Neurology Flashcards
Components of the brain
- Cerebrum (R & L cerebral hemispheres)
- Each hemisphere subdivided into lobes:
frontal, parietal, temporal, occipital - Diencephalon
- Brainstem (midbrain, pons, medulla)
- Cerebellum
- Deep brain nuclei
- Tracts, fascicles, commissures
PNS fxn
Connects CNS to muscles & glands
PNS components
- Cranial nerves & ganglia
- Spinal nerves & dorsal root ganglia
- Enteric nervous system
Frontal lobe
- Higher order cognition
- Motor planning, execution
- Speech (expression)
Parietal lobe
Somatosensation
Occipital lobe
Vision
Temporal lobe
- Audition
- Speech (reception)
- Hippocampus (memory)
Spinal cord components
- Ascending & descending tracts
- Gray matter
Gray matter vs white matter
- Gray matter = neuronal cell bodies
- White matter = neuronal axons
Cerebral cortex
- Extensive outer layer of gray matter of the cerebral hemispheres
- Largely responsible for higher brain fxns
Cerebellar cortex
Superficial gray matter of the cerebellum
Where do the 12 cranial nerves arise?
- Brain (I & II)
- Diencephalon
- Brainstem
How many spinal nerves attach to the spinal cord?
31 pairs:
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
Upper motor neurons
- Nerve cell bodies that lie in the cerebral cortex & in several brainstem nuclei
- Axons synapse w/ motor nuclei in the brainstem (for CNs) & in the spinal cord (for peripheral nerves)
- Babinski sign present
Lower motor neurons
- Nerve cell bodies in the spinal cord (anterior horn cells)
- Axons transmit impulses through the anterior roots & spinal nerves into peripheral nerves
- Terminate at the neuromuscular junction (interface btwn the nerve at the synaptic junction & the muscle fiber)
- Connect brainstem & spinal cord to muscle fibers (bringing UMNs to muscles)
- Axon terminates on an effector
What are the 3 motor pathways?
- Corticospinal tracts
- Basal ganglia system
- Cerebellar system
Through what 2 pathways does UMN control LMN?
- Pyramidal tract
- Corticospinal tract - Extrapyramidal tract
- Reticulospinal
- Vestibulospinal
- Tectospinal
- Rubrospinal tract
- Corticobulbar tract
- Corticorubral tract
- Olivospinal tract
Extrapyramidal tract
- Centers on the modulation & regulation (indirect control) of anterior (ventral) horn cells.
- Modulates motor activity w/out directly innervating motor neurons
- Can be involved w/ involuntary movements
Corticospinal tracts: Origin
Motor cortex of brain
- Travels into lower medulla –> crosses to contralateral side of the body –> synapses w/ anterior horn cells
Corticospinal tracts: Actions
- Mediates voluntary & complicated delicate movements by stimulating selected muscle actions, inhibiting others
- Inhibits muscle tone
Corticospinal damage
Diminished fxn below level of injury
- Affected limb becomes weak or paralyzed
- Skilled or delicate movements are poor when compared to gross movements s/a walking
- Other effects depend on whether the damage is in UMN or LMN
LMN fxn
- All voluntary movement depends upon excitation of LMN by UMN
- The only neurons that innervate skeletal muscle fibers
- Fxn as the final common pathway
- Final link btwn CNS & skeletal muscles
UMN lesions
- Damage above the crossover in the medulla –> motor impairment on contralateral side
- Damage below the crossover –> motor impairment on ipsilateral side
- Muscle tone is increased & deep tendon reflexes are exacerbated (due to loss of muscle tone inhibition)
LMN lesions
- Damage = ipsilateral motor impairment (weakness or paralysis)
- Muscle tone & reflexes are decreased or absent
- Atrophy & fasciculations present
Basal ganglia system
- Complex motor pathway
- Includes pathways btwn cerebral cortex, basal ganglia, brainstem & spinal cord
Basal ganglia actions
Maintain muscle tone & control body movements, esp. gross automatic movements s/a walking
Basal ganglia damage
- Does not result in paralysis but causes:
1. Changes in muscle tone (usually increased)
2. Involuntary muscle movements
3. Disturbances in posture & gait
4. Slow or absent automatic movements (bradykinesia)
Cerebellar actions
- Coordinates motor activity
- Maintains equilibrium
- Controls posture
Cerebellar damage
- Impairs coordination, gait & equilibrium
- Decreases muscle tone
What do sensory impulses participate in?
