Funtabulously Frivolous Friday Five 062

• Corrigan’s sign
• This is one of the many eponymous signs of aortic regurgitation, and refers to the presence of prominent carotid pulsations. In fact, aortic regurgitation was once known as Corrigan’s disease.
• Corrigan’s sign is shown in the video below:

• Sir Dominic Corrigan (1802-1880) was a hard-working, famous Dublin physician who is said to have had a secret door created in his consulting room so that he could escape the throngs of patients awaiting his curative touch. He is credited with the following quotation:

“The trouble with doctors is not that they don’t know enough, but that they don’t see enough.”

• Rabies
• Rabies is one of the most lethal infections afflicting humankind.
• After a 9-90 day incubation period (can be longer) the rabies rhabdovirus makes it way from the infected bite site (typically inflicted by a dog, bat, cat, fox or raccoon) to the patient’s central nervous system. Among the characteristic features of ‘furious rabies’ is the bizarre and distressing manifestation of hydrophobia.
• Examples are shown in the videos below (they make distressing viewing) — get vaccinated if you’re in a rabies area.

• There have been rare cases of survival from rabies. The most celebrated case is that of 15 year-old Jeanna Giese, who was treated with the Milwaukee Protocol, as featured in the documentary ‘Extraordinary people — The girl who survived rabies’:

Willoughby RE Jr, Tieves KS, Hoffman GM, Ghanayem NS, Amlie-Lefond CM, Schwabe MJ, Chusid MJ, Rupprecht CE. Survival after treatment of rabies with induction of coma. N Engl J Med. 2005 Jun 16;352(24):2508-14. PMID: 15958806. [Free fulltext]

• Myotonic dystrophy.
• Features of myotonic dystrophy include grip myotonia and percussion myotonia, shown in the video below. Muscular contraction is sutained, and relaxation is slow.

• Always check the ankle jerk reflex (S12 level via the tibial nerve)  in a patient with a foot drop because:

• if it is normal, then a common peroneal nerve lesion (L45S1) is likely.
  This is usually due to an injury at the neck of the fibula where the common peroneal nerve divides into its superficial and deep branches.
  If foot eversion is spared then the superficial peroneal nerve (L5S1)  is intact (innervates peroneus longus and brevis).
  An L5 root lesion can also cause foot drop and an intact ankle jerk, but there should also be weakness of knee flexion and foot inversion, as well as an L5 sensory deficit.
• if it is absent, then a lower motor neuron lesion affecting the sciatic nerve or lumbosacral plexus is likely.
  Such a lesion must involve nerve fibers that mediate the ankle jerk from the S12 level via the tibial nerve (a branch of the sciatic nerve), as well as nerve fibers that mediate ankle dorsiflexion from the L45 level via the deep peroneal nerve to tibialis anterior, extensor hallucis longus, extensor digitorum longus and extensor digitorum brevis.
• if it is hyperreflexic, an upper motor neuron lesion is present (e.g. stroke).

Sciatic nerve giving rise to the tibial and common peroneal nerves

• Causes of foot drop include:

• common peroneal nerve palsy
• sciatic nerve palsy
• lumbosacral plexus lesion
• L45 root lesion
• peripheral motor neuropathy
• distal myopathy
• motor neuron disease
• stroke (anterior cerebral artery or lacunar syndrome causing ‘ataxic hemiparesis’)

Easy, eh.

• The majority of screws have right-handed thread, meaning that they are tightened by clockwise rotation.
• Using one’s right-hand enables the powerful biceps brachii muscle to supinate the forearm to achieve clockwise rotation of the screw. This action is most effective when the elbow is flexed.
• Using the left-hand to turn a screw with right-handed thread requires pronation of the forearm. This is a weaker action than supination as biceps brachii does not assist in pronation.
• An exception is the screw on your left-sided bicycle pedal. Such screws are subject to anti-clockwise torque and are more likely to stay tight if they have a left-handed thread.
• Note the increased contraction of biceps brachii when the forearm is supinated (top) compared to when the forearm is pronated (bottom):

Biceps fully contracted during elbow flexion and forearm supination (Click image for source)

Biceps partially contracted during elbow flexion and forearm pronation (Click image for source)