Neurology Flashcards
Diabetic CN III Neuropathy
- Ischemic deficit (not compression) affecting somatic fibers only.
- CN III has both somatic and parasympathetic fibers which have different blood supplies.
Somatic fibers: innervates superior, inferior, and medial rectus, inferior oblique, and levator palpebrae
Parasympathetic fibers: innervates the sphincter of the iris and ciliary muscle —–> fixed, dilated pupil and loss of accomodation
Symptoms: “down and out” gaze, ptosis (unopposed action of the lateral rectus and superior oblique)
- Intact pupillary response and accommodation.
- Compression neuropathy affects all functions.
Todd’s palsy
preceded by a focal motor seizure
Carotid artery thrombosis
- Most commonly affects the middle cerebral a. —> contralateral hemiparesis and hemianesthesia
Lacunar stroke - pure motor hemiparesis
- Lacunar infarction in the posterior limb of the internal capsule
Presentation: unilateral motor deficit (face, arm, and to a lesser extent leg), mild dysarthria
- No loss of sensory, visual, or higher cortical function
Lacunar stroke - pure sensory stroke
- Stroke in the ventroposterolateral nucleus of the thalamus.
Presentation: unilateral numbness, parasthesias and hemisensory deficit involving the face, arm, trunk, and leg
Lacunar stroke - ataxic hemiparesis
Lacunar infarction of the anterior limb of the internal capsule
Presentation: weakness that is more prominent in the lower extremity, along with ipsilateral arm and leg incoordination
Lacunar stroke - dysarthria-clumsy hand syndrome
Lacunar stroke at the basis of the pons
Presentation: hand weakness, mild motor aphasia
- NO sensory abnormalities
Migraine treatment and prophylaxis
Antiemetics: prochlorperazine, chlorpromazine, and metaclopramide
- NSAIDS or triptans if started early into the headache.
Prophylaxis: amitriptyline, propranolol
Basal ganglia hemorrhage
Symptoms: contralateral hemiparesis and hemisensory loss, homonomyous hemianopsia, gaze palsy
Cerebellar hemorrhage
- Usually NO hemiparesis
- Facial weakness, ataxia, nystagmus, occipital headache, and neck stiffness
Thalamic hemorrhage
Symptoms: contralateral hemiparesis and hemisensory loss, non-reactive miotic pupils, upgaze palsy, eyes deviate towards hemiparesis
Cerebral lobe hemorrhage
Symptoms: Contralateral hemiparesis (frontal lobe), contralateral hemisensory loss (parietal lobe), homonymous hemianopsia (occipital lobe), eyes deviate away from hemiparesis, high incidence of seizures
Pons hemorrhage
Symptoms: deep coma and total paralysis within minutes, pinpoint reactive pupils
Essential tremor
- Bilateral action tremor of the hands, usually without leg involvment
- Possible isolated head tremor without dystonia(involuntary repetitive movement)
- Relieved with alcohol
- no other neurologic defecits.
Treatment: propranolol; second-line: primidone and topiramate
Parkinson’s disease tremor
- resting tremor (4-6Hz) that decreases with voluntary movement
- Usually involves legs and hands
- facial involvement less common
- May progress to involve other areas of the body
Tetrad: resting tremor, rigidity, postural instability, and bradykinesia
- Tremor worsens when performing mental tasks and disappears with movement
- Due to progressive loss of dopaminergic neurons in the basal ganglia.
Cerebellar tremor
- Usually associated with ataxia, dysmetria (lack of accuracy during voluntary movement), or gait disorder
- Tremor increases steadily as hand reaches its target
-Can see postural, action, or intention tremors
Physiologic
- Low amplitude (10-12Hz), not visible under normal conditions
- acute onset with sympathetic activity (drugs, hyperthyroidism, caffeine)
- Usually worse with movement and can involve the face and extremities
Brain death
- Absent cortical and brainstem function
- Spinal cord may still be functioning, so DTR can still be present.
- HR becomes invariant due to loss of vagal control.