- Reflexes
- Conscious sensation
- Calibration of body position
- Regulation of internal autonomic fxns
*BP, HR, RR
Sensory pathway fxn
- Relay impulses from skin, muscles, viscera through peripheral nerves & posterior roots to enter spinal cord
- Once inside spinal cord, impulses are transmitted to sensory cortex via:
1. Posterior column pathway
2. Spinothalamic tracts
Spinothalamic tracts
- Sensory afferent fibers conducting light touch, pain, & temperature pass into the posterior horn of spinal cord & synapse w/ secondary neurons
- Secondary neurons cross to contralateral side –> travel upward in the spinothalamic tracts to the thalamus
What does the thalamus do?
Transmits sensory impulses to cerebral cortex
Posterior columns
- Sensory afferent fibers conducting discriminative touch, proprioception, & vibration pass directly into posterior columns of the spinal cord & don’t synapse w/ secondary neurons until they reach the medulla
- Secondary neurons cross to contralateral side & travel to the thalamus
Spinothalmic tracts: Neurons (3)
- 1st enters spinal cord
- 2nd decussates in spinal cord & travels to thalamus
- 3rd conveys info from thalamus to specific area of cortex
Posterior columns: Neurons (3)
- 1st enters cord & ascends ipsilaterally
- 2nd decussates in medulla & travels to thalamus
- 3rd conveys info from thalamus to specific area of cortex
Spinocerebellar tracts
- Conveys info re: unconscious proprioception to cerebellum
- Proprioceptive to cerebellum
- Posterior & anterior
- Ipsilateral (does not decussate)
Spinocerebellar tract: Neurons (2)
- Primary neuron from receptor to spinal cord
- Secondary neurons from spinal cord to cerebellar cortex
Myelopathy
Any functional disturbance &/or pathological change in the spinal cord
- UMN lesion
How is myelopathy characterized?
- Increased tone, elevated reflexes
- Proprioception changes
- Romberg
- Crossed findings (sensory & motor)
Radiculopathy
Disease of the nerve root
- LMN lesion
- Involve injury from pressure or other mechanical causes
- Cervical roots C5-8 innervate upper extremities
- Lumbosacral roots L3-S1 innervate lower extremities
How is radiculopathy characterized?
- Loss of reflexes
- Lancinating pain
- Focal distributed weakness
Mononeuropathy
Damage to a single nerve or nerve group
- LMN lesion
How is mononeuropathy characterized?
Loss of movement, sensation, &/or other fxn
Examples of mononeuropathy
- Carpal tunnel syndrome: median nerve compression
- Ulnar nerve compression
Median nerve compression
- Sensory loss – 1st 3 ½ digits
- Motor loss – thenar (abductor pollicus brevis, opponens)
- Pain – nocturnal in 1st 3 ½ digits & forearm
Ulnar nerve compression
- Sensory loss - 4th & 5th digits
- Motor loss - hypothenar (abductor digiti minimi, 1st dorsal interosseous)
- Pain - 4th & 5th digits & tenderness at elbow
Romberg test
- Tests position sense (posterior columns)
- Check Romberg before gait testing to avoid a fall
1. Instruct pt to stand w/ feet together & eyes open
2. Ask him/her to close eyes for 30-60 secs w/out support - Stand close to pt to prevent fall
- Loss of balance = + Romberg = ataxia due to posterior column disease
Ataxia due to cerebellar disease
Results in difficulty standing w/ feet together, whether eyes or open or closed
Pronator drift
- Test for contralateral corticospinal tract lesion (UMN)
1. Pt should stand w/ arms extended outwards & palms up for 20-30 secs w/ eyes closed (pronation & downward drift of arm = +) - Detects subtle contralateral UMN lesion
Mental status exam (MSE)
- Begins when you 1st meet & continues throughout exam
- Assessing “JOMAC” : Judgement, Orientation, Memory, Affect, Cognition
- Formal testing only indicated when deficits are present
MSE: Behavior & appearance
- Grooming, dress, hygiene
- Mood
- Affect
MSE: Orientation
- Name
- Place
- Time
