QuestionSBA
QuestionChoice
This patient is suffering from motor neuron disease which classically presents with both upper (UMN) and lower motor neuron (LMN) signs. In this patient, spastic weakness is a UMN sign and hyporeflexia is an LMN sign. Furthermore, motor neurone disease does not present with sensory signs or symptoms. Diagnosis is typically clinical and needs to be made by a specialist.
10000341
a
Motor neuron disease
QuestionChoice
The diagnosis cannot be mononeuritis multiplex (MNM) for several reasons. Firstly, MNM is a peripheral nerve condition commonly caused by vasculitis and therefore presents only with LMN and sensory signs in the distribution of the affected nerve. This patient has UMN signs and so this is contrary to a diagnosis of MNM. Furthermore, MND does not present with sensory signs as it is characterised by progressive loss of motor, not sensory, neurons. Lastly, MNM commonly presents with neuropathic pain which is not present in this case.
10000343
c
Mononeuritis multiplex
QuestionChoice
This patient has both UMN and LMN signs, which is pathognomonic of motor neuron disease. Multiple sclerosis typically only features UMN signs as it is a demyelinating disease of the central nervous system. Furthermore, MS is most common in females between the ages of 20-40, whereas the average age of MND diagnosis is ~57. Lastly, MS most commonly presents in a relapsing-remitting fashion though the less common subtype of primary progressive MS presents with progressive symptomatology.
10000342
b
Multiple sclerosis
QuestionChoice
Lumbosacral radiculopathy occurs as a result of nerve root compression or inflammation, commonly due to herniation of intervertebral discs. It commonly presents with back pain or radicular pain in the distribution of impinged nerve roots. This is an unlikely diagnosis as no pain is present in this case. Furthermore, because nerve roots are impinged, lumbosacral radiculopathy will only present with LMN signs, whereas both UMN and LMN signs are present in this case.
10000345
e
Lumbosacral Radiculopathy
QuestionChoice
Although an important differential, myasthenia gravis (MG) cannot explain this presentation. MG is an autoimmune condition caused by antibodies against the acetylcholine receptors of the post-synaptic neuromuscular junction. The characteristic presentation of MG is fatigable weakness which is not described here. Furthermore, MG commonly affects the extra-ocular muscles due to their high concentration of ACh receptors, whereas MND classically spares these muscles. The BMJ also state that MG also does not present with specific UMN and LMN signs, which are present here.
10000344
d
Myasthenia gravis
Concept
Chapter
2693
3746
Motor neuron disease
Topic
141
Neurology
12615
A 56-year-old male presents to the clinic with a 6-week history of having difficulty climbing stairs which has gotten progressively worse. Examination reveals bilateral spastic leg weakness. Ankle jerk reflexes and patellar reflexes are absent but all other reflexes are present and normal. There are no identifiable sensory changes.

Which of the following is the most likely diagnosis?
a