Flashcards in Neuro3 Deck (47):
Attributes of lower motor neuron lesion
--loss of deep tendon reflexes
--fibrillation potentials seen on EEG
--loss of voluntary movement
Lesion of the pyramidal decussation would clinically manifest as what?
Bilateral upper motor neuron symptoms, as this is where the corticospinal (upper motor) neurons cross
What does the locus ceruleus synthesize; what is its function?
This nucleus synthesizes norepinephrine, and is involved in the control of cortical activation (arousal).
What structure is contained in the floor of the third ventricle?
What structure is located in the floor of the fourth ventricle?
The area postrema, which is part of the medulla?
What is the area postrema?
The area postrema contains the chemoreceptor trigger zone, and is the area of the brain that controls vomiting
Noise-induced hearing loss is mediated by damage to what structure?
damage to hair cells in the organ of corti
These cells can be damaged by trauma from very loud noises, or by ototoxic drugs
What is presbycusis?
Age-related hearing loss.
results of loss of hair cells at the base of the cochlea, leading to high frequency hearing loss.
How can a sudden, extremely loud noise produce hearing loss?
By rupturing the tympanic membrane
Anatomy and function of the middle ear
Air-filled space with three bones called the ossicles: malleus, incus, stapes.
The ossicles conduct and amplify sound from the eardrum to the inner ear.
What would posterolateral herniation of an intervertebral disc cause injury to?
(1) Spinal cord
(2) Spinal root
(3) Anterior ramus
(4) Posterior ramus
The spinal root
This herniation results in the nucleus pulposus occupying the space of the intervertebral foramen, which contains the spinal nerve root.
The anterior (ventral) and posterior (dorsal) rami are found *lateral* to the intervertebral foramen.
The spinal cord is located within the vertebral canal. A *posterior* herniation of the nucleus pulposus would compress the spinal cord
What nerve innervates the cricothyroid muscle?
The external branch of the superior laryngeal nerve
What are negri bodies pathognomonic for?
What are the most frequent neoplasms that would present with blocking of the fourth ventricle, and a non-communicating hydrocephalus?
Medulloblastoma and ependymoma
What are the childhood primary brain tumors?
--pilocytic (low-grade) astrocytoma
18 year old comes to the physician because of difficulty walking. Two days ago he experienced weakness in both of his legs, and now he is unable to walk. Physical exam shows symmetric hyporelfexia of the lower extremities. Two weeks prior, he had an upper respiratory tract infection that was treated with azithromycin. What is the likely diagnosis?
How does Guillan-Barre syndrom classically present?
With symmetric, ascending, bilateral (motor) weakness and hyporeflexia that starts in the lower extremities following an infection.
Sensory symptoms can occur, but motor symptoms predominate
What is Guillan-Barre also known as?
Acute Inflammatory Demyelinating Polyradiculopathy
With what infections is Guillan-Barre associated?
What is thought to be the pathophysiologic mechanism of GBS (Guillan-Barre Syndrome)?
Autoimmune attack of peripheral myelin due to molecular mimicry, inoculation (infection), and stress.
What is the feared complication of GBS?
GBS can progress to complete paralysis and respiratory failure. Respiratory support is critical until recovery
Patient presents with "worst headache of my life"; MRI shows a berry aneurysm. What is the likely diagnosis?
What genetic disorders are associated with development of a berry aneurysm?
Connective tissue disorders:
Also associated with:
Adult Polycystic Kidney Disease (ADPKD)
--Rupture of middle meningeal artery after skull fracture
--lucid interval before loss of consciousness
What's the likely diagnosis?
--Rupture of bridging veins
What's the likely diagnosis?
How would you treat GBS?
--plasmapheresis (remove autoantibodies)
--IVIG (attach to/inhibit autoantibodies)
Why are connective tissue disorders associated with the development of berry aneuryms?
Because these disorders can cause weakening of the blood vessel wall
What are the 5 types of generalized seizures?
What is the general definition of general seizures?
Diffuse; initially involve both hemispheres
What is the general definition of partial (focal) seizures?
They affect 1 area of the brain
--A brief loss and return of consciousness
--EEG shows generalized spike and slow-wave changes
--no postictal state
--no loss of muscle tone
Absence seizure (petit mal)
*absence seizures are characterized by blank stares and absence of any change in position
--Transiently increased muscle tone: quick, repetitive jerks.
Alternating stiffening and movement (relaxation)
Tonic-clonic (grand mal) seizure.
In addition to stiffening and relaxation, what other symptoms are tonic-clonic seizures associated with?
--loss of consciousness
--loss of bladder/bowel function
--an extended postictal phase, during which the patient slowly recovers
Stiffening in a child
Patient suddenly loses consciousness and falls to the floor with a loss of consciousness. Bystanders wonder if the patient has fainted.
commonly mistaken for fainting
What is the postictal state?
The altered state of consciousness after a seizure
usually lasts between 5 and 30 minutes
What is epilepsy?
A disorder of recurrent seizures
*note: febrile seizures are not epilepsy
What is status epilepticus?
continuous seizure for >30 minutes or recurrent seizures without gaining consciousness between seizures for >30 minutes.
This is a medical emergency
What is the most common site/origin of focal seizures?
medial temporal lobe
What often precedes a focal seizure?
a seizure aura
What is the difference between a simple partial and complex partial seizure
In a simple partial seizure, consciousness is intact; in a complex partial seizure, consciousness is impaired
What is the blood supply for Wernicke's area?
(inferior division of) the middle cerebral artery
Where, specifically, is Wernicke's area located in the cerebral cortex?
In the posterior part of the superior temporal gyrus (of the language-dominant hemisphere--typically the left)
What is a common associated feature (comorbidity) of Wernicke's aphasia (temporal lobe damage)
contralateral upper right quadrantanopia
This is because Meyer's Loop, is located in the temporal lobe.
What would result from a lesion to the arcuate fasciculus?
The arcuate fasciculus connects Wernicke's and Broca's areas. A lesion to this area would result in a conduction aphasia, which is characterized by a striking inability to repeat, while language comprehension and output are largely preserved.