- Situation
MSE: Level of consciousness
- Alert, lethargic, stuporous, comatose
- Responsive vs. non-responsive
MSE: Recent memory
Recall 3 random words after 1 min
MSE: Remote memory
Ask about well known events, dates, & locations
MSE: Attention span/calculation
- Serial 7s
- Spell WORLD (forwards & backwards)
Cerebellar examination: Coordination
- Assess for overall balance, equilibrium, & coordination of movement
- Finger to nose
- Heel to shin
Finger to nose
- Pt alternates touching the examiner’s finger, then his/her own nose
- Detects dysmetria
Heel to shin
- Pt slides his/her heel of 1 foot down shin of other leg slowly & smoothly
- Instruct pt to repeat 1 time, then switch legs in order to test cerebellar fxn bilaterally
Cerebellar examination: Rapid alternating movements (RAMs)
Observe for speed & coordination while assessing 1 of the following:
- Rapid pronation & supination of forearms
- Touching fingertips to thumb
- Tapping feet
Cerebellar examination: Dysdiadochokinesia
- Inability to do RAMs
- Slow, but regular –> cerebral dysfunction
- Fast, but irregular –> cerebellar dysfuntion
Neuro exam: Sensory
- Done in random fashion, on pts w/out specific sensory complaints
- For those w/ sensory complaints, testing is performed in a methodical fashion
- All testing is done w/ pt’s eyes closed
- Pt must be alert & cooperative for reliable results
- Start distally on each extremity & work proximally
- Keep in mind underlying dermatomal patterns
Important landmarks: Upper extremities
- Thumb: C6
- Middle fingers: C7
- 5th digit: C8
Important landmarks: Trunk
- Nipple line: T4
- Umbilicus: T10
Important landmarks: Lower extremities
- Anterior thigh: L3
- Anterior shin: L4
- Top of foot: L5
- Bottom of foot: S1
Sensory exam: Light touch
- Use cotton-tipped applicator to lightly touchskin
- Instruct the pt to acknowledge when they feel the touch
- Start distally, work proximally
Sensory exam: Pain sensation
- Check for sharp vs. dull by alternately using a cotton tipped applicator broken in 1/2
- Start distally, work proximally
Neuro exam: Reflexes
- Involuntary defense mechanisms (involve as few as 2 neurons - 1 sensory afferent, 1 motor efferent)
- Integrity of reflexes dependent upon intact afferent, synaptic, & efferent neurons
Biceps reflex
C5-C6
- Indirectly tap biceps tendon to elicit forearm flexion
Triceps reflex
C7-C8
- Tap triceps tendon to elicit forearm extension
Patellar reflex
L3-L4
- Tap patellar tendon to elicit knee extension
Achilles reflex
S1-S2
- Tap Achilles tendon to elicit plantar flexion
Plantar response (Babinski)
L4-S1
- Stroke lateral aspect of the sole from heel to ball of foot
- Normal response = plantar flexion
- Dorsiflexion of big toes = + response
- Associated w/ CNS (UMN) lesion in corticospinal tract
Clonus
- Involuntary rhythmic oscillations btwn contraction & relaxation (e.g. btwn plantar & dorsiflexion)
- Seen w/ hyperactive reflexes; consistent w/ UMN disease
Brachioradialis
C5-C6
- Tap tendon/radium about 1-2+ inches above wrist to elicit forearm flexion & supination
Involuntary movements
- Tics
- Oral-facial dyskinesias
- Chorea
- Athetosis
- Myoclonus
- Tremors
Tics
- Brief, repetitive twitching, usually of face or upper trunk
- May see winking, grimacing, or shrugging
- Causes: idiopathic, drugs, Tourette’s
Oral-facial dyskinesias
- Rhythmic, repetitive, bizarre movements of face, mouth, jaw, & tongue
- Associated w/ psychotropic meds
Chorea
- Rapid, jerky movements of face, trunk & extremities
- Seen w/ Huntington’s disease
Athetosis
- Writhing, twisting movements of face, trunk & extremities
- Seen w/ cerebral palsy
Myoclonus
Brief, involuntary twitching of a muscle or a group of muscles
Resting tremor
- Most prominent at rest
- Disappears w/ movement
- Seen w/ Parkinson’s
Postural tremor
- Appears when actively maintaining posture (head or extremity)
