Diagnostic Evaluation and Treatment modalities of the Nervous System

Magnetic Resonance Imaging (MRI)

Uses a strong magnetic field and radio waves to create images. Hydrogen atoms in the body produce signals that form images. Can be done with or without contrast. Provides clearer and earlier detection of abnormalities than CT. Shows cellular and chemical changes. No ionizing radiation

DWI (Diffusion-weighted imaging) → detects early stroke

PWI (Perfusion-weighted imaging) → shows blood flow

MRS (Magnetic resonance spectroscopy) → shows chemical changes

FLAIR → highlights brain lesions

MRA (Magnetic resonance angiography) → shows blood vessels without arterial contrast

Special MRI Techniques

Positron Emission Tomography (PET)

a method of brain imaging that assesses metabolic activity by using a radioactive substance injected into the bloodstream. Measures Blood flow, Glucose (energy) use Oxygen metabolism

Single-Photon Emission Computed Tomography (SPECT)

radiological technique that integrates computed tomography (CT) and a radioactive material (tracer) injected into the bloodstream to visualize blood flow to tissues and organs at a specific moment. Detects stroke early (before CT changes appear)

Cerebral Angiography

An x-ray study of brain blood vessels using a contrast agent. Used to evaluate cerebral circulation. Detects aneurysms, arteriovenous malformations (AVMs), or vascular abnormalities. A catheter is inserted into the femoral artery (groin) or radial artery (wrist). Patient may feel warmth in face or jaw, and a metallic taste

Myelography

An x-ray of the spinal cord and subarachnoid space. Contrast is injected into the CSF via lumbar puncture. Elevate head 30-45° afterwards

Noninvasive Carotid Flow Studies

Use ultrasound and Doppler to assess blood flow. Evaluates carotid arteries and orbital circulation. Detects stenosis (narrowing), occlusion (blockage), or plaques

Transcranial Doppler

A noninvasive Doppler test for brain blood flow. Measures flow in intracranial vessels. Probe placed on skull (temporal/occipital areas). Sound waves reflect off moving blood cells

Electroencephalography (EEG)

test that records the electrical activity of the brain. Electrodes are placed on the scalp (or sometimes inside the brain). Used to diagnose and evaluate seizure disorders (epilepsy), coma, brain disorders (tumors, infection, clots), and to help determine brain death

Electromyography (EMG)

A test that measures electrical activity of muscles. Uses needle electrodes inserted into muscles. Diagnoses neuromuscular disorders, muscle diseases (myopathies). Helps distinguish nerve problems (neuropathy) from muscle-related weakness. Needle insertion feels like intramuscular injection. Mild soreness may be felt after.

Nerve Conduction Studies (NCS)

A test that measures how fast and well nerves transmit signals. Nerves are stimulated at different points. Responses are recorded from muscles or sensory nerves. Surface or needle electrodes are placed on the skin. Electrical stimulation is applied. The resulting nerve or muscle response is recorded. Evaluates peripheral nerve function

Evoked Potential Studies

Measures the brain's electrical response to sensory stimuli. Evaluates nerve conduction pathways

Visual Evoked Potentials (VEP), Brainstem Auditory Evoked Responses (BAER), Somatosensory Evoked Responses (SER)

Types of Evoked Potentials

Visual Evoked Potentials (VEP)

Stimulus: flashing lights or patterns

Measures signal from eye to occipital lobe

Detect visual pathway problems

Brainstem Auditory Evoked Responses (BAER)

Stimulus: clicking sounds

Measures signal through auditory pathway and brainstem

Detect brainstem lesions

Help determine brain death

Somatosensory Evoked Responses (SER)

Stimulus: electrical stimulation of peripheral nerves

Measures signal from nerves → spinal cord → brain

Detects spinal cord disorders, peripheral nerve problems, or demyelinating diseases (e.g., multiple sclerosis)

Also used during surgery to monitor spinal cord functionq

Caloric Testing

Evaluates vestibular (CN VIII) function and brainstem integrity. Used in coma assessment or suspected vestibular disorders. Patient lies supine with head elevated ~30°

Warm or cold water is irrigated into the ear canal

Observe eye movement (nystagmus)

