Anatomy Flashcards
What sensory modality is most likely to be damaged in acceleration/deceleration (MVA) injuries to the brain?
The sense of smell. Olfactory bulbs and nerve lie underneath the frontal lobe and are often damaged in these accidents.
( Olfaction is also the only modality that bypasses the thalamus and anosmia can be a sign of early parkinsons)
Where is the lesion in a patient that presents with marked ptosis, dilated pupil and the eye deviated downwards and outwards.
Occulomotor nerve (Innervates all of the eye muscle except for the lateral rectus and the superior oblique. It also controls the levator palpebrae superioris, contains parasymp. fibers that constrict the pupil)
A third nerve palsy can be a symptoms of an aneurysm of what vascular structure?
Ipsilateral Posterior Communication Artery
Patient present with double vision with head tilted to one side, where is the pathology localized to ?
Trochlear nerve ( Innervates the superior oblique and when damaged causes vertical diplopia and patient compensate by tilting the head towards the shoulder on the unaffected side)
This nerve is most commonly damaged when there increased intracranial pressure
Abducens nerve ( Innervates lateral rectus. Patient cannot abduct when this nerve is damaged. When damaged due to a brainstem lesion often presents with facial weakness)
A patient with an inability to move left eye associated with a fixed dilated pupil and ptosis, numbness on the upper and middle part of the his face points to a lesion where?
Cavernous sinus ( CN III, IV, VI, V1 , V2 and the internal carotid artery all pass through the cavernous sinus. Can be caused by mucormycosis in diabetics, Tolosa-Hunt syndrome is a idiopathic granulomatous disease of the cavernous sinus)
What are some symptoms associated with pineal gland tumors ?
- Can be clinically silent until they affect the midbrain and cause visual symptoms, primary disturbance of upgaze, and at times disruptions of circadian rhythms.
When someone has a stroke affect the left frontal lobe their eyes will deviate to which side?
The left side ( Strokes look at the Same Side. In this case the left frontal eye field is infarcted and not functional, so there is unopposed action of the right frontal eye field which cause the eyes to deviate to the left)
When a patient has a seizure focus originating in their left frontal lobe which side will their eyes deviate to?
The right side ( Seizures look at the opposite side. In this case the seizure = hyperactivity of the left frontal eye field which will drive the eyes to the right)
What are the hallmarks of a horner’s syndrome ?
- Mild Ptosis, Miosis ( constricted pupil) and anhydrosis ) It is due to a lesion in the sympathetic pathway and is common in carotid artery dissection due to the fact that the sympathetic fibers run along the carotid, also seen in Wallenberg syndrome)
What is an internuclear opthalmoplegia? Where does the lesion localize to? In what condition is this most commonly seen?
INO: characterized by a failure to adduct one eye while having nystagmus in the opposing abducted eye. This is due to a lesion in the medial longitudinal fasciculus on the same side as the eye that cannot adduct. This is most commonly seen in Multiple Sclerosis. MLF connects the abducens nerve on side with the occulomotor nerve on the other side which allows for simultaneous activation of the medial and lateral rectus and preserves conjugate gaze.
Blurry vision and pain with eye movement are symptoms of what disease process ? Treatment?
-Optic neuritis ( Patients can loss color vision particularly color red.)
- Steroids ( solumedrol) is used to help patients with optic neuritis recover more rapidly
relapses can be treated with plasmaphoresis.
Explain an afferent pupillary defect.
An afferent pupillary defect is cause when there is a dysfunction in the CN2. Usually when light is swung from one eye to the other, both pupils will constrict. In afferent pupillary defect, due to the patient’s inability to perceive light in the affected eye, when light is shone in that eye it paradoxically dilates instead of constricts but when light is swung to the unaffected eye both eyes will constrict. In regularly lighted room, both pupils are equal.
What is the risk of developing MS most closely correlated with?
The number of lesions in the brain MRI. ( Older lesions on T1 are hypointense and appear as black holes and are evidence of axonal damage.
MS is associated with a deficiency in what vitamin ?
Vitamin D ( also associated with worsening symptoms in the heat, and with decrease incidence as you get closer to the equator)
What is the diagnostic criteria for MS?
Having 2 or more attach with clinic evidence or supportive evidence including typical MRI or oligoclonal bands in the CSF.
What are the DMD used to treat MS?
- Inteferons: Avonex, Rebif, Betaseron. ( injection)
- Glatiramer Acetate : Copaxone
- Natalizumab: Tysabri ( monthly infusion, monoclonal antibody prevents T-cell from crossing BBB. associated with PML)
- Fingolimod: Gilenya : Oral med
- Teriflunimode : Aubagio : Oral
- Dimethyl Fumerate : Tecfidera.
Neuromyelitis optica
- Devic’s disease: A demyelinating illness characterized by optic neuritis ( often b/l), transverse myelitis with MRI evidence of a contiguous spinal cord lesion 3 or more segments in length, brain MRI non-diagnostic for MS and NMO-IgG seropositivity. The IgG is directed against astrocytes on BBB and is generally more severe than MS
- may have intractable hiccups due to lesions in area postrema in medulla
Tx for NMO
- oral immunosuppression. Not MS tx: may make this worse
Bitemporal hemianopsia is caused by lesion where?
- Optic chiasm ( eg pituitary tumor compressing)
Where does monoccular blindness localize to?
- Optic nerve of that eye
Where does a homonymous hemiamposia localize to?
- Optic tract.
- right homonymous hemianopsia = left optic tract and vice versa
Where does a quandrantanopia localize to?
- Optic radiations: upper quandranopias localize to temporal lobe optic radiations
- lower quadrantanopias localize to parietal lobe.
- right quadrant = left side
Where does a homonymous hemianopsia with macular sparing localize to?
- Lesion in the occipital lobe.
