D J Wake1, J V Lamb2, N Babu3, IW
Campbell2
1 Metabolic Unit,
Western General Hospital, Edinburgh EH4 2XU 2 Department of Medicine
, Victoria Hospital, Kirkcaldy KY2 5AH, 3 Department of Anaesthetics,
Victoria Hospital, Kirkcaldy KY2 5AH
Corresponding Author: Dr Deborah J Wake, Specialist Registrar, Metabolic
Unit, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU
Email:
debbie@thewakesplace.co.uk
ABSTRACT
Thyroid storm (crisis) is uncommon but may be life threatening and is
recognised by an exaggeration of the clinical features of thyrotoxicosis.
Proximal myopathy is a well recognised presenting feature of Graves disease.
Respiratory muscle weakness may also commonly occur in thyrotoxicosis but is
often undiagnosed. We report a case
of thyroid storm with rapid atrial fibrillation, severe agitation and extreme
widespread muscle weakness. The respiratory muscles were so compromised that a
respiratory arrest occurred. Ventilation was required for 7 weeks until full
recovery occurred.
Keywords: Thyroid storm, thyrotoxicosis, ventilation, respiratory
failure, myopathy
CASE HISTORY
A previously fit and well 58 year old shop worker presented as an
emergency with a 3 month history of worsening breathlessness, agitation and
palpitations. She was noted to have bilateral lid retraction and exopthalmos,
(more so on the right than the left). She
was pyrexial (38.5C), with a rapid irregular pulse of 200 beats per minute,
confirmed on ECG as atrial fibrillation. She was markedly dyspnoeic at rest with
arterial blood gases confirming type 1 respiratory failure (pO2 -7.9kPa, pCO2
-5.9kPa, O2 sats of 77% on air). Blood Pressure was 140/100mmHg. The clinical
impression of a thyroid storm was confirmed by a markedly elevated free
thyroxine (T4; 360pmol/L (ref range 9-19)) with an undetectable TSH. Later the
TSH receptor stimulating antibodies (TRABS) were elevated at 11.2 u/L (normal
range 0 – 1.5u/L) confirmed Graves disease. Urea and electrolytes were normal
with no evidence of hypokalaemia. She was admitted initially to the coronary
care unit for control of the atrial fibrillation with intravenous propranolol,
digoxin, oral carbimazole and iodine aqueous solution.
Her
condition deteriorated with the first hour, with hypoventilation, hypoxia (pO2-6.9kPa,
pCO2-5.4kPa, pH-7.42; O2 stats 86% (on 70%O2) and
hypotension (BP- 80/40mmHg). An echocardiogram could not be interpreted because
of the rapid ventricular rate. The patient was markedly hypotonic, unable to
support herself upright in bed and she could not lift her head to look straight
ahead. She was transferred to the intensive care unit for consideration of
ventilation and on route suffered a respiratory arrest with a brief episode of
asystole, which responded to a ‘thump’ on the sternum, returning a rhythm of
fast atrial fibrillation. She was intubated within 3 minutes and ventilation
started.
Seven
weeks of ventilation, five weeks of which required inotropic support, followed
by a five week period of rehabilitation led to a full recovery. Pulmonary
function tests were not performed at presentation but this non-smoker had a
FEV1/FVC of 78% predicted and a total lung capacity was 4.05 litres (predicted
4.58 litres) on recovery. The echocardiogram showed normal left ventricular
function at this stage. The patient was discharged on carbimazole 20mg twice
daily, propranolol 40mg twice daily with atrial fibrillation controlled at 80
beats per minute. Dalteparin was used for anticoagulation whilst ventilated and
warfarin commenced prior to discharge. Some 18 months later, she was well, back
at work and her euthyroid status maintained on carbimazole 20mg daily.
Discussion
Peripheral
myopathies are not uncommon in hyperthyroidism and are thought to be
inflammatory in nature (1, 2) and possibly part of a polymyositis spectrum (3).
Hypokalaemic periodic paralysis is a rare complication of thyrotoxicosis in
Caucasians, but seen in around 2% of patients of Chinese and Japanese origin.
This affects mainly peripheral muscles and usually spares the respiratory system
(4,5). In general, in hyperthyroidism, muscle mass and strength including both
upper and lower limb girdle muscles and muscles of respiration may be reduced by
approx 20 and 40% respectively (6). Hypoventilation may occur, associated with
diaphragmatic and intercostal muscle weakness, which is reversible with
treatment (7,8). We can find no other reports in the literature of prolonged
ventilation being necessary for full recovery from type 1 respiratory failure
associated with thyroid storm. The exact pathophysiology is unclear, but
reduction in muscle mass, dysynergia of the thoracic diaphragm and changes in
adrenergic muscle stimulation may contribute.