Cold water → eyes drift toward irrigated ear, then rapid movement away

Warm water → opposite response

Normal Responses in Caloric Testing

Cerebrospinal Fluid (CSF) Analysis

is a set of laboratory tests that examine the clear fluid surrounding the brain and spinal cord, typically collected via lumbar puncture (spinal tap). It is crucial for diagnosing central nervous system infections (meningitis, encephalitis), autoimmune disorders (multiple sclerosis), hemorrhages, and tumors

Lumbar Puncture (LP)

diagnostic procedure performed by insertion of a needle into the subarachnoid space usually between L3-L4 or L4-L5; performed for many reasons, including the removal of cerebrospinal fluid (also called spinal tap) and measuring of intracranial pressure. Flat bed rest (4-12 hours) and encourage hydration afterwards

Intracarotid Amobarbital Procedure (Wada Test)

a presurgical diagnostic test used primarily in patients with refractory epilepsy to determine which hemisphere controls language and to evaluate memory function. It involves injecting a sedative (sodium amobarbital) into one carotid artery to temporarily put half the brain to sleep, allowing for independent testing of the other side's abilities. Determines dominant brain hemisphere (speech, memory)

Tensilon Test

a diagnostic procedure for myasthenia gravis (MG) that involves injecting edrophonium chloride, a rapid-acting medication, to see if it temporarily improves muscle strength. It acts by blocking the breakdown of acetylcholine, allowing better nerve-muscle communication. A positive result is shown by a brief improvement in muscle strength, particularly reversing ptosis (droopy eyelids). Have atropine ready (for bradycardia)

Polysomnography (Sleep Study)

measures physiological activity during sleep and is often performed to detect nocturnal defects in breathing associated with sleep apnea

Neuropsychological Testing

assessment of brain and nervous system functioning by testing an individual's performance on behavioral tasks

Craniotomy

a neurosurgical procedure where a portion of the skull (bone flap) is temporarily removed to access the brain for treating conditions like tumors, aneurysms, or blood clots. The bone flap is secured back in place after the procedure.

Craniectomy

a major neurosurgical procedure where a portion of the skull is removed to relieve dangerous pressure on the brain caused by swelling, bleeding, or trauma. Unlike a craniotomy, the bone flap is not immediately replaced. A subsequent procedure, cranioplasty, is required later to replace the skull piece

Clipping / Ligating Aneurysm

Prevent rupture or rebleeding of cerebral aneurysm. metal clip placed on aneurysm neck (open surgery)

Endovascular embolization

The repair of a brain aneurysm by the insertion of soft metal coils into the aneurysm to block it off and stop bleeding.

Cranioplasty

repair of cranial defect using a plastic or metal plate

Transsphenoidal Surgery

Surgery on pituitary gland; incision made through base of sphenoid sinus. Monitor for CSF leak (clear nasal drainage)

Do NOT allow coughing, sneezing, and of blowing nose

Monitor for diabetes insipidus and hormonal imbalance. Elevate head of bed

Tarsorrhaphy

a surgical procedure that partially or fully joins the upper and lower eyelids to protect the cornea from damage caused by severe dry eye, nerve damage, or persistent corneal ulcers. Usually performed on one eye, this "eye cast" can be temporary (sutures, tape, or glue) or permanent to promote healing

Rhizotomy

a minimally invasive procedure that destroys specific nerve fibers responsible for chronic pain or spasticity, typically providing relief for several months to years. Using radiofrequency, chemicals, or surgical cutting, it interrupts pain signals between the spinal cord and brain, often used for back pain, neck pain, or muscle spasms

Carotid Endarterectomy

the surgical removal of the lining of a portion of a clogged carotid artery leading to the brain

Extra/Intracranial Anastomosis (Bypass Surgery)

a specialized microsurgical procedure that restores blood flow to the brain by connecting an extracranial artery (usually the superficial temporal artery) to an intracranial artery, bypassing blockages. Primarily used for stroke prevention, complex aneurysms, and Moya-moya disease, it treats ischemic conditions

Intracranial Pressure (ICP) Monitoring

a neurosurgical procedure that involves placing a sensor into the skull to continuously measure pressure surrounding the brain. Measures pressure inside the skull. Normal is 5 - 10 mmHg. recommend initiating treatment if >20 mmHg. Types: ventricular catheter (most accurate), subarachnoid bolt, or epidural sensor

Pallidotomy

Surgical destruction of the globus pallidus of the brain done to treat involuntary movements or muscular rigidity in Parkinson's disease