Status epilepticus
- single seizure lasting longer than 30 mins
- Brains that have seized for >5 minutes are at risk of permanent injury due to excitatory cytotoxicity —-> cortical laminar necrosis
Neurofibromatosis type 2
- mutation in tumor suppressor gene on chromosome 22
- Subcutaneous neurofibromas, cafe-au-lait spots, deafness due to acoustic neuromas
severe variant - Wishart - framshift or nonsense mutations
milder variant - Gardner - missense or splice-site mutation
Primary sclerosing cholangitis
Clinical features: fatigue, pruritis
- 90% of pts have underlying IBS, mainly ulcerative colitis
Labs: Aminotransferases
Ascited Fluid Characteristics
Neutrophils: 250 peritonitis (secondary or spontaneous)
Total protein: >or= 2.5 (high-protein ascites) - CHF, constrictive pericarditis, peritoneal carcinomatosis, TB, Budd-Chiari syndrome, fungal
or=1.1 (indicates portal hypertension) - cardiac ascites, cirrhosis, Budd-Chiari syndrome
Blood supply of the brain
Common carotids —> internal carotids —> opthalmic artery and then anterior and middle cerebral arteries
Subclavian arteries —> vertebral a. —> posterior inferior cerebellar a., then anterior spinal a., then basilar a. —> anterior inferior cerebellar a., then pontine a. —> superior cerebellar a., then posterior cerebral a. which connect to circle of willis vis posterior communicating a.
Middle cerebral artery supply
lateral surface of the frontal, parietal, and upper temporal lobes, genu and posterior limb of internal capsule, majority of the basal ganglia, proximal parts of the visual radiations as they emerge from the lateral geniculate nucleus of the thalamus and course in Meyer’s loop
Anterior cerebral artery supply
medial surface of the frontal and parietal lobes (motor and sensory areas for pelvis and lower limbs), superior inch of the frontal and parietal lobes, anterior 4/5 of corpus callosum, anterior limb of internal capsule
Posterior cerebral artery supply
inferior temporal lobe and occipital pole
Anterior cerebral artery occlusion deficits
spastic paresis and anesthesia of contralateral lower limb
Note: if bilateral, urinary incontinence can occur
- if anterior corpus callosum is involved, a transcortical apraxia of the left limbs may occur (disconnection of left hemisphere’s (language dominant) from motor cortex of right hemisphere)
Apraxia
Inability to perform particular purposive actions
Middle cerebral artery occlusion deficits
- spastic paresis of the contralateral lower face and upper limb and anesthesia of the contralateral face and upper limb
- Aphasia can occur when left MCA is affected and left-sided neglect can occur when right MCA is affected
- Contralateral superior quadrantanopsia w/ occlusion of the branches supplying Meyer’s loop.
Vertebral a. course
through transverse processes of upper 6 cervical vertebrae; enters posterior fossa after passing through foramen magnum
Anterior spinal a. supply
ventrolateral 2/3 of cervical spinal cord and ventromedial part of medulla
PICA supply
cerebellum and dorsolateral medulla
Labyrinthine a. supply
branch of the basilar a. that follows the course of CN VIII; supplies the inner ear
AICA supply
part of pons, anterior and inferior cerebellum
Superior cerebellar a. supply
rostral pons and superior cerebellum
Pontine branches supply
pons via paramedian and circumferential branches
PCA supply
midbrain
Midbrain CNs
III and IV
Upper pons CNs
V
Lower pons CNs
VI, VII, VIII
Upper medulla CNs
IX, X, XII
Medial medullary syndrome
Occlusion of the vertebral a. or anterior spinal a.
Localizing sign
- CN XII - ipsilateral paralysis of half the tongue w/ atrophy (tongue deviates towards the lesion)
Affected nerve tracts
- medial lemniscus - contralateral deficit of proprioception and touch, pressure, and vibratory sensation in limbs and body
- pyramid (corticospinal tract) - contralateral spastic hemiparesis of both limbs
Lateral medullary syndrome (Wallenberg)
Occlusion of PICA
Localizing CNs
- vestibular or cochlear parts of CN VIII - may produce nystagmus, vertigo, N/V (w/ vestibular nystagmus, the fast component will be away from the side of the lesion)
*Lesions of the cochlear nucleus or auditory nerve produce an ipsilateral sensorineural hearing loss.
- CN IX - diminished or absent gag reflex
-CN X - dysphagia or hoarseness, palate will droop on affected side and the uvula will deviate away from the side of the lesion
- spinal nucleus and tract of CN V - loss of just pain and temperature on ipsilateral side of half the face (touch and corneal blink reflex will be intact)
Affected nerve tracts
- spinothalamic tracts - pain and temperature deficit in contralateral limbs and body
- descending hypothalamic fibers - ipsilateral Horner syndrome
* If solitary nucleus is affected, taste sensations may be altered
Medial Pontine Syndrome
occlusion of the paramedian branches of the basilar a.