- Seen w/ benign familial tremor & hypothyroidism
Intention tremor
- Absent at rest; appears when reaching for target
- Seen w/ aging, cerebellar disease & MS
- May be familial
Asterixis (aka. liver flap)
- Abnormal tremor consisting of involuntary jerking movements, esp. in the hands
- Assoc. w/ various encephalopathies
- Can be a sign of hepatic encephalopathy (assoc. w/ cirrhosis)
Disorders of muscle tone
- Spasticity
- Rigidity
- Flaccidity
Spasticity
- Increased tone, worse w/ rapid movement
- Due to UMN disease; loss of tone inhibition
Rigidity
- Increased tone & resistance to movement; independent of rate of movement
- Seen w/ basal ganglia disease
- E.g. “cog-wheel” rigidity in Parkinson’s
Flaccidity
- Decreased tone
- Due to LMN disease (spinal cord or root injury)
Seizure
- Sudden disruption of the brain’s normal electrical activity - Accompanied by altered consciousness &/or other neurological & behavioral manifestations
Status epilepticus
- Life-threatening continuous series of generalized tonic-clonic seizures w/out return to consciousness btwn them
- Tonic (rigid), clonic (uncontrolled jerking)
Epilepsy
Recurrent seizures that may include repetitive muscle jerking (convulsions)
Dementia
- Irreversible state of cognitive impairment & short term memory loss
- Related to organic brain disease, most commonly Alzheimer’s or multiple cerebral infarcts
- At risk for delirium
Delirium
Treatable acute state of cognitive impairment & confusion that may be related to illness, medications, or other causes
Lethargy
Pt is sleepy, but will open eyes & respond before falling back to sleep
Obtundation
- Harder to arouse w/ verbal stimuli – may need to shake him/her
- Responses are slower & tend to be confused; decreased interest in environment
Stupor
- Often cannot be aroused unless painful stimuli is applied
- Voice & shaking ineffective
- Lapse into unresponsiveness when stimuli cease; minimal awareness of self or environment
Coma
Sustained loss of consciousness that does not reverse w/ internal or external stimulation
- Associated w/ significant mortality (90% of people who survive awaken in 1st 3 days)
- Does not respond to verbal or painful stimuli
- Eyes closed & unarousable; no response to environment
Causes of coma
- Cardiac arrest
- Overdose
- Stroke
- Cerebral edema
- Metabolic conditions
- Traumatic brain injury
- Untreated status epilepticus
Glasgow coma scale
Aims to give a reliable, objective way of recording the conscious state of a person
- Eye opening
- Motor response
- Verbal response
- Total score = E+M+V (15 = wide awake, 3 = deep coma)
- Head injury: Score of < or = 8, or coma > 72 hrs = poor prognosis
Other coma assessments
- Posturing
- Pupillary responses
- Brainstem reflexes
- Oculocephalic
- Vestibulocochlear reflex
- Respiratory patterns
Abnormal posturing: Decerebrate rigidity
- Abnormal extensor response
- Jaws are clenched & neck extended
- Extension of elbows & adduction of arms w/ forearms pronated
- Legs extended & feet plantar flexed
- Implies a lesion in the diencephalon or brainstem
- Can occur w/ hypoxia or hypoglycemia
Abnormal posturing: Decorticate rigidity
- Abnormal flexor response
- Flexion of elbows, wrists, fingers & adduction of arms
- Legs extended & internally rotated, feet plantar flexed
- Implies a destructive lesion of the corticospinal tracts near the cerebral hemispheres (brain damage)
Brain herniation
- A deadly consequence of very high ICP
- Brain is squeezed across structures within the skull
- Frequently present w/:
˚ Abnormal posturing
˚ GCS of 3-5
˚ 1 or both pupils dilated & fail to constrict
˚ Tx is urgent –> decompressive craniectomy
˚ Poor prognosis
Oculocephalic reflex (“doll’s eyes”)
- Hold pt’s eyes open & rotate his/her head side to side
- Normal response: eyes move opposite of head
