CNS Pathology Flashcards
Anencephaly is the absence of skull and brain due to failure of cranial closure of neural tube. This results in a ‘frog-like’ appearance of the fetus as well as maternal _______
Polyhydramnios
_____ ______ is failure of posterior vertebral arch to close, leading to meningocele or meningomyelocele. ______ _____ ______ leads to a dimple or patch of hair overlying the vertebral defect
Spina bifida; spina bifida occulta
Cerebral aqueduct stenosis is congenital stenosis of the channel that drains CSF from the _____________________, leading to accumulation of CSF in the ventricles and presents with enlarging head circumference
3rd and 4th ventricles
Congenital failure of the cerebellar vermis to develop, presenting as a massively dilated 4th ventricle with absent cerebellum; often accompanied by hydrocephalus
Dandy-Walker malformation
Congenital extension of cerebellar tonsils through foramen magnum in which obstruction of CSF flow may result in hydrocephalus; also may occur in association with meningomyelocele and syringomyelia
Arnold-Chiari Malformation
Cystic degeneration of the spinal cord that arises with trauma or in association with Arnold-Chiari malformation
Syringomyelia
Syringomyelia usually occurs at level ________, affecting the ________ ______ ________ of the spinal cord, resulting in sensory loss of _____ and _______.
If the syrinx expands into ________ horns, lower motor neuron signs may arise (muscle atrophy and weakness with decreased tone and impaired reflexes). If the _______ horns are affected, patient may present with Horner’s syndrome (ptosis, miosis, anhydrosis).
C8-T1; anterior white commissure; pain; temperature
Anterior; lateral
[Note that fine touch and position sense, which are located in dorsal commissure, are spared in the UE with syringomyelia!]
Poliomyelitis results in damage to _____________ of the spinal cord due to poliovirus infection. These patients present with ___________ signs
Anterior motor horn; lower motor neuron
Autosomal recessive inherited degeneration of anterior motor horn (presents similarly to poliomyelitis), presenting as “floppy baby”; death occurs within a few years after birth
Werdnig-Hoffmann Disease
_______ _______ ______ is a degenerative disorder of upper and lower motor neurons (_______ tract). Anterior motor horn involvement leads to LMN signs, while _______ ______ _____ involvement leads to UMN signs.
Amyotrophic Lateral Sclerosis; Corticospinal; Lateral corticospinal tract
Atrophy and weakness of hands is an early sign of ALS. How is ALS distinguished from syringomyelia?
Lack of sensory impairment distinguishes ALS from syringomyelia
Most cases of ALS are sporadic, arising in middle aged adults. However, a _______________________ mutation is present in some familial cases
Zinc-copper superoxide dismutase
[increased free-radical damage to neurons]
Degenerative disorder of cerebellum and spinal cord tracts; presents as ataxia (cerebellum) with loss of vibratory sense and proprioception, muscle weakness in lower extremities, and loss of DTRs
Friedreich Ataxia
Inheritance and mutation associated with Freidreich Ataxia
Autosomal Recessive
Unstable trinucleotide repeat (GAA) in frataxin gene
Friedreich ataxia presents in early childhood and is associated with what cardiovascular condition?
Hypertrophic cardiomyopathy
Meningitis = inflammation of the ___________
Leptomeninges (pia and arachnoid)
Meningitis is most commonly due to an infectious agent. What are the 3 most common infectious agents that cause meningitis in neonates?
Group B strep
E Coli
L monocytogenes
Most common infectious cause of meningitis in children and teens
N meningitidis
Most common infectious cause of meningitis in adults and elderly
Strep pneumo
Most common infectious cause of meningitis in nonvaccinated infants
H flu
T/F: Coxsackievirus and fungi are capable of causing meningitis
True
[fungal causes more common in immunocompromised]
At what level is a lumbar puncture performed? What layers do you pass through?
L4-L5 at level of iliac crest
Skin —> ligaments —> epidural space —> dura —> arachnoid
[Spinal cord ends at L2 but subarachnoid space and cauda equina continue to S2]
T/F: while performing a lumbar puncture, you pass through the pia mater
False
Complications are more commonly seen with bacterial meningitis. What are the major complications?
Death
Hydrocephalus, hearing loss, seizures
Cerebrovascular disease is a neurologic deficit arising due to cerebrovascular compromise, either due to ischemia (85%) or hemorrhage (15%). One type of ischemia is global cerebral ischemia, which may be due to what 4 conditions?
Low perfusion (atherosclerosis)
Acute decrease in blood flow (shock)
Chronic hypoxia (anemia)
Repeated episodes of hypoglycemia (insulinoma)
Clinical features of global cerebral ischemia depend on degree of ischemia, whether mild, moderate, or severe. A common example of mild global ischemia is with periodic hypoglycemia due to insulinoma. With moderate global ischemia, it is common to get infarcts in watershed areas, leading to damage to highly vulnerable regions. What are the 3 major “highly vulnerable regions” that may be affected?
Pyramidal neurons of the cortex (layers 3, 5, and 6 of the cortex — see cortical laminar necrosis)
Pyramidal neurons of the hippocampus
Purkinje layer of the cerebellum (see cerebellar signs)
What is the difference between an ischemic stroke and a TIA?
Ischemic stroke = regional ischemia that results in focal neurologic deficits for >24 hours
TIA = Symptoms <24 hours
3 ways in which you can develop an ischemic stroke
- Thrombosis —> pale infarct
- Embolism —> hemorrhagic infarct
- Lacunar stroke
Describe pathogenesis of a thrombotic stroke
Rupture of atherosclerotic plaque; usually develops at branch points
Results in a PALE infarct at the periphery of the cortex
Describe the pathogenesis of an embolic stroke
Due to thromboemboli; most common source is left side of heart
Usually involves the middle cerebral artery (classically in the setting of afib)
Results in a HEMORRHAGIC infarct at the periphery of the cortex
A lacunar stroke occurs secondary to ______ ________, and most commonly involves the ________ vessels
Hyaline arteriosclerosis; lenticulostriate
Ischemic stroke leads to _____ necrosis. ____ ________ are an early finding on microscopy. Neutrophils, microglial cells, and granulation tissue then ensue. The result is a fluid-filled cystic space surrounded by ______ (reactive astrocytes lining cystic space)
Liquefactive; Red neurons; gliosis
Intracerebral hemorrhage = bleeding into the brain parenchyma. This is classically due to what?
Rupture of Charcot-Bouchard microaneurysms (complication of HTN)
Intracerebral hemorrhage is classically due to rupture of Charcot-Bouchard microaneurysms as a complication of HTN. The most common site is the _____ _____; clinically presents with headache, nausea, vomiting, and eventual coma
Basal ganglia
Subarachnoid hemorrhage = bleeding into subarachnoid space. Presents as sudden headache with nuchal rigidity. Lumbar puncture shows _________
Xanthochromia
[yellow tinge to CSF due to bilirubin breakdown products]
Most common cause of subarachnoid hemorrhage
Rupture of berry aneurysm
The most common cause of a subarachnoid hemorrhage is rupture of a berry aneurysm, which is a thin-walled saccular outpouching that lacks a ______ layer, most frequently located in _______________
Media; anterior circle of willis (branch points of anterior communicating artery)
2 conditions classically associated with berry aneurysms
Marfan
ADPKD
Epidural hematoma = collection of blood between dura and skull. This is often due to fracture of __________ with rupture of the ________.
Presents with a ______-shaped lesion on CT. Note that a lucid interval may precede neurologic signs, and _______ is a lethal complication
Temporal bone; middle meningeal artery
Lens; herniation