Neurology

Davidson 23rd; P-1082

CSF is obtained from lumber puncture.

Encephalitis is the inflammation of brain parenchyma.

Reference: Davidson 23rd; P- 1150 (Box-26.1)

Generalised cortical atrophy, particularly in the hippocampus and temporal lobes, is the hallmark imaging finding in Alzheimer’s disease. Davidson explains that atrophy reflects the loss of neurons and synapses in affected brain regions. Harrison adds that MRI or CT imaging can help support the clinical diagnosis, but definitive diagnosis still relies on clinical features and histopathology, if available.

Myasthenia gravis is an autoimmune disease, most commonly (80% of cases) caused by antibodies to acetylcholine receptors in the post-junctional membrane of the neuromuscular junction. The resultant blockage of neuromuscular transmission and complement-mediated inflammatory response reduces the number of acetylcholine receptors and damages the end plate (Fig. 28.50). Other antibodies can produce a similar clinical picture, most notably autoantibodies to muscle-specific kinase (MuSK), which is involved in the regulation and maintenance of acetylcholine receptors.

Reference: Davidson 23rd; P-133

This is a sign of meningitis.

Explanation: Infarct (85%), Haemorrhage (15%), venous (1%)

Reference: Davidson 23rd, Page: 1066 , Box : 25.2

Reference: Davidson 23rd; P-758

Reference: Davidson 23rd; P-1088(Fig-25.19)

Explanation: Campylobacter species have been linked to GBS & post infectious reactive arthritis.

Hyperreflexia is not a feature of myasthenia gravis. Davidson describes myasthenia gravis as an autoimmune disorder that causes muscle weakness and fatigue, particularly affecting the ocular, facial, and limb muscles. Diplopia (double vision) and ptosis (drooping eyelids) are common presenting symptoms. Harrison explains that reflexes are usually normal, and fatigue increases with activity, improving with rest.

Reference: Davidson 23rd; P- 1115

The 5 classic lacunar syndromes, established by Fisher in the 1960s and 1970s, are pure motor hemiparesis, pure sensory stroke, sensorimotor stroke, ataxic hemiparesis, and clumsy-hand dysarthria.

Explanation: Chloroquine- Antimalarial drug, Isoniazid is anti-TB drug

Explanation: Lumbar puncture is mandatory unless there are contraindications in a patient of meningitis

Reference: Davidson 23rd; P-145
সলভ ক্লাসের জন্য আলোচনা পোস্ট দেখুন - [আলোচনা পোস্টের লিঙ্ক]

Viruses are the most common cause of meningitis, usually resulting in a benign and self-limiting illness requiring no specific therapy. It is much less serious than bacterial meningitis unless there is associated encephalitis. A number of viruses can cause meningitis (see Box 28.59), the most common being enteroviruses. Where specific immunisation is not employed, the mumps virus is a common cause.

An ataxic gait can result from lesions in the cerebellum, vestibular apparatus or peripheral nerves

Extension of pituitary tumor into avernous sinus with subsequent compression of the 3rd, 4th or 6th  cranial nerve may cause diplopia and strabismus, but in anterior pituitary  tumours this is an unusual presentation.

Davidson 24th-695

Astrocytes form the structural framework for neurons and control their biochemical environment, their foot processes adjoining small blood vessels and forming the blood–brain barrier (Fig.28.1).

Oligodendrocytes are responsible for the formation and maintenance of the myelin sheath, which surrounds axons and is essential for maintaining the speed and consistency of action potential propagation along axons. Peripheral nerves have axons invested in myelin made by oligodendrocytes (Schwann cells).

Microglial cells derive from monocytes/macrophages and play a role in fighting infection and removing damaged cells.

Ependymal cells line the cerebral ventricles.

Reference: Davidson 23rd, Box-25.87

Reference: Davidson 23rd; P- 1112 (Box-25.55)

Stem Breakdown:

Sudden-onset severe headache ("thunderclap" headache), nausea, and vomiting: These are classic symptoms of a subarachnoid hemorrhage (SAH), a life-threatening condition often described as the "worst headache of my life."
Neck stiffness and photophobia: These symptoms suggest meningeal irritation, which occurs when blood irritates the meninges in SAH.
Blood in the subarachnoid space on CT: This confirms the diagnosis of SAH.
Option Analysis:

A) Subarachnoid hemorrhage: This is the correct diagnosis. Davidson and Harrison explain that subarachnoid hemorrhage (SAH) is most commonly caused by the rupture of a cerebral aneurysm, leading to bleeding into the subarachnoid space. The sudden onset of a severe headache, often described as "thunderclap," and the presence of blood on CT are diagnostic of SAH.
B) Migraine headache: Migraine can cause severe headache with nausea and photophobia, but it typically has a gradual onset and is often preceded by an aura. It is not associated with neck stiffness or blood in the subarachnoid space.
C) Meningitis: Meningitis can cause headache, neck stiffness, and photophobia, but it would not cause blood in the subarachnoid space on CT. Lumbar puncture would show infection (e.g., elevated white blood cells in the cerebrospinal fluid).
D) Tension headache: Tension headaches are usually mild to moderate, with a band-like distribution of pain around the head. They are not associated with sudden onset, nausea, vomiting, or blood in the subarachnoid space.

