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Table of Contents
- Head trauma; Head injuries: Extradural hematoma, Subdural hematoma, SAH, Intracerebral hematoma, Intraventricular hemorrhage, Pathophysiology of head injuries (Cushing’s reflex), Management
- Stroke and Localizing the lesion
- Spinal cord - Injuries: Anterior cord syndrome; Posterior cord syndrome; Cauda Equina syndrome; Brown-Sequard syndrome; Central cord syndrome
- Neurological eye conditions; Visual field defects; Ocular movement disorders
- Genetic conditions: VHL
High-yield / Revision Questions
Given the following optic defects, name their respective locations: 🌟
Monocular vision loss → lesion?
- Optic nerve lesion
Bitemporal hemianopia → lesion?
- Optic chiasm lesion
Homonymous hemianopia → lesion?
- Optic tract lesion
Homonymous upper quadrantanopia → lesion?
- Temporal lobe lesion
- Since superior = temporal 🌟 “PITS” mnemonic
- Note that contralateral lesion produces contralateral visual defect
Homonymous lower quadrantanopia → lesion?
- Parietal lobe lesion
- “PITS” mnemonic
- Note that contralateral lesion produces contralateral visual defect
Q: What type of visual field defect is most likely to be noted in a patient with a craniopharyngioma? 🌟
- Lower bitemporal quadrantanopia or hemianopia
- Lesions at the optic chiasm classically results in a bitemporal hemianopia. However, lesions that compresses anteriorly to the chiasm will affect fibers that are worse in the upper fields. If the lesion is located posteriorly to the chiasm, such as craniopharyngiomas, which compress fibers corresponding to inferior temporal quadrants, the visual defect will be worse in lower quadrants.
Management Q’s: 🌟
Q: A motorcyclist was hit by a van. Unfortunately, he was not wearing a helmet. He p/w GCS 3/15 and was intubated. CT reveals cerebral contusion w/o any localizing clinical signs. What is the most appropriate course of action? - Burr hole decompression; Decompressive craniotomy; Insertion of ICP monitoring device; Administration of iv mannitol; Parietotemporal craniotomy
- Ans: Insertion of ICP monitoring device
- This pt may develop raised ICP over the next couple of days; hence, ICP monitoring will help w/ managing their condition.
Q: A pt develops subarachnoid hemorrhage and collapses. At present, she has no evidence of raised ICP. What drug should be given to mx her condition? - None; Atenolol; Labetalol; Nimodipine; Mannitol
- Ans: Nimodipine
- Nimodipine is a type of CCB (calcium channel blocker) - it reduces cerebral vasospasm and is known to improve pt outcomes. Thus, it is administered in most cases of SAH.
[more high-yield Q’s and tips in our notes]
Head Trauma
What is the initial investigation of choice? 🌟
- Head CT
Summary - Depressed skull fracture:
- Depressed skull fx - aka. Signature fractures - occur due to the focal impact of a moving object on the cranium, which disrupts bone structures and drives fracture fragments into the brain.
- Surgery is opted for open fractures or intracranial hematomas.
- Conservative tx is for uncomplicated fractures w/o significant cosmetic deformities.
- Imaging of choice is CT scan.
What are the indications for a CT head? 🌠
Within 1hr (5)
- GCS <13 on initial assessment OR GCS<15 after 2hrs
- Open / depressed skull fractures, basal skull fractures
- Focal neurological deficit
- Post-traumatic seizure
- Vomiting more than once
Within 8hrs (5)
- Any loss of consciousness or amnesia, AND one of the following:
- 65yo or older
- Coagulopathy
- High impact injury
- Retrograde amnesia >30mins (retrograde = loss of past memories; vs anterograde = unable to form new memories)
Toggle flowchart from NICE guidelines:
[more high-yield details in our notes]
Head injuries
For the following clinical presentations, what are their respective brain bleeds? (5)🌟
CT head shows biconvex lesion + lucid interval + trauma to side of skull (pterion and middle meningeal artery affected)
- Extradural hemorrhage
Spontaneous brain bleed in a healthy athletic marathon runner
- Subarachnoid hemorrhage
More frequent in premature neonates + occurs spontaneously 🌟
Intraventricular hemorrhage - Q: A known complication is ~? 🌟
- Hydrocephalus (since CSF flow is blocked)
Which hematoma is more lethal - extradural or subdural? 🌟
- Subdural hematoma
Summary of key words and their respective brain bleeds: 🌠
Extradural hemorrhage ⇒ Biconvex hyperdense lesion on head CT 🍋, lucid interval, trauma to side of the skull, pterion, middle meningeal artery injury
- Note that Lucid interval = A period btwn regaining consciousness after a short period of unconsciousness resulting from head injury and deteriorating after the onset of symptoms.
