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Author:
Balaji Vishwanat, MD
Physician Emeritus,
Department of Neurology
Gundersen Lutheran Health System
La Crosse, Wisconsin
Address for correspondence:
David Hartman, PhD,
BC-ANCDS(A)
Mail Stop EB3-002
Gundersen Lutheran Health System
1900 South Avenue
La Crosse, WI 54601
Telephone: (608) 775-9000
Fax: (608) 775-6358
email: dehartma@gundluth.org
The Tensilon Test: A Case Report
Abstract
A patient presented with symptoms and signs consistent with a diagnosis of myasthenia
gravis (MG), a neuromuscular junction disorder. Herein, findings from the patient’s physical
examination and results of the edrophonium chloride (Tensilon) test administered to confirm
the MG diagnosis are reported. The symptoms and underlying pathophysiology of MG are
described. Finally the array of tests that can be used to aid in a diagnosis of MG are reviewed.
A
68-year-old man presented with a 2-month history of
weakness of his jaw, drooping of his left upper eyelid, and
double vision. All his symptoms were intermittent in nature. His
jaw tired after he had chewed 3 or 4 mouthfuls and would recover
after resting for a couple of minutes. The left upper eyelid would
be fine in the morning but would start drooping by noon and stay
that way the rest of the day. The double vision was also prominent
toward the end of the day. He had experienced no difficulty
swallowing or breathing. He had experienced no weakness of his
neck muscles. His extremities were perfectly strong. Medical history
was significant for rheumatic fever in childhood leading to aortic
stenosis. He required aortic valve replacement and 2 revisions.
Complete review of systems was unremarkable. The patient was
taking no prescription medications.
Findings from a general physical examination were
unremarkable. A very definite ptosis was present on the left. The
patient had binocular diplopia on right and left lateral gaze. Jaw
muscles were normal but easily fatigued. Mild bilateral lower motor
neuron facial weakness was evident. Limb musculature strength
was normal. Deep tendon reflexes were normal and the plantar
responses flexor. There were no sensory deficits.
An edrophonium chloride (Tensilon) test was performed
(Figures 1 and 2).
(1) What is the likely diagnosis?
(2) What does the Tensilon test show?
(3) How would you manage this patient?
junction by antibodies to the postsynaptic acetylcholine receptors
(AChR). Normal quanta of acetylcholine are released at the
nerve terminal, but the response is reduced, leading to weakness.
In contrast, the defect in Lambert-Eaton syndrome lies in the
presynaptic nerve terminals due to antibodies directed toward
calcium channels and the release of insufficient quanta of
acetylcholine. 1 Cobra venom and bungarotoxin produce blockage
of neuromuscular transmission by prolonged nondepolarization of
the neuromuscular junction. Botulinum toxin causes blockage of
acetylcholine release from nerve terminals.
In MG, the extraocular, facial, jaw, bulbar, neck, and shoulder
girdle muscles are affected, most commonly in that order. The
extremity and respiratory muscles are also often involved. The
muscle weakness typically fluctuates, being minimal in the
DISCUSSION
This gentleman presented with classical symptoms and signs
of myasthenia gravis (MG). MG is the prototypic neuromuscular
junction disorder. Other entities in this spectrum are Lambert-
Eaton myasthenic syndrome, botulism, congenital MG, familial
infantile MG, and envenomation by cobra or alpha-bungarotoxin.
A transitory form of MG affects 10% to 20% of the newborns
whose mothers have autoimmune MG.
The underlying pathophysiology in MG is distortion and
simplification of the end-plate membrane in the neuromuscular
Figure 1. Ptosis of the left upper
and right lower lid is evident.
Figure 2. Following injection of
the edrophonium chloride, the
ptosis is resolved. The frontal
and nasolabial creases are more
prominent due to improved tone
in the facial muscles.
Gundersen Lutheran Medical Journal • Volume 5, Number 1, July 2008 19