Davidson 23rd; P-1118

A) Retinal artery occlusion: This is the correct diagnosis. Davidson and Harrison explain that central retinal artery occlusion is caused by an embolus or thrombus blocking blood flow to the retina, leading to sudden, painless vision loss. The pale retina and "cherry red spot" are classic fundoscopic findings.
B) Retinal vein occlusion: Retinal vein occlusion causes painless vision loss, but the fundoscopy would show "blood and thunder" appearance with dilated veins, hemorrhages, and cotton-wool spots, not a pale retina with a cherry red spot.
C) Diabetic retinopathy: Diabetic retinopathy causes vision loss over time due to microvascular damage from diabetes. Fundoscopy reveals microaneurysms, hemorrhages, and neovascularization, not the findings described here.
D) Acute glaucoma: Acute glaucoma causes sudden, painful vision loss due to increased intraocular pressure. It is associated with a red, painful eye and a hazy cornea, not the fundoscopic findings described.

Explanation: Viruses are the most common cause of meningitis, usually resulting in a benign and self-limiting illness requiring no specific therapy. It is much less serious than bacterial meningitis unless there is associated encephalitis. A number of viruses can cause meningitis, the most common being enteroviruses

Explanation: CT is is the first line investigation of stroke

Stem Breakdown:

Episodic dizziness, tinnitus, and hearing loss: This triad of symptoms is classic for Meniere’s disease, a disorder of the inner ear.
Left ear involvement: Meniere’s disease often affects one ear initially.
Option Analysis:

A) Benign paroxysmal positional vertigo (BPPV): BPPV causes brief episodes of vertigo triggered by head movements, but it is not associated with hearing loss or tinnitus.
B) Meniere’s disease: This is the correct diagnosis. Davidson and Harrison explain that Meniere’s disease is caused by abnormal fluid accumulation in the inner ear, leading to episodes of vertigo, tinnitus, and fluctuating hearing loss. It is typically unilateral, affecting one ear initially.
C) Vestibular neuritis: Vestibular neuritis causes acute vertigo due to inflammation of the vestibular nerve, but it does not cause hearing loss or tinnitus.
D) Acoustic neuroma: Acoustic neuroma (vestibular schwannoma) can cause unilateral hearing loss and tinnitus, but it typically presents with gradual onset rather than episodic symptoms. Vertigo is less common.

Davidson 23rd; P-1102

Explanation: The temporal lobes contain the primary auditory cortex and primary vestibular cortex

Vomiting without nausea–raised intracranial pressure (ICP)
Projectile vomiting–gastric outlet obstruction
Pain abdomen relieved by vomiting–gastric ulcer
Vomiting with absolute constipation–intestinal obstruction

Explanation:
Stem Breakdown:

Sudden-onset weakness and difficulty speaking: These are classic signs of a stroke.
CT showing ischaemia in the left middle cerebral artery (MCA): This confirms that the stroke is ischaemic in nature.
Option Analysis:

A) Transient ischaemic attack (TIA): A TIA involves brief episodes of neurological dysfunction caused by temporary ischaemia without infarction. In this case, the CT scan shows ischaemia, indicating tissue damage, which rules out TIA.
B) Ischaemic stroke: This is the correct diagnosis. Davidson and Harrison explain that ischaemic strokes are caused by obstruction of a cerebral artery, leading to tissue infarction. Sudden-onset weakness (hemiparesis) and difficulty speaking (aphasia) are typical of a left MCA stroke.
C) Hemorrhagic stroke: Hemorrhagic stroke involves bleeding into the brain tissue, often presenting with a more severe clinical picture, including altered consciousness, headache, and vomiting. In this case, the CT shows ischaemia rather than haemorrhage.
D) Subdural haematoma: Subdural haematoma results from venous bleeding, typically following head trauma, and presents with a gradual onset of symptoms like confusion and headache. It does not present with acute ischaemic findings on CT.

A ruptured aneurysm is the most common cause of non-traumatic subarachnoid hemorrhage. Davidson explains that aneurysms, particularly berry aneurysms in the circle of Willis, are prone to rupture, causing bleeding into the subarachnoid space. Harrison highlights that patients typically present with a sudden, severe "thunderclap" headache, and diagnosis is confirmed with CT or lumbar puncture showing blood in the cerebrospinal fluid.

X-rays: used for fractures or foreign bodie
CT: Firrst line for stroke