M3 Clinical Neurology Flashcards
The bulk of research published within upper cervical chiropractic can generally be found under the following 3 categories;
- Autonomic Nervous System
- cerebellum/basal ganglia / frontal lobe connection
- Cranial Nerves
The ANS regulates the three main homeostatic systems in the body. What are they and what chemical messengers does each use?
- Immune System - cytokines
- Endocrine System - hormones
- Nervous System - neurotransmitters
Divisions of ANS
- Sympathetic
- Parasympathetic
- Enteric
Sympathetic Nervous system
Connected to stress response. Drives movement in any form.
Parasympathetic Nervous System
Relates to healing and digestion
Enteric Nervous system
a mesh-like system of neurons that governs the fn of the gastrointestinal tract. Referred to as 2nd brain.
Polyvagal Theory
- Developed by Steven Porges in 1991.
2. Proposes two different vagal systems: DVC and VVC
Dorsal Vagal Complex
Unmyelinated Innervates viscera below diaphragm Origin: Dorsal Medial Nucleus in Medulla "Freeze" response Matures 4th month in utero
Sympathetic Nervous System
Movement system
Begins development 16th week in utero
Matures in 3rd trimester
Brakes “Freeze”
Ventral Vagal Complex
Myelinated Innervates viscera above the diaphragm Origin: Nucleus Ambiguous in ventral medulla Begins development in 3rd trimester Matures at 6th - 12th month Modulates SNS Responsible for Social Engagement System
Rostral Ventral Lateral Medulla
- Sandwiched between DMN and NA
2. Provides governances for SNS
Difference between SNS and PaNS responses.
SNS has global response
PaNS has local response
Heart Rate Variability
Assesses the function of the VVC.
Respiration is the biggest factor:
1. Inhalation increases SNS, increasing heart rate.
2. Exhalation increases PaNS, decreasing heart rate.
We lose our ability to vary heart rate when there is compromise of the VVC, thus an autonomic imbalance.
Circulation and the SNS
- Blood pressure and pulse rate are governed primarily by the SNS.
- Circulating Norepinephrine will raise or lower pending ANS balance. NE levels rise with sympathetic activation resulting in constriction of the vessels. This drives blood pressure up.
- SNS 100% affects the SA Node, regulating pulse rate. The VVC causes it to slow down.
episodes of slow pulse rate, low blood pressure, low blood sugar, passing out, vasovagal responses, etc indicate what?
Decreased sympathetic tone, increasing effect of DVC. Can come from poorly developed or exhausted SNS consistent with adrenal fatigue.
Gut and immunity
- 60-80% of immune system is in gut.
- Inflammation in gut can be transmitted to the brain via the vagus nerve.
- The gut, as the second brain, is the home of the
enteric nervous system and can independently drive autonomic function
Typical history of:
Underactive PaNS
- Dry mouth
- Difficulty swallowing supplements or large bites of food
- Slow bowel movements/tendency for constipation
- Chronic digestive complaints
- Bowel or bladder incontinence
Typical history of:
Overactive SNS
- Tendency for anxiety
- Easily startled
- Difficulty relaxing
- Sensitive to bright or flashing lights
- Episodes of racing heart
- Difficulty sleeping
Typical history of:
Weakened SNS response
- Passing out
- Low blood pressure
- Low blood sugar
- Low pulse rate
- Fatigue
- Low libido
- Weight gain
- Frequent colds/sinusitis
Observation - Pupils
- The oculomotor nerve (CN III) is a parasympathetic nerve and controls pupil constriction.
- Large symmetrical pupils = overactive SNS, normal is infants.
- Asymmetrically large pupils are increased on side of weekend hemisphere
- Small pupils can indicate a parasympathetic response. (or atrophied ciliary muscles in elderly).
Pupillary Light Reflex
- The pupil should constrict for 4 to 5 seconds, then gradually lose the constriction and yield. (CN III)
- Losing constriction within a couple of seconds or oscillation is positive for a weakened PaNS
ANS and facial symmetry
Look for:
- deeper nasolabial fold
- eye opened wider on one side
- drooping lip
ANS balance and temperature
Middle finger and wrist should be within 2 degrees F. If finger is cooler then overactive dominance.
