Ring-Enhancing Lesions in the Brain

Question 1. Write a short note on neurological indications for MRI.
Answer:

Advantages and disadvantages of MRI

The advantages and disadvantages of MRI.

Contrast MRI

Gadolinium is used as intravenous contrast to assess the vascularity in tumors and inflammatory lesions.

Side effects: Headache, nausea, pain and sensation of cold at the injection site, dizziness, and rarely nephrogenic systemic fibrosis (fibrosis of dermis, joints, and internal organs including lungs and heart).

Contrast (gadolinium) imaging can worsen renal failure, so its best avoided in Acute kidney injury (AKI)/chronic kidney disease (CKD).

Read And Learn More: General Medicine Question And Answers

Neurological indications for MRI.

MRI is the investigation of choice for the evaluation of all neurological disorders:

Structural imaging: Produces high-quality soft tissue images.

• Useful in the investigation of diseases of the posterior fossa and temporal lobes, inflammatory conditions (e.g., multiple sclerosis), and in investigating epilepsy.
• Magnetic resonance angiography (MRA) to study blood vessels in the neck or brain

Functional MRI: Mainly research tools

MR spectroscopy: Mainly research tools

Special forms of MRI

Diffusion MRI:

• To measure the movement or diffusion of extracellular water molecules.
• MR angiography helps us to evaluate intracranial vessels noninvasively to find aneurysms, stenosis, or malformations.
• Magnetic resonance spectroscopy (MRS)
• Functional MRI to assess blood flow during specific tasks (e.g., speaking, remembering, and calculation).

MRI Complications

MRI is a safe procedure. However, if a metal is present nearby serious injuries may develop when metal gets attracted to strong magnets of MRI and may act like a missile.

X-ray/CT Plain X-rays, CT, CTA

MRI Applications: Radiculography, myelography, intraarterial angiography

X-rays: For fractures or foreign bodies

CT: First line for stroke

Intra-arterial angiography: Gold standard for vascular lesions

MRI Advantages:

• Easily available, relatively economical, and relatively quick.
• Ultrasound-Doppler Studies
• Cheap, quick, and noninvasive.
• B-mode and color ultrasound are useful in identifying carotid stenosis.

Radioisotope

For establishing the diagnosis, we need to do a radioisotope scan, SPECT, and PET.

Question 2. Discuss the differential diagnosis for “ring-enhancing lesions”.
Answer:

It is abnormal radiological findings observed in MRI or CT scans obtained using radiocontrast.

In the image, it appears as an area of decreased density surrounded by a bright rim from the concentration of the enhancing contrast dye

Causes for Ring-enhancing Lesions in the Brain

Infections: Early brain abscess, tuberculoma, CNS toxoplasmosis, cysticercosis, fungal infections (nocardiosis, cryptococcosis), neurosyphilis.

Inflammatory: Demyelinating disorders (MS, ADEM), sarcoidosis, Behçet’s disease, Whipple’s disease.

Vascular: Cerebral venous thrombosis and several other vasculitic disorders.

Neoplastic: Primary (For Example., glioblastoma, low-grade gliomas, CNS lymphoma) and metastasis.

Magnetic Resonance Spectroscopy

Magnetic resonance spectroscopy is a means of noninvasive physiologic imaging of the brain that measures relative levels of various tissue metabolites.

Magnetic resonance spectroscopy patterns in diseases

Time of Echo (TE) that conditions the number of metabolites

• Lactate: Resonates at 1.33 ppm
• Lipids: Resonates at 1.3 ppm
• Alanine: Resonates at 1.48 ppm
• N-acetyl aspartate (NAA): Resonates at 2.0 ppm
• Glutamine/Glutamate: Resonates at 2.2–2.4 ppm
• GABA: Resonates at 2.2–2.4 ppm
• 2-Hydroxyglutarate: Resonates at 2.25 ppm
• Citrate: Resonates 2.6 ppm
• Creatine: Resonates at 3.0 ppm
• Choline: Resonates at 3.2 ppm
• Myo-inositol: Resonates at 3.5 ppm
• Glucose: Resonates at 3.43 ppm and 3.8 ppm
• Mannitol: Resonates at 3.78 ppm
• Water: Resonates at 4.7 ppm
• Diseases MRS patterns
• Glioma NAA and creatine decrease and choline, lipids, and lactate increase.
• Radiation effects NAA, choline, and creatine will all be low
• Ischemia and infarction Lactate will increase, later lipid peak appears
• Infection NAA is absent, and lactate, alanine, cytosolic acid, and acetate are elevated.

