (e.g leprosy ,vasculitis). Muscle biopsy (myositis/myopathies). Artery biopsy : GCA Brain biopsy: primary and metastatic

brain tumors , CJD