ANS balance and fingernails
White spots can be banged fingers with decreased blood supply so less healing, therefore SNS dominance.
ANS balance and capillary refill time
If it takes longer than 2 seconds for color to return to the patient’s finger, it is considered a slow capillary refill time. This is attributed to decreased circulation and can be an indication of an overactive SNS
ANS balance and orthostatic hypotension
BP should increase 10mmHG when standing from laying or sitting. As we stand up, brain stem communicates with the adrenal medulla and the adrenal medulla releases epinephrine and norepinephrine into the system. This causes an immediate increase in blood pressure for the purpose of pushing blood into the cranial vault against gravity. This is a SNS activity. As this system wanes or
weakens orthostatic hypotension can be the result.
ANS balance and Pulse Pressure
- difference between the systolic pressure and the diastolic pressure. The normal for pulse pressure is 40.
- Pulse pressure is an interplay between stroke volume and circulatory resistance.
- the most common reason for stiffening of these arteries (elevated pulse pressure) is an overactive SNS activating muscle contraction within these arteries
Testing CN III, IV and VI
Pupillary Light Reflex Extraocular Movements 1. Look for ptosis, eye position, and nystagmus 2. "H" Pattern 3. Nystagmus testing 4. Accommodation
Testing CN V
- Test light touch, pain and temperature at forehead, cheeks and chin (pinpoint, not stroking)
- Corneal reflex (blinking is CN VII)
- mastication muscles
- Jaw jerk reflex
Testing CN VII
- Facial symmetry
- Muscles of facial expression
- Taste
Testing CN IX
- Gag response
- Uvular deviation (away from affected side)
- Palatal articulation “Kah”
- Glottal articulation “Go”
Testing CN XI
- Shrugging shoulders
2. Turning head from side to side
Testing CN XII
Stick out tongue and move it to one side, then the other
Inspect for tongue atrophy, fasciculations or asymmetry in movement or
appearance
Suggested order of brief CN Nerve exam
- XII: Stick out tongue.
- X/IX: Say “Ah” then gag reflex
- VII: raise eyebrows, then puff cheeks, then smile
- V: cotton ball for corneal reflex, then forehead, cheeks and chin.
- III: observe eyes for PERRLA, convergence,
smooth pursuits, pupillary reflex - XI: shoulder shrug and head rotation
CNs related to VVC
5, 7, 9-12 (3 not related to VVC but important PaNS response).
Which brain hemisphere develops more in first three years of life?
Right hemisphere - social engagement side, has mirror neurons to mimic things around and to help intuit others emotions (empathy).
Movement intitiation and refinement loops
- Motion initiation starts in frontal cortex.
- Messages sent simultaneously to:
a. Basal Ganglia to speed up movement (with thalamus).
b. Cerebellum: refines movement continuously (8-10 cycles). - Loops connected to the ANS and limbic system.
3 lobes of cerebellum
Anterior
Posterior
Flocculonodular
Cerebellar Anterior Lobe
- a significant portion of the midline cerebellum
- houses the fastigual and interpose nuclei
- responsible for mediating unconscious proprioception
- Inputs are mainly from the spinal cord.
Cerebellar Posterior Lobe
- houses the dentate nucleus
- an important role in fine motor coordination.
- receives input mainly from the brainstem (i.e., reticular formation and inferior olivary nucleus) and
cerebral cortex - This lobe is the lateral most lobe.
Cerebellar Flocculonodular lobe
- houses the vestibular nucleus
- uses information about head movement to influence eye movement and balance.
