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1 Where's the lesion? Cheat Sheet (DRAFT) by

The clinical method of neurology

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Upper motor lesions (UMNL)

Site of lesion: Cerebral hemisp­heres, cerebe­llum, brainstem, spinal cord (above anterior horn)
Tone: Increased (spact­icity) ± clonus (invol­untary muscle movement)
Muscle weakness:
- All muscle groups of the lower limb - more marked in the flexor muscle
- In the upper limb weakness is more marked in the extensors
Deep tendon reflexes: Increased (but superf­icial reflexes such as abdominal reflexes are usually absent)
Plantar response: Extensor (upping toe)
Fascic­ula­tion: Absent
Wasting: Late - mainly because of disuse
Damage: Leads to charac­ter­istic set of clinical symptoms known as UMN syndrome

Upper motor neuron

UMN syndrome

Acute manife­sta­tions:
1. Spinal shock - hypotonia & loss of all reflexes on contra­-la­teral side
2. Relative sparing of trunk muscles - trunk muscles are bilate­rally innervated by anterior cortic­ospinal tract, thus lesion of one side of the tract has minimal manife­sta­tion; distal muscles, fingers, toes, fine articu­lations & flexors more than extensors are handled by lateral cortic­ospinal tract, thus affected more
Late manife­sta­tions:
1. Babinski sign
2. Spasticity
3. Hypore­flexia or superf­icial reflexes
4. Contra­lateral or ipsila­teral involvement
5. Involv­ement below the lesion
6. Decort­icate posture (person is stiff with bent arms, clenched fists, and legs held out straight)
7. Decere­brate posture (arms and legs being held straight out, the toes being pointed downward, and the head and neck being arched backward)

Lesions

Focal lesion: Diseas­e/p­ath­ology that can develop in one specific area of CNS (e.g. nerve compre­ssion due to sclerosis)
Multifocal lesion: Diseas­e/p­ath­ology that can develop in multiple specific areas of the nervous system (e.g. multiple sclerosis)
Diffuse lesion: Diseas­e/p­ath­ology that has dispersed affect on the nervous system (e.g. polyne­uro­pathy due to diabetes)

Disease course & tempo

Degene­rative condition:
- Slow
- Gradual onset
- Progre­ssively worsening neurol­ogical signs
Vascular condition:
- Abrupt­/sudden onset
- Flactu­ating pattern of neurol­ogical signs
Inflam­matory condition:
- Gradual relaps­ing­-re­mitting pattern of neurol­ogical signs
- (symptoms getting worse followed by recovery, after each relapse it gets worse)
 

Lower motor neuron lesion (LMNL)

Site of lesion: Anterior horn cell, nerve roots, peripheral nerves, neurom­uscular junction, muscles
Tone: Decreased (flacc­idity)
Muscle weakness:
- More distally than proximally
- Both flexors & extensors affected
Deep tendon reflexes: Reduced or absent
Plantar response: Normal or absent
Fascic­ula­tion: May be present in anterior horn cell lesions
Wasting: Usually present
Damage: Usually causes hypore­flexia, flaccid paralysis, & atrophy

Lower motor neuron

Neurom­uscular junction lesion

 

Muscular lesion

 

Applied example 1

Case: 72-yea­r-old male presents with a right side face and arm weakness - came on over a few months
Pathol­ogical process: Tumour

Applied example 2

Case: patient presents with a change in cognition, speech, memory, behavi­our­/pe­rso­nality, & mood
Pathol­ogical process: UMNL, frontal lobe (effer­ent­/motor)

Applied example 3

Case: patient presents with changes in CN III - XII function
Pathol­ogical process: UMNL, brainstem / spinal lesion

Applied example 4

Case: patient presents with focal tingling between 4th and 5th finger (no motor abnorm­ali­ties)
Pathol­ogical process: LMNL, peripheral lesion (ulnar nerve)