Right visual field defect = left sided.
trigeminal neuralgia
- presents as a brief severe shock-like pain over the division of the trigeminal nerve on the face.
- can be triggered by mild stimuli like brushing teeth
- can be presenting sym of MS or due to vessel touching the nerve root
TX of Trigeminal neuralgia
- Carbemazepine
- Surgery can be used if it is due vessel compression
Trigeminal nerve
- ## originates in the pons but descends into the lower brainstem to medullary lesions can cause loss of sensation to face
Bell’s Palsy
- Facial nerve palsy: facial droop, inability to close eyes or scrunch forehead.
Can lead to hyperacusis due to lose of innervation of the stapedius muscle ( loss of taste in anterior 2/3 of tongue) - b/l facial nerve palsy;s associated with lyme disease
- Steroids and acyclovir against herpes can be beneficial if taken early
Ramsay-hunt syndome
- Herpes zoster infection of facial nerve p/w painful rash in the ear canal and nerve dysfunction.
Conductive hearing
- Due to damage of the ossicles
- will hear vibrations louder in affected ear during weber’s test
- will hear sound louder on bone than in air in Rinne’s test
Sensorineural hearing
- Due to damage to cochlea or CN8
- Weber’s test: sound louder in the unaffected ear
- Rinne’s test: air conduction will be louder than bone conduction
Ménière’s disease
- episodes of unilateral hearing loss
- severe episodes of vertigo
- tinitus
- a sense of fullness in ear
tx: salt restriction and diuretics caused by rupture of the membranous labyirnths
Benign Positional Vertigo
- Provoked by changes in head position
What meds can cause tinnitus
- Aspirin,
- aminoglycosides: mycin
- loop diuretics ( furosimide)
- cisplatin, carboplatin
Vestibular neuritis
- unilateral vestibular dysfunction may be associated with nausea, vomiting and previous upper respiratory react infections
Labyrinthitis
- unilateral vestibular dysfunction may be associated with nausea, vomiting and previous upper respiratory react infections
- associated with hearing loss and tinnitus
Which way does the tongue deviate with CN12 lesions
- To the side of the lesion
reticular formation
throughout the brainstem involved in motor control, sleep and consciousness, pain modulation and habituation
Central pontine myelinolysis
Demyelinating disorder that occurs when hyponatremia is corrected to rapidly leading to changes in cell osmolarities
- Alcoholics, chronically malnourished and medically ill patients
- p/w coma, acute quadraparesis, locked-in syndromes and
What kind of findings do brainstem lesion produce?
Crossed:
- Cranial nerve findings on the side of the lesion and motor and sensory findings opposite to the lesion.
- signs: dizziness, vertigo ataxia nausea, imbalance, double vision, nystagmus, dysarthria, dysphagia
Cervical spondylosis
legs crossing in front of each other ( scissored gait)
- mild weakness of hip flexors
- brisk reflexes, b/l up going toes
Where do expect pain and temperature abnormalities to begin on the body in someone with a spinal cord lesion
- one or two segments below the lesion
- spinothalamic tract decussates a few levels above where it enters the spinal cord
Upper motor neuron signs
hyperreflexia, increased tone , spasticity, babinski/hoffmans.
lower
decreased tone, decreased reflexes, atrophy, fasciculations
Brown-sequard syndrome
- weakness on the same side as lesion
- loss of proprioception and vibration on the same side
- loss of pain and temperature sense on the opposite side
Central cord
Shawl distribution
- Loss of pain and temp in the upper extremities b/l
- weakness in the upper extremities b/l
- can be due to syrinx/ syringomyelia
anterior cord syndrome
- Loss of pain and temperature in in the legs b/l
- weakness b/l
- preservation of proprioception and vibratory sense.
- occurs during occlusio of the anterior spinal artery ( AAA surgery)
Posterior cord syndrome
- loss of proprioception.
- pt have intense pain and burning sensations in their limbs
Cord transections
- weakness and loss of all sensation below the lesion.
Cauda equina syndrome
- Ten nerve pair fibers ( 5 lumbar, 5 sacral and 1 coccygeal). Caused by compression of these nerves ( herniated disk L4-L5 or L5-S1),
- numbness in the genitals, buttocks and anus due to compression of the sacral nerve roots
- lower extremity weakness often asymmetrical
- decreased knee reflexes
- bowel and bladder retention though this happens later
Conus medullaris syndrome
- caused by lesion at L1/L2
- weakness is symmetrical
- knee reflexes are preserved
- bowel and bladder incontinence develop early as does impotence
Amyotrophic lateral sclerosis
Caused by degeneration of the anterior horn cells ( motor neurons of the brain, cranial nerve nuclei and spinal cord)
What tx for ALS is should to extend survival
Riluzole
b 12 deficiency
Causes subacute combined degeneration of the spinal cord: damage of the corticospinal tract and dorsal columns
- can p/w psych symptoms and normal b12 have to check homocysteine and methylmalonic acid.
- Seen in pt with pernicious anemia, post gastric
- Nitrous oxide interferes with B12 metabolism and can cause this
Presentation of cerebellar dysfunction
- Ataxia: unsteadiness or incoordination of limbs, posture and gait
- hypotonia: normal resting muscle tension is reduced
- tremor: intention tremor of the hand on purposive movement
- Gait: legs are wide apart
- Ocular motor abnormalities: saccadic dysmtria, impaired fixation, various forms of nystagmus
- Scanning speech: abnormal pauses between words
What causes cerebellar dysfunctoin
- toxins: dilantin, ETOh
- neurodegenerative disorder: olivopontocerebellar atrophy
- paraneoplastic: GYN cancer/ anti-YO
- spinocerebellar ataxias
- Vascular disorders
- symptoms occur ipsilateral to the lesion