- on the anteroinferior surface of cerebellum and
connected to the midline structure by thin pedicles - receives inputs from the labyrinthine system. The flocculonodulus is the vestibulocerebellum
4 cerebellar regions
- flocculonodulus
- vermis
- paravermis
- hemispheres or lateral cerebellum
Cerebellar Vermis
- most midline structure and houses the fastigual nucleus
a. Related to the vestibular system
b. interprets body motion and places it on spatial planes to estimate the movement of the body through space.
c. large influence on postural muscles, esp spine - Saccadic eye movements
Cerebellar Paravermis
- Just lateral to vermis
- Houses the interpose nuclei:
a. globus: shoulders and hips
b. emboliform: elbows to wrists, knees to ankles
Cerebellar Hemispheres
- Most lateral
- Houses dentate nucleus, largest in cerebellum
- Related to distal joints: hands and feet
- Communicates with cerebrum
3 functional devisions of cerebellum
- Vestibulocerebellum (flocculonodulus)
- Spinocerebellum (vermis and paravermis)
- Cerebrocerebellum (lateral hemispheres)
Vestibulocerebellum anatomy
Flocculonodular lobe and its connection to the
vestibular and fastigual nucleus. It receives input from the labyrinthine system and the central structures. Since the flocculonodular lobe deals with axial controls and vestibular reflexes, a pathology of this system could give the following disturbances:
• Equilibrium
• Gait ataxia
Vestibulocerebellum lesions
considered midline and the following are possible findings: A. VOR response B. Titubation C. Ataxia of stance D. Ataxic gait E. Head tilt F. Dysarthria G. Saccadic pursuits H. Dysmetria of saccades
Spinocerebellar Anatomy
Vermal and paravermal regions and their relationship
with the interposed and fastigual nuclei. Receives somatosensory inputs exclusively from the spinal cord. It receives information about the length and tension of muscle fibers (i.e., unconscious proprioceptive sensation).
Spinocerebellar Lesions
A. Gait instability B. Ataxia in the trunk C. Titubation and breakdown of movements D. Saccadic dysmetria E. Vertiginous activity possibly exocentric or egocentric, depending on the state of the cortex
Cerebrocerebellar Anatomy
The lateral hemisphere of the cerebellum receives
information exclusively from the cerebral cortex. It is part of the posterior lobe. Without the cerebrocerebellum the frontal lobe would not expand so
greatly and there would not be the level of lateralization that takes in development. Lateralization is what gives distinction between functions of both hemispheres. It makes the right brain have specific characteristics as well as the left. The distinctions are necessary for higher developed functions seen in human as well as complex cognition.
Cerebellar Peduncles
- Superior Cerebellar Peduncle (midbrain)
- MIddle Cerebellar Peduncle (pons)
- Inferior Cerebellar Peduncle (medulla)
Superior Cerebellar Peduncle
- Majority is the interposed and dentate nuclei outputs that go up to the cerebrum
- Ventral Spinocerebellar tract comes in here
- Locus ceruleus noradrenergic fibers enter through here
Middle Cerebellar Peduncle
Almost exclusively pontocerebellar fibers
Inferior Cerebellar Peduncle
- Olivocerebellar fibers from the contralateral medulla
- Dorsal spinocerebellar and cuneocerebellar
- Vestibular afferents, arcuate NU, Trigeminal, raphae serotonergic, reticular afferents and fastigual outputs
The Purkinje System
- A breaking system for the cerebellum. Without a braking system for the cerebellum there is too much activation for all the areas influenced by each specific nucleus.
- Related to mossy and climbing fibers.
- Sensitive to oxygenation and other environmental factors.
Sporadic ataxia
Ataxia not coming from a known neurological problem.
Mossy fibers
Input to cerebellum, primarily activate deep nuclei.
Climbing fibers
Activate Purkinje cells, causing deep nuclei inhibition.
Observation of Cerebellar Dysfunction
- Handwriting - macrografia
- Head tilt - away from weak side (and left head tilt may cause writing to slope upwards and right head tilt may cause writing to slope downwards.
- Essential tremor
Essential tremor
- A neurological disorder that causes involuntary and rhythmic shaking. Can be from Cerebellar dysfunction.
- Essential tremor most often affects the hands, though it may also affect the head, voice, arms, or legs. It’s not related to Parkinson’s disease.
- Shaking occurs with simple tasks such as tying shoelaces, writing, or shaving. Symptoms may be aggravated by stress, fatigue, caffeine, and temperature extremes.
spinocerebellar dysfunction history
• Difficulty with balance, or balance that is worse on one side
• A need to hold the handrail or watch each step carefully when going down
stairs
• Feeling unsteady and prone to falling in the dark
• Prone to sway to one side when walking or standing