Note: Choline is low or absent in toxoplasmosis, whereas it is elevated in lymphoma, helping to distinguish the two Progressive multifocal leukoencephalopathy (PML) Elevated Myo-inositol Canavan disease Elevated NAA Hepatic encephalopathy Markedly reduced Myo-inositol and choline.
Glutamine increased Leigh’s syndrome Elevated choline, reduced NAA
Neurophysiological Testing

Question 3. Write a short note on electroencephalography.
Answer:

Electroencephalography

The electroencephalogram was recorded from the scalp by placing electrodes on the scalp.

It is used to detect electrical activity arising in the cerebral cortex. Rhythmic activity is recorded as waves (alpha, beta, gamma, theta, mu, and delta).

Usefulness:

In progressive and continuous disorders such as reduced consciousness, classification and prognosis in epilepsy and diffuse brain diseases [encephalitis, prion (Creutzfeldt–Jakob) diseases and metabolic states (e.g., hypoglycemia, hepatic coma)].

• Diagnosis of paroxysmal neurological attacks
• Differentiation between nocturnal epilepsy and parasomnias
• Diagnosis of psychogenic nonepileptic seizures
• Characterization of seizure type
• Quantification of interictal epileptiform discharge (IED) or seizure frequency
• Evaluation of candidates for epilepsy surgery.
• Video EEG: Useful in the definitive diagnosis of epilepsy.
• Ambulatory EEG is analog to the Holter monitor for cardiac arrhythmias.

Lathyrism

Question 4. Write a short note on lathyrism.
Answer:

Lathyrism is a paralyzing disease caused by eating seeds of Lathyrus sativus (khesari dal).

Epidemiology

It is prevalent mostly in people in India (e.g., Madhya Pradesh, Uttar Pradesh, Bihar, and Odisha), Bangladesh, Pakistan, Nepal, and Algeria.

Etiology

• L. sativus (khesari dal) is a good source of protein. It is a relatively cheap pulse and is consumed mostly by the poor agricultural laborer. But it contains L-ODAP (β-N-oxalyl-l-α,β-diaminopropionic acid) also called β-N-oxalylamino-L-alanine, or BOAA, which is an excitatory neurotoxin and glutamate agonist.
• If diets containing > 30% of this dal are consumed over a period of 2–6 months will produce lathyrism.

Clinical Features

It affects mainly young males between 15 and 45 years of age. In humans, it mainly affects the nervous system and is called neurolathyrism which produces pure motor spastic paraplegia.

Sensations and sphincters are preserved.

Stages

Latent stage: Patient appears healthy but when subjected to physical stress exhibits ungainly gait.

If the disease is recognized at this stage, age, and withdrawal of pulse from the diet will result in complete remission of the disease.

No-stick stage: During this stage, the patient walks with difficulty having short jerky steps but does not need the aid of a stick.

One-stick stage: The patient walks with a crossed gait, has a tendency to walk on her toes, and develops musculoskeletal stiffness.

The use of a stick is necessary to maintain balance.

Two-stick stage: Symptoms are more severe at this stage. Due to excessive bending of the knees and crossed legs, the patient requires support by two crutches for support.

The gait is slow and clumsy and he complains of easy tiredness after
walking a short distance.

Crawler stage: Finally spastic paralysis develops which becomes irreversible.

It becomes impossible to maintain an erect posture as the knee joints cannot support the weight of the body.

The thigh and leg muscles become atrophied and the patient crawls by throwing his weight on his hands.

Prevention

• Vitamin C prophylaxis: 500–1,000 mg for a week.
• Banning the crop if possible.
• Removal of toxin:

Steeping method: Soak the pulse in hot water for 2 hours and the soaked water is drained off completely.

• The pulse is washed again with clean water and then drained off and dried in the sun.
• There will be a loss of vitamins and minerals by this method.

Parboiling: Suitable for large-scale operation and is similar to parboiled rice. It destroys trypsin inhibitors.