- If eyes remain fixed & move in the same direction of the head movement = brainstem lesion (CN III – CN VIII)
˚ “Doll’s eyes absent”
Vestibulocochlear reflex
- Hold pt’s head at 300; lavage ear w/ ice-cold water
- Normal response: Slow eye deviation toward ear (stimulus)
- No response = brainstem lesion (CN III – CN VI)
Alterations in mood
Mood: Internal emotional tone
- Dysphoric: unhappy, depressed, dissatisfied
- Euphoric: mild elation; exaggerated feelings of wellbeing
- Anxious
- Angry
Alterations in affect
Affect: external range of expression, objective assessment of mood
- Full/normal: appropriate range of emotions
˚ “Affect congruent with mood”
- Blunted or restricted: moderately reduced range of affect
- Flat: absence of all or most affect
- Labile: multiple abrupt changes in affect
Dysarthria
- Problem w/ motor speech or articulation
- Seen w/ bulbar or pseudobulbar palsy
- Bulbar palsy: impairment CNs IX, X, XI & XII, which occurs due to a LMN lesion either at the medulla or from lesions of the lower cranial nerves outside the brainstem
- Pseudobulbar palsy: impairment CNs IX-XII due to UMN lesions of the corticobulbar tracts in the pons
Dysphonia
- Weak or breathy voice
- Vocal cords not well approximated
- Seen w/ presbyphonia, vocal cord nodules, polyps, tumors, or paralysis
Aphasia
Impairment of language ability
- Common w/ strokes, trauma, & mass lesions
Receptive (Wernicke’s) aphasia
Comprehension not intact; fluent, but nonsensical speech
Expressive (Broca’s) aphasia
Comprehension intact; unable to speak to varying degrees
Global aphasia
Combination of receptive & expressive aphasia
Apraxia
Inability to perform a learned motor act despite desire & physical ability to perform
- Disorder of motor planning
- May be seen w/ parietal lobe lesions
Agnosia
- Inability to recognize sensory stimuli
- Any sensory modality can be affected (e.g. olfactory or auditory agnosia)
- Associated w/ large parieto-occipital-posterior temporal lesion (CVA or dementia)
Vibration (128 Hx tuning fork)
- Place on bony prominence; ask what is felt & when it stops
- If distal areas (e.g. fingers & toes) are normal, can assume proximal areas are also normal
- Often the 1st sensation to be lost w/ peripheral neuropathy
Proprioception
- Move thumb up & down; ask pt to identify the direction.
- Repeat w/ great toe
- Technique: hold the sides of the digit
- If distal areas (e.g. fingers & toes) are normal, can assume proximal areas are also normal
- Can occur w/ MS or B12 deficiency due to posterior column disease
- Can also occur w/ peripheral neuropathy
Discriminative sensations
- Test the ability of the sensory cortex to interpret sensations
- These sensations also rely on touch & proprioception (Therefore testing discriminative sensations is only useful when touch & position sense are intact)
- Sterognosis, graphethesia, 2-point discrimination
Testing sensory cortex
- Stereognosis: ask pt to identify common object placed in hand
- Graphesthesia: draw a # (0-9, oriented to the pt) on his/her palm &/or dorsum of his foot & ask him/her to to identify it
- 2 point discrimination: move 2 pins closer together until pt can only appreciate 1 point (Normal - Fingerpads < 5mm, Toes 3-8 mm)
Tactile localization (aka “extinction” or “double simultaneous tactile stimulation”)
- Simultaneously touch the pt on 2 separate sites
on opposite sides of the body & ask what he/she feels - W/ a lesion of the R sensory cortex, the pt may not be able to recognize the stimulus on the L side of the body & vice versa
Kernig’s sign
- Supine - flex hip & knee, & attempt to straighten leg
- Low back pain w/ maneuver = + = meningeal irritation
Brudzinski’s sign
- Supine - place hands behind neck & attempt to flex the neck toward the chest
- Involuntary flexion of hips & knees = + = meningeal irritation
