A 45-year-old woman
presented with a two-day history of diarrhea, vomiting, progressive numbness
around her mouth and generalized body cramps. She had undergone a total
thyroidectomy for a multinodular goiter seven months back. Her vital signs were
stable. Trousseau sign was evidenced a few seconds after the sphygmomanometer
cuff was inflated to more than the systolic blood pressure on the left upper
arm. What is the most likely diagnosis?
Diagnosis
is at the end of the article but first let's answer these questions
what is Trousseau sign?
what is Trousseau sign?
and
what is Chvostek sign?
Signs of
Hypocalcemia
The Chvostek Sign is
a clinical sign of existing nerve hyperexcitability (tetany) seen in
hypocalcemia. It refers to an abnormal reaction to the stimulation of the
facial nerve. When the facial nerve is tapped in front of tragus the facial
muscles on the same side of the face will contract momentarily (typically a
twitch of the nose or lips) because of hypocalcemia with resultant
hyperexcitability of nerves.
Though classically
described in hypocalcemia, this sign may also be encountered in respiratory
alkalosis, such as that seen in hyperventilation, which causes decreased serum
Ca2+ with a normal calcium level due to a shift of Ca2+ from the blood to
albumin which has become more negative in the alkalotic state.
The Chvostek sign in
hypocalcemia can be seen in cases of
hypoparathyroidism,
pseudohypoparathyroidism,
hypovitaminosis
D.
The Chvostek sign
may also be present in hypomagnesemia. Magnesium is a cofactor for Adenylate
cyclase. The reaction that Adenylate cyclase catalyzes is the conversion of ATP
to 3',5'-cyclic AMP. The 3',5'-cyclic AMP (cAMP) is required for parathyroid hormone
activation. It is frequently seen in alcoholics, persons with diarrhea,
patients taking aminoglycosides or diuretics, because hypomagnesemia can cause
hypocalcemia. It is also seen in measles, tetanus and myxedema.
video embeeded from NEJMvideo youtube channel.
Trousseau Sign of latent tetany is a medical sign observed in patients with low calcium. This sign may be positive before other manifestations of hypocalcemia such as hyperreflexia and tetany, as such it is generally believed to be more sensitive than the Chvostek sign for hypocalcemia.
To elicit the sign,
a blood pressure cuff is placed around the arm and inflated to a pressure
greater than the systolic blood pressure and held in place for 3 minutes. This
will occlude the brachial artery. In the absence of blood flow, the patient's
hypocalcemia and subsequent neuromuscular irritability will induce spasm of the
muscles of the hand and forearm. The wrist and metacarpophalangeal joints flex,
the DIP and PIP joints extend, and the fingers adduct. The sign is also known
as main d'accoucheur (French for "hand of the obstetrician") because
it supposedly resembles the position of an obstetrician's hand in delivering a
baby.
The most likely
diagnosis in above case is iatrogenic
hypoparathyroidism.
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