Upgoing Plantar Reflex with Absent Ankle Jerks - Differentials !

Question 1

Upgoing Plantar Reflexes with Absent Ankle Jerks = MRCP favourite

Answer 1

Upgoing plantar with absent ankle jerks = classic five MRCP favourite of:

• Motor neurone disease
• Tabes dorsalis (Neurosyphilis)
• Subacute combined degeneration of the cord
• Friedrichs ataxia
• Syringomyelia
• Dual pathology of central and peripheral causes.

Question 2

Upgoing plantar with absent ankle jerk - Example Question

Answer 2

A 45 year old male is brought into A&E by his partner. He is known to be HIV +ve and his partner reports good compliance with his medications since his diagnosis 4 years ago. A collateral history reveals persistent confusion over the past 3 weeks. His past medical history includes outpatient treatment 2 years ago for lymphogranuloma venereum and type 2 diabetes mellitus. On examination, the patient is not orientated in time or place. He scores 0/10 on the abbreviated mental test. Both heart sounds are present, include a mild early diastolic murmur. Neurological examination is difficult due to poor patient compliance but you note absent reflexes in both lower limbs, with an upgoing plantar on the left and withdrawn plantar on the right. You also note that he has erythematous soles on both feet. Blood tests and blood glucose are awaited. What is the most likely diagnosis?

Subacute combined degeneration of the cord
Motor neurone disease
> Neurosyphillis
Hypoglycaemia and diabetic peripheral neuropathy
HIV dementia and peripheral neuropathy

A number of features suggests neurosyphillis from the history. Firstly, the likely aortic regurgitation on cardiovascular examination should make you suspicious of aortitis, of which syphilitic infection is a classic cause. He has had a range of sexually transmitted diseases. A painless red rash is also a classic sign of syphilis, particularly in palms of the hands or the soles of the feet. He also has a combined upgoing plantar with absent ankle jerks, which narrows the diagnosis to the classic five MRCP favourite of motor neurone disease, tabes dorsalis, subacute combined degeneration of the cord, Friedriechs ataxia and dual pathology of central and peripheral causes. There is little to suggest a genetic disorder presenting in his mid-40s or a vitamin B deficiency to account for SCDC. Neurosyphillis would be the most likely diagnosis.

Question 3

Upgoing Plantars with Absent Ankle Jerks - Full list of Causes

Answer 3

• SCDC
• MND
• Friedrich’s Ataxia
• Syringomyelia
• Tabes Dorsalis (Syphilis)
• Conus Medullaris lesion

CAUSED BY LESION PRODUCING BOTH UMN AND LMN SIGNS