- Subdural hemorrhage ⇒ Old age, alcoholic, crescent-like hyperdense lesion on head CT (banana shaped) 🍌
- Subarachnoid hemorrhage ⇒ Spontaneous bleed, may have accompanying neck stiffness + photophobia, healthy and athletic person (e.g., marathon runner)
- Intraventricular hemorrhage ⇒ Premature neonates
Image of brain bleeds:
Pathophysiology of head injuries:
Triad of Cushing reflex 🌟(3) Increased ICP results in ~:
Memory aid: two Rates down; two Pressures raised!
- Increased BP (hypertension)
- Decreased HR (bradycardia)
- Decreased RR (bradypnea)
Summary of Cushing reflex: 🌠
It is a triad, which results in: Hypertension, Bradycardia & Bradypnea
- Memory aid: 2 pressures increased (ICP and BP) and 2 rates decreased (HR and RR)
- This is a result of increased ICP greater than MAP (mean arterial pressure) → compression of cerebral arterioles → cerebral ischemia
- Both sympathetic and parasympathetic systems are activated!
[more high-yield details in our notes]
Extradural / Epidural hematoma
What bones form the pterion? (4) 🌟
- Squamous part of temporal bone
- Greater wing of sphenoid bone
- Parietal bone
- Frontal bone
Summary of Extradural / Epidural hematoma: 🌠
- Bleeding takes place in the space btwn the dura mater and skull.
- Types of injury that may result in this hematoma include: Acceleration-deceleration trauma or a blow to the side of the head (specifically where the pterion is located).
- Majority of EDH occur in the temporal region at the site of the pterion, as a fracture here may rupture the middle meningeal artery.
- Stages of disease progression: Concussion (immediate LOC after trauma) → Lucid interval (sudden improvement from concussion) → Decreased GCS (from increasing ICP)
- CT head reveals biconvex hyperdense lesion - lemon-shaped 🍋
[more high-yield details in our notes]
Stroke
Anterior circulation includes ~aa: (2)
- Anterior cerebral arteries
- Middle cerebral arteries
Posterior circulation includes ~aa: (6)
- Vertebral arteries combine to form:
- Basilar artery divides to form → Posterior cerebral artery (PCA), Superior cerebellar artery (SCA), pontine aa., Anterior inferior cerebellar artery (AICA) & Posterior inferior cerebellar artery (PICA)
Recap Dr. Peter Gates' "rule of four of the brainstem" 🌠
- 4 cranial nerves in each: medulla, pons & above pons (i.e., midbrain and beyond)
- 4 cranial nerves that are factors of 12: III, IV, VI, XII → Motor nuclei are Midline
- 4 cranial nerves that are not factors of 12: V, VII, IX, XI → all are Lateral
Toggle for images to better understand localizing lesions via the brainstem's blood supply and anatomical structures: 🌠
Images: Motor and sensory homunculus blood supply - to localize lesions in the brain: 🌠
Q’s re: Localizing lesions - The following clinical presentations indicate a rupture or infarct in which artery / arterial system? (12) 🌟
Isolated hemiparesis, hemisensory loss or hemiparesis with limb ataxia → ?system
- Lacunar infarction - perforating arteries supplying internal capsule, thalamus and basal ganglia
Features of brainstem damage + Ataxia + gaze and or vision disorder + CN lesions → ?system
- Posterior circulation infarction - involving vertebrobasilar arteries
Contralateral hemiparesis + sensory loss, where lower limb more severe than upper limb + cognitive or personality changes → ?artery🌟
- Anterior cerebral artery
Toggle for motor and sensory homunculus blood supply:
Contralateral hemiparesis + sensory loss, where upper limb more severe than lower limb + contralateral hemianopia + gaze abnormalities + Wernicke's aphasia → ?artery🌟
- Middle cerebral artery
Toggle for motor and sensory homunculus blood supply:
Difficulty paying attention or impulsive behavior + contralateral hemianopia with macular sparing → ?artery🌟
- Posterior cerebral artery - affecting occipital lobe
Q: The macular region of the cortex has double blood supply by~: (2)
- MCA & PCA
Ipsilateral CN palsy (either horizontal gaze palsy or facial drooping) + contralateral hemiparesis ~infarction location? Due to occlusion of ~artery?🌟
- Pons
- Pontine artery
Toggle for explanation on gaze palsy:
- Gaze palsy = cannot look to damaged side (since in this case, damaged CN VI = unable to abduct eyeball to lateral side)
- Clinical features described above fit the Medial pontine syndrome, which is different from: Lateral pontine syndrome (by AICA)
- which involves: Ipsilateral pain or temperature loss of the face + Contralateral pain or temperature loss in body and limbs
Acute syncope + Ipsilateral: loss of pain and temperature over face, cerebellar ataxia, nystagmus, tinnitus, dysphagia, Horner's + Contralateral loss of pain and temperature over body and limbs → ~Infarction location? ~Syndrome? Due to occlusion of ~artery?🌟
Lateral medulla - name of syndrome:
aka. (Lateral medullary syndrome) Wallenberg's syndrome - due to occlusion at ~artery:
- PICA
[more high-yield details in our notes]