UPPER MOTOR NEURON Vs. LOWER MOTOR NEURON PARALYSIS
| A | Spasticity | |
| B |
Flaccid paralysis |
|
| C |
Hyperactive stretch reflex |
|
| D |
Muscular incordination |
With which one of the following examination finding is associated with lower motor neuron lesions ?
| A |
Spasticity |
|
| B |
Flaccid paralysis |
|
| C |
Hyperactive stretch reflex |
|
| D |
Muscular incordination |
Cortcospinal tract lesion leads to:
| A |
Spaticity |
|
| B |
Extensor plantar response |
|
| C |
Exaggerated tendon reflexes |
|
| D |
All |
A, B, C i.e. Spaticity, Extensor plantar response, Exaggerated tendon reflexes
which of the following is associated with Lower motor neuron lesions?
| A |
Flaccid paralysis |
|
| B |
Hyperactive stretch reflex |
|
| C |
Spasticity |
|
| D |
Muscular incoordination |
Answer is A (Flaccid paralysis):
Lower motor neuron lesions are characteristically associated with weakness of muscles (paralysis) with decreased tone (flaccidity) i.e. flaccid paralysis.
Involvement of pyramidal tract leads to all of the following except
| A |
Spasticity |
|
| B |
Fasciculation |
|
| C |
Hyper-reflexia |
|
| D |
Positive Babinski sign |
Answer is B (Fasciculation):
Fasciculations are a feature of Lower Motor Neuron Lesions.
Involvement of Pyramidal tract indicates an Upper Motor Neuron Lesion. Hypertonia with Spasticity, Hyper-reflexia and a Positive Babinski Sign with an Extensor Planter response are all features of an upper motor neuron lesion (Pyramidal Tract Lesion).
March 2013
| A |
Weakness and Spasticity |
|
| B |
Fasciculations |
|
| C |
Rigidity |
|
| D |
Localized muscle atrophy |
Ans. A i.e. Weakness and spasticity
Which of the following is not a sign of upper motor neuron paralysis
| A |
Babinski sign |
|
| B |
Spastic paralysis |
|
| C |
Denervation potential in EMG |
|
| D |
Exaggeration of tendon reflexes |
Ans. is ‘c’ i.e., Denervation potential in EMG
Difference between upper and lower motor neuron paralysis
|
Upper motor neuron paralysis |
Lower motor neuron paralysis |
| Muscles affected in groups never individual muscles | Individual muscles may be affected |
|
o Atrophy slight and due to disuse |
Atrophy pronounced up to 70% of the total bulk |
| Spasticity with hyperactivity of the tendon reflexes and | Flaccidity and hypotoniaQ of affected muscles with loss of tendon reflexes |
|
Extensor plantar reflex (Babinski sign) |
Plantar reflex if present is of normal flexor type |
| Fascicular twitches absent | Fasciculation may be present |
| Normal nerve conduction studies; no denervation potentials in E.M.G. | Abnormal nerve conduction studies; denervation potential (fibrillations, fasciculations positive sharp waves) in EMG |
| A |
Spasticity |
|
| B | Fasciculation | |
| C |
Hyper-reflexia |
|
| D |
Positive babinski sign |
Ans. is ‘b’ i.e., Fasciculation
- Fasciculation is seen in LMN lesion (pyramidal tract is UMN).
| A |
Flaccid paralysis. |
|
| B |
Muscular hypertrophy. |
|
| C |
Hypo-reflexia. |
|
| D |
Superficial reflex present. |
Ans:B.)Muscular Hypertrophy.
The neuron shown in the picture above represents lower motor neurons.
Muscular hypertrophy is not seen in lesion of lower motor neurons.
Differences between Upper motor neuron and Lower motor neuron Lesions
| Sign | Upper motor neurone | Lower motor neurone |
| 1) Weakness | Voluntary movements are disturbed | Paralysis of muscles supplied by that segment or nerve |
| 2) Tone | Hypertonia (clasp- knife spasticity | Hypotonia |
| 3) Reflex ( tendon) | Increased,+- clonus | Decreased or absent |
| 4) Reflex ( superficial) | Absent or decreased | Absent or decreased |
| 5) Plantar response | Extensor | Flexor or absent |
| 6) Muscle nutrition | Disuse atrophy | Marked atrophy |
| 7) Fasciculations | Absent | Present |
| 8) Reaction of degeneration | Absent | Present |
All of the following signs a can be seen in corticospinal tract injury except:
| A | Positive Babinski sign | |
| B |
Difficulty in performing skilled movements of the distal upper limb |
|
| C |
Superficial abdominal reflex absent |
|
| D |
Clasp knife spasticity |
Ans. d. Clasp-knife spasticity
- When the muscles are hypertonic, as in a UMN lesion, the sequence of moderate stretch —n muscle contraction, strong stretch —n muscle relaxation is seen.
- Passive flexion of the elbow meets immediate resistance as a result of the stretch reflex in the triceps muscle.
- Further stretch activates the inverse stretch reflex. The resistance to flexion suddenly collapses, and the arm flexes.
- Continued passive flexion stretches the muscle again, and the sequence is repeated.
- This sequence of resistance followed by a ‘give’ when a limb is moved passively is known as the clasp-knife effect because of its resemblance to the closing of a pocket knife.
It is also known as lengthening reaction because it is the response of a spastic muscle to lengthening
| Upper Motor Neuron Lesions | Lower Neuron Lesions | |
| Power | Decreased°Weakness (Muscle groups or Limbs being af-fected and not individual musclesQ) | Very much decreasedWeakness (severe) due to paralysis of individual musclesQ |
| Tone | Hypertonia (Clasp knife spasticityQ) | Flaccidity (Hypotonia°) |
| Wasting/Atrophy | Minimal°, if present and due to disuse atrophy | Marked (cardinal feature’) |
| Reflexes | ||
| Superficial reflexes | LostQ | Lost!Q |
| Deep reflexes | Brisk/ExaggeratedQ | ExaggeratedQ |
| Clonus | May be + ntQ | AbsentQ |
| Plantar | ExtensorQ | Flexor or no responseQ |
| Fasciculations | AbsentQ | PresentQ |
| Reaction of degenera tion in muscles | AbsentQ | PresentQ |