The
cardiovascular system is also directly and indirectly affected by thyrotoxicosis
(9), with dysrhythmias (notably atrial fibrillation) or worsening of ischaemic
heart disease symptoms. Acutely, thyrotoxicosis increases cardiac output through
increased contractility and improved diastolic function. Over time however left
ventricular hypertrophy and cardiac failure may occur. Acute cardiomyopathies
have also been described in thyrotoxic states. These may present with sudden
pulmonary oedema and are reversible upon treatment of thyrotoxicosis (10,11).
Milder abnormalities of left ventricular function with no cardiac symptoms have
been reported which took up to six weeks to reverse following the establishment
of the euthyroid state (12). The patient described had rapid atrial fibrillation
and the hypotension associated with the respiratory arrest may have been due to
left ventricular dysfunction, but echocardiogram was inconclusive at diagnosis,
and at six weeks showed normal findings.
In conclusion, cardiac symptoms e.g. palpitations are well recognised in
thyrotoxic patients. Dyspneoa occurs in about 80% of such patients and is
usually attributed to cardiac causes e.g. uncontrolled atrial fibrillation, but
may be due to weakness of diaphragmatic and intercostal muscles. This should be
kept in mind when assessing all thyrotoxic patients, not just those presenting
in extremis with hypoventilation and type 1 respiratory failure as described. If
ventilation is required in such exceptional circumstances, then it may have to
be prolonged. In the case described it was seven weeks before the ventilation
could be safely discontinued.
The patient has given full consent for her case details and images to be
used in this publication.
References
1. Cakir M, Samanci N, Balci N, Balci
MK. Musculoskeletal manifestations in patients with thyroid disease. Clin
Endocrinol (Oxf). 2003; 59: 162-7.
2. Hardiman O, Molloy F, Brett F, Farrell M. Inflammatory
myopathy in thyrotoxicosis. Neurology.
1997; 48: 339-41.
3. Russo S, Ombricolo E, Papadopoulou O,
Paggi A [Dilated myocardiopathy and polymyositis. A clinical case and critical
review of the literature] Clin Ter.
1997; 148: 57-64
4.
Lin SH. Thyrotoxic periodic paralysis. Mayo
Clin Proc. 2005; 80(1):
99-105
5.
Kung AW. Clinical review: Thyrotoxic periodic paralysis: a diagnostic challenge J
Clin Endocrinol Metab. 2006: 91(7): 2490-5
6.
Norrelund
H, Hove KY, Brems-Dalgaard E, Jurik AG, Nielsen LP, Nielsen S, Jorgensen JO,
Weeke J, Moller N. Muscle mass and function
in thyrotoxic patients before and during medical treatment. Clin Endocrinol (Oxf). 1999; 51(6): 693-9.
7.
Goswami
R, Guleria R, Gupta AK, Gupta N, Marwaha RK, Pande JN, Kochupillai N.
Prevalence of diaphragmatic muscle
weakness and dyspnoea in Graves' disease and their reversibility with
carbimazole therapy. Eur J
Endocrinol. 2002; 147(3): 299-303
8.
McElvaney
GN, Wilcox PG, Fairbarn MS, Hilliam C, Wilkins GE, Pare PD, Pardy RL.
Respiratory muscle weakness and
dyspnea in thyrotoxic patients. Am Rev Respir Dis.1990; 141(5 Pt 1): 1221-7.
9.
Roffi M, Cattaneo F, Topol EJ. Thyrotoxicosis and the cardiovascular system;
Subtle but serious effects. Cleveland
Clinical Journal of Medicine. 2003; 70 (1); 57-63
10. Russo S, Ombricolo E, Papadopoulou O, Paggi A. [Dilated myocardiopathy and polymyositis. A clinical case and critical review of the literature]. Clin Ter.1997; 148(1-2):57-64.
11.
Goland, S. Shimoni, S., Kracoff, O. Dilated Cardiomypathy in thyrotoxicosis Heart.
1999; 81; 444-445
12.
Forfar JC,
Muir AL,
Sawers SA,
Toft AD.
Abnormal left ventricular function in
hyperthyroidism: evidence for a possible reversible cardiomyopathy. N
Engl J Med. 1982; 307(19): 1165-70.