- CN VI - internal strabismus of the ipsilateral eye (diplopia on lateral gaze to the affected side)
- Corticospinal tract - contralateral spastic hemiparesis of both limbs
- Medial lemniscus may be affected - contralateral deficit of proprioception and touch pressure and vibratory sensations in the limbs and body.
- CN VII may be affected if it extends laterally
- Long tract signs are the same as in medial medullary syndrome but the CN signs localize the lesion
Upper motor neuron
Due to spinal cord lesions
Myesthenia gravis
- AutoAbs against acetylcholine receptor on post-synaptic membrane
Signs and symptoms: - extraocular muscle weakness (ptosis and diplopia), bulbar muscle weakness (jaw fatigue with chewing and dysarthria with talking).
- symmetrical proximal weakness of the extremities (upper more than lower), neck (flexors and/or extensors), and bulbar muscles (dysarthria/dysphagia)
- Normal reflexes, muscles bulk/tone, sensory function and autonomic function.
Diagnosis: CPK is normal differentiating it from primary muscle problem
- Associated with the presence of a thymoma —> always order CT of the chest bc thymoma can sometimes be invasive.
- Sometimes associated with thyroid disease —-> ultrasound can be helpful.
Amyotrophic lateral sclerosis
- Affects distal muscles more
- sensory abnormalities and ocular deficits are usually absent
Mononeuropathies
- Affect both motor and sensory function of single nerve
Multiple sclerosis
- Autoimmune CNS demylenating disease
- Upper motor neuron signs
- Oligoclonal IgG bands in the CSF with normal opening pressure, protein, and cell count.
Treatment of acute exacerbations:
- IV steroids in symptoms are severe.
- Mild sensory symptoms do not require steroids.
- Steroids do not prevent future attacks or prevent progression.
Reduce frequency of acute exacerbations:
- interferon, plasmapheresis, cyclophosphamide, IV immunoglobulin, glatiramer acetate
Polyneuropathies
- in diabetes mellitus
- vitamin B12 deficiency
- Guillain-Barre syndrome
- Chronic inflammatory demyelinating polyneuropathy
Signs and symptoms: reduced or absent reflexes, parathesias, motor and sensory symptoms of both upper and lower extremities, but not usually bulbar symptoms
Exertional heat stroke
Risk factors: obesity, certain medications (anticholinergics, antihistamines, phenothiazines, tricyclics)
Clinical manifestations: core temperature >104F AND CNS dysfunction (altered mental status, seizure, confusion, irritability)
- Additional organ or tissue damage (renal/hepatic failure, DIC, ARDS, coagulopathic bleeding)
Other possible signs and symptoms: dry or sweaty skin, hypotension, tachycardia, hyperventilation, diarrhea, cramps, ataxia
Management: rapid cooling: ice water immersion preferred, fluids, electrolyte correction, no role for antipyretic therapy
- Evaporative cooling is preferred in nonexertional heat stroke (elderly patients with comorbidities).
Heat exhaustion
> 104 F, but no CNS dysfunction
Multiple system atrophy (Shy-drager syndrome)
Degenerative disease
Characteristics:
- Parkonsonism
- autonomic dysfunction
- widespread neurological signs (cerbellar, pryamidal, LMN)
- Accompanied by bulbar dysfunction and laryngal stridor.
Treatment: anti-Parkinsonism drugs are ineffective; treated w/ intavascular volume expansion w/ fludrocortisone, salt supplementation, alpha adrenergic agonists, and constrictive garments on the lower body
Idiopathic orthostatic hypotension
- Degeneration of postganglionic sympathetic neurons
- Solely autonomic dysfunction.
Familial dysautonomia (Riley-Day syndrome)
Autosomal recessive condition found in Ashkenazi Jews
- autonomic dysfunction with severe orthostatic hypotension.
Chemotherapy-induced peripheral neuropathy
- symmetrical parasthesias of the fingers and toes, early loss of ankle jerk reflexes, loss of pain and temperature sensation, occasional motor neuropathy
- Commonly due to platinum-based meds (cisplatin), taxanes (paclitaxel), and vinca alkaloids (vincristine)
Allodynia
Perception of a normally innocuous stimulus as painful