Acute Flaccid Paralysis Accompanying West Nile Meningitis Ahmed ...

An Uncommon Cause of a Common Symptom
Peters, C, D.O., Tepper, S, D.O.
Kent Hospital, Warwick, RI
Introduction: In both the inpatient and outpatient setting, chief complaints of weakness
and falls are a common encounter. However, when a previously healthy young male
presents with these complaints, a broad differential must be considered.
Case: A 28 year old Caucasian male with a past medical history of lumbar spinal
schwannoma presented as a new patient to his primary care physician’s office with
complaints of progressively worsening bilateral thigh weakness with multiple falls. Over
the two weeks prior to presentation, he had been seen at an urgent care as well as the
ED two separate times for evaluation of his symptoms. His work-up, including head CT
and laboratory data, had been interpreted as normal and he received no treatment, with
the exception of a referral to an outpatient primary care physician. At his new PCP’s
office, he complained of headaches, difficulty with vision out of his left eye with
associated tearing, as well as hand tremor. Further review of systems revealed
shortness of breath and palpitations. His family history was significant for
hyperthyroidism in his mother. On exam his vitals were unremarkable, with the exception
of a pulse rate of 121 beats per minute. While he was noted to have 5/5 strength
throughout his upper and most of his lower extremities, he had only 4/5 strength in his
proximal thigh muscles. His laboratory data from his previous ED visits were reviewed,
including a thyroid stimulating hormone (TSH) level that was mildly decreased at 0.09
mcl Unit/ml (normal 0.30-5.60) and a serum potassium level of 3.4 mmol/L (normal 3.6-
5.0). A follow-up free thyroxine level was ordered and was found to be 2.85 ng/ml
(normal 0.58-1.64), consistent with hyperthyroidism. Taking into consideration his
weakness and hypokalemia, the suspicion for thyrotoxic periodic paralysis was raised.
He was started on methimazole and atenolol and was referred to endocrinology and
neurology for further evaluation. Diagnosis of thyrotoxic periodic paralysis was
confirmed. The patient continued to have debilitating weakness despite increasing doses
of methimazole and potassium replacement. He eventually underwent radioactive
ablation of the thyroid under the care of endocrinology and was started on thyroid
replacement therapy with levothyroxine. His symptoms significantly improved.
Discussion: This patient was diagnosed with hyperthyroidism and thyrotoxic periodic
paralysis (TPP). Hyperthyroidism can present in many ways and with different
constellations of symptoms. Our patient’s presenting symptom of weakness, combined
with hypokalemia and hyperthyroidism, led to a diagnosis of TPP. The prevalence of
TPP in the Caucasian population is not well documented and there have only been a
limited number of case reports in the literature. TPP is more common in the Asian
population where up to two percent of patients diagnosed with hyperthyroidism also
have TPP. The mechanism of hypokalemia is not well understood. It has been
suggested that thyroid hormone could have an effect on calcium channels or sodiumpotassium
pumps. Therapy includes treating the underlying hyperthyroidism, using
potassium supplementation as needed, and following a low carbohydrate diet.
Diagnosis is critical as proper treatment usually ensures complete recovery.