Wk 2 Peripheral Nerve Lecture Flashcards
What is the inheritance pattern of SMA?
Autosomal recessive -> loss of SMN protein
Neurological ROS
- Headache
- Dizziness
- Difficulty with coordination
- Tremors
- Weakness
- Numbness
- Problems with balance
Paresis
impaired strength or weakness
Paralysis or plegia
absent strength
(hemiplegia, paraplegia, tetraplegia)
Paralysis or plegia
absent strength
(hemiplegia, paraplegia, tetraplegia)
Radiculopathy
dysfunction of a spinal nerve root (often due to compression)
Neuropathy
dysfunction of a nerve
Allodynia
pain due to a stimulus that normally does not provoke pain.
Light touch/feather could provoke pain
What 4 things do we examine during a motor exam?
- Inspection: normal muscle bulk vs atrophy (reduced bulk) or hypertrophy (increased bulk)
- Tone:
- Pronator drift: a sensitive screen for mild weakness
- Muscle strength
– Isolate individual movements
– Know spinal root innervation of muscles tested (myotomes) * + Radial/Ulnar/Median nerve exams
Pronator drift test
(+) = abnormal, see drift
(-) = absent, no drift
-testing upper motor neuron: strength and motor control
-pronation is more primitive
Motor exam strength grading (MRC)
- 5 : Normal: movement against full resistance
- 4 : movement against gravity and some resistance
- 3 : movement against gravity alone
- 2 : movement across joint with gravity removed
- 1 : Visible muscle contraction, no movement at the joint
- 0 : No muscular contraction at all
nerve level motor exam arm testing
C5: Shoulder abduction
C6: Elbow flexion/Wrist Extension
C7: Elbow extension/Wrist flexion
C8: Thumb extension
T1: Finger Abduction & Adduction
- T1/Ulnar nerve – Finger abduction
- T1/Median nerve – Thumb opposition
Motor testing in the legs
- L1,L2 –hip flexion (iliopsoas)
- L2,L3 –thigh adduction (adductors)
- L3,L4 –knee extension (quadriceps)
- L4,L5 – ankle dorsiflexion (tibialis anterior)
- S1 – knee flexion (hamstrings)
- S1,S2–ankleplantarflexion(gastrocnemius/soleus)
What 4 components are tested in the sensory exam?
- proprioception
- vibration
- light touch
- pain and temp
Meaningful patterns in sensory exam
What is the Romberg sign?
Tests proprioception
* Patient stands with feet together
with eyes open
* Have patient close eyes x 10
seconds
– ‘absent’ = normal
* Patient does not lose balance when eyes closed (micro-adjustments okay)
– ‘present” = abnormal:
* Patient loses balance; takes a step or has to open their eyes
What are 5 causes of distal sensory polyneuropathy?
- Metabolic: – Type 2 DM and prediabetes > type 1 DM,
hyperlipidemia, B12 deficiency - Idiopathic:
– 40% of those presenting with distal sensory polyneuropathy. Often, found to have metabolic syndrome. - Toxic:
– Alcohol, chemotherapy, lead, mercury,
arsenic and thallium, vitamin B6 toxicity - Infectious:
– Lyme, herpes, hepatitis, HIV and syphilis - Immune:
– Sarcoid, Sjogren’s, Guillain-Barre syndrome, vasculitis, amyloidosis/MGUS (monoclonal gammopathy of uncertain significance)
What is the significance of an abnormal vibration exam?
abnorm = never felt vibration or lose sensation earlier than tester does
Dorsal column dysfunction
What is the scale for reflex grading?
- Descriptive: “absent” “present” “brisk” * Scale:
– 0 absent
– 1+ trace, or only seen with reinforcement
– 2+ normal
– 3+
– 4+ very brisk (jumpy) associated clonus
*Note: 1+ and 3+ are normal in many situations
BUT asymmetric reflexes, and 4+ is always abnormal.
“0” is presumably abnormal but may be due to ‘technical’ difficulties or age
What’s included in the reflex exam?
- C5 - biceps brachii reflex
- C6 - brachioradialis reflex
- C7 - triceps reflex
- L4 - patellar reflex
- S1 - Achilles reflex
- Babinski
What is the Babinski sign?
Plantar reflex
* Normal Response: Down going toes
– Say: “Absent Babinski”, “flexor plantar response”
or “down-going toes” NOT “negative Babinski”
- Abnormal Response: Upgoing toes +/-
fanning of the toes
– Say: “Babinski sign present,” “Extensor plantar
response” or “up-going toes” - Babinski sign: disinhibition of spinal cord circuits due to loss of corticospinal track modulation (upper motor neuron sign)
- When is this normal to have?… – Neonates/infants
When would we see hyperreflexia?
Dysfxn/damage to descending corticospinal tract
-caused by damage to CNS by many pathologies
What causes hyporeflexia?
Interruption of efferent or afferent arcs due to:
– Peripheral neuropathy
* Guillain Barre syndrome (AIDP); other peripheral neuropathies
– Myopathy- muscular dystrophy or inflammatory myopathy
– Hypothyroidism
– Electrolyte imbalance (elevated magnesium or calcium)
– Anterior horn cell disease
* Spinal muscular atrophy; others – Botulism, Polio
What are fasciculations?
muscle twitches
=lower motor neuron sign
Signs of ALS?
Lower and upper motor neuron signs (one of the few pathologies w/ both)
-weakness, muscle atrophy
-lower fasciculations
-upper spasticity
How to document a norm peripheral nerve exam
