BEDSIDE CLINICS 9TH EDITION

Fasciculation 469
4. Peroneal sign - Tapping the peroneal nerve at the neck of fibula will produce plantiflexion
and adduction of the foot with extension of knee (pedal spasm).
5. IECG — Prolonged Q-T interval.]
N.B. : Symptoms of tetany are.
1. Irritability.
2. Muscle cramps (carpopedal spasm).
3. Peripheral (hand and feet) and circumoral paraesthesia.
4. Triad of symptoms are common in children i.e., carpopedal spasm, laryngysmus stridulus
(stridor, respiratory distress, cyanosis), and convulsions.
5. Dysphagia, dyspnoea, dysuria, abdominal colic etc.
Common causes of hypocalcaemia :
1. Malabsorption syndrome.
2. Hypoparathyroidism or pseudohypoparathyroidism.
3. Acute pancreatitis.
4. Chronic renal failure (CRF).
5. Rickets and osteomalacia.
6. Hypoalbuminaemia.
7. Alkalosis due to hyperventilation (often hysterical) or persistent vomiting (pyloric stenosis).
8. Citrated blood in massive transfusion.
9. Drugs—Calcitonin, bisphosphonates.
* Low total calcium is not associated with tetany if ionised fraction is normal. Low ionised calcium
is associated with tetany irrespective of total calcium level. Transient hypocalcaemia (burn, sepsis)
does not develop into tetany.
** Tetany is rare in chronic renal failure because of the presence of metabolic acidosis.
*** Causes of hypercalcaemia are : Primary hyperparathyroidism, malignant tumours, prolonged
immobilisation, ingestion of excess vitamin A or D, milk-alkali syndrome, Paget’s disease, thiazide
diuretic, Addison’s disease, granulomatous disease (e.g., sarcoidosis).
Causes of lock jaw or trismus :
Trismus develops due to sustained involuntary spasm of masseter and temporalis (masticatory
muscles) resulting in inability to open the mouth and mastication, and is found in :
1. Tetanus (spatula test is positive; trismus is by far the most important early symptom)*.
2. Impacted wisdom tooth.
3. Peritonsillar abscess (quinsy), dental abscess, Ludwig’s angina.
4. Acute follicular tonsillitis.
5. Temporo-mandibular osteoarthritis (Costen's syndrome) or rheumatoid arthritis.
6. Sometimes in drug-induced dyskinesia (metoclopramide, phenothiazines).
7. Sometimes in tetany, strychnine poisoning, cyanide toxicity.
8. Parotitis, mumps.
9. Hydrophidae group of snake bite.
10. Rabies.
11. Anaesthesia-induced malignant hyperthermia.
12. Hysterical.
N.B. : Painful trismus—2, 3, 4; painless trismus—tetanus and others.
* Spatula test—In health, touching the posterior pharyngeal wall by spatula produces reflex opening
of mouth. In tetanus, paradoxically mouth closes in such a way that the spatula can not be taken
out easily. Thus, spatula test is positive in tetanus and negative in others.
** In scleroderma and submucosal fibrosis of oral cavity, the patient may find difficulty in opening
the mouth; but this is not true trismus.
*** ‘Facies’ in tetanus—characteristic risus sardonicus (grimace mimicking ‘smile of satan ) due to
contraction of facial muscles, and blepharospasm.