Nervous Flashcards
Reye Syndrome
should be suspected in a young child w acute liver failure and encephalopathy after receiving aspirin for a virus-induced fever; aspirin in this setting is a mitochondrial toxin that leads to hepatic swelling, hyperammonemia, and diffuse astrocyte swelling (cerebral edema)
Trochlear nerve palsy
CN IV innervates the superior oblique muscle which causes the eye to internally rotate and depress while adducted; palsy is typically traumatic or idiopathic and presents w vertical diplopia that worsens when the affected eye looks down and toward the nose (ex: walking down the stairs)
selective serotonin reuptake inhibitors (SSRIs)
1st line antidepressant therapy (ex: sertraline); commonly associated with sexual dysfunction (about 50% of pts); physicians should routinely inquire about sexual dysfunction because it is a common side effect and may lead to non adherence
neural tube defects
failure of neural tube closure results in NTDs; folate deficiency is the greatest risk factor and meds that impair folate metabolism (ex: valproate) are associated w increased risk
migraines
migraines are episodic, unilateral throbbing HA associated with n/v and sensitivity to light; pathogenesis involves a genetic predisposition to increased cerebral excitability which leads to abnormal neuronal activation of trigeminal afferents and the release of calcitonin gene-related peptide, a vasoactive neuropeptide involved in the transmission of pain signals
embryonic origin of pituitary adenoma
pituitary adenoma is a benign tumor arising from the anterior pituitary and the most common cause of sella masses in adults; the anterior pituitary forms the surface ectoderm, one of the 3 tissues derived from the ectoderm (ex: surface ectoderm, neural tube, neural crest)
sphingolipidoses
Tay-Sachs disease is an AR disorder caused by B-hexosaminidase A deficiency which results in GM2 ganglioside accumulation in neuronal lysosomes; key clinical features include progressive neurodegeneration, an exaggerated startle reflex and a cherry-red macular spot
Pontine glioma
the nuclei of the vestibulococchlear nerve (CN VIII) are located in the pons; CN VIII conveys information about head position and movement and helps to stabilize the gaze during head movement; damage can lead to nystagmus
Holoprosencephaly
Holoprosencephaly is due to failure of the primitive forebrain (prosencephalon) to divide into the right and left hemispheres, resulting in a spectrum of brain and mid face abnormalities; trisomy 13 is the most commonly associated etiology
TMJ and hypersensitivity of the mandibular nerve
TMJ disorder is associated w dysfunction of the TMJ joint and hypersensitivity of the CN V3; this can result in pathological contraction of the pterygoid muscles and tensor tympani in the middle ear (ear pain/muffled hearing)
Neuroleptic malignant syndrome (NMS)
NMS is characterized by severe muscular ridigity, mental status changes, autonomic dysregulation and hyperthermia; dopamine antagonism, the MOA of most antipsychotics, has been implicated as a primary cause of NMS
“blowing” diastolic decrescendo murmur w bounding femoral and carotid pulses
aortic regurg; causes an increase in total SV w abrupt distention and rapid falloff of peripheral arterial pulses, resulting in wide pulse pressure; this leads to bounding peripheral pulses and head bobbing w each heartbeat
apolipoprotein E4 associated Alzheimer’s disease
early onset familial Alzheimer disease is associated w three gene mutations:
APP (chr 21)
Presenilin 1 and 2
late-onset apolipoprotein E4 genotype
abducens palsy
an expanding aneurysm is the cavernous portion of the internal carotid artery is most likely to initially cause HA and diplopia due to compressing or stretching of the abducens nerve (CN VI) as it runs next to the ICA in the cavernous sinus
Wilson’s disease - the putamen
Wilson’s disease can cause cystic degeneration of the putamen as well as damage to other basal ganglia structures; the putamen is located medial to the insula and lateral to the globus pallidus on coronal sections
Neural tube defects (NTDs)
NTDs most often occur when the neural folds fail to fuse in the region of the anterior and posterior neuropores; an open NTD allows leakage of alpha-fetoprotein and acetylcholinesterase into amniotic fluid, leading to elevated levels detected on amniocentesis
phrenic nerve stimulation in myasthenia gravis
progressively weakening diaphragmatic contractions during maximal voluntary ventilation w intact phrenic nerve stimulation indicate NMJ pathology (ex: MG) or abnormally rapid primary muscle fatigue
presenilin in Alzheimer’s
Orbital floor fractures
orbital floor fractures can result in entrapment of the inferior rectus muscle, which presents w vertical diplopia and restriction of upward movement; in addition the infraorbital nerve (V2) runs along the orbital floor and can be damaged, resulting in numbness and paresthesia of the upper cheek, lip and gingiva
Fragile X syndrome
results from unstable expansion of trinucleotide repeats (CGG) in the fragile X messenger ribonuceloprotein 1 (FMR1) gene; classic physical findings include dysmorphic facial features (long face, prominent jaw, protruding ears) and macroorchidism
Craniopharyngioma
Craniopharyngiomas are suprasellar tumors found in children and composed of calcified cysts containing cholesterol crystals; they arise from remnants of Rathke’s pouch, an embryonic precursors of the anterior pituitary
Myotonic dystrophy type 1
Myotonic dystrophy type 1 is due to a CTG repeat in the DMPK gene resulting in untranslatable mutant mRNAs; the mutant mRNAs form hairpin structures and accumulate in the nucleus, sequestering certain RNA-binding proteins and leading to aberrant splicing; non dividing cells of the brain, skeletal muscles and myocardium are particularly affected
peripheral facial palsy
CN VII exits the stylomastoid foramen and courses through the substance of the parotid gland where it divides into its 5 terminal branches innervating the muscles of facial expression; malignant tumors of the parotid gland often compress and disrupt the facial nerve and its branches causing ipsilateral facial droop
Scalp hematomas
subgaleal hemorrhage is a potentially fatal neonatal bleed that occurs during delivery when emissary veins between the dural sinuses and scalp are sheared; the accumulation of blood between the periosteum and galea aponeurosis presents w a diffuse, progressive, fluctuant scalp and neck swelling; massive blood loss can lead to shock and death if not promptly recognized
trigeminal neuralgia tx MOA
1st line tx is carbamazepine; inhibits neuronal high-frequency firing by blocking Na+ channels; carbamazepine can cause bone marrow suppression; therefore, CBC counts should be monitored periodically
anoxic brain injury
neuronal damage after hypoxic-ischemic injury is often related to the formation of ROS which mediate widespread cellular damage; therapeutic hypothermia decreases the formation of ROS species by decreasing cellular metabolism and slowing reperfusion
