Hypoparathyroidism can complicate subtotal and total thyroidectomy if all parathyroid glands are inadvertently removed. Transient hypocalcemia can complicate 20-40% of patients beginning in 12h-36 h after total thyroidectomy, usually asymptomatic. Temporary hypoparathyroidism usually resolves in days, weeks, or a few months. When it lasts more than six months it is permanent hypoparathyroidism. According to some authors, the rate of permanent hypoparathyroidism should be no more than 1-2%. Possible presentations of hypocalcemia are:
Chvostek sign
Trousseau sign
Seizures
Irritability
Confusion
Anxiety
Circumoral paresthesia
Depression
Tetany
Cramps
Arrhythmia
Tachycardia
Hypotension
Neurological symptoms are possible in a patient with hypoparathyroidism. In that setting, I found an interesting paper about one rare disease that can complicate a patient submitted to total thyroidectomy, Fahr’s syndrome. It was published by Mahmood et al from Rawalpindi Medical University and Allied Hospitals, Rawaldi, Pakistan.
The authors present a case of a 56 yo woman who presented to the emergency department with tonic-clonic seizures, dysphagia, and insomnia. The symptoms were progressively worsening during the previous year, associated with changes in overall behavior and dysarthric speech. She had been put on anti-epileptics by a neurologist, but symptoms kept worsening. A subtotal thyroidectomy 25 years before was the only relevant past medical history. Blood tests revealed a low PTH of 8.2 pg/ml (15-65 pg/ml) and low total calcium of 5.4 mg/dl (8.4-10.6 mg/dl). A brain CT scan showed calcifications of the basal ganglia, thalamus, and cerebellar nuclei. Diagnosis of Fahr’s syndrome secondary to post-thyroidectomy hypoparathyroidism was made. She initiated oral calcium and vitamin D supplementation and symptoms improved.
Although usually idiopathic, there are two forms of Fahr’s syndrome (or Fahr’s disease) based on possible etiology. Primary Fahr’s syndrome is a rare degenerative neurological disorder, usually autosomal dominant, without any known etiology (idiopathic), with both sporadic and familial cases reported. Secondary Fahr’s syndrome can be associated with endocrine conditions (e.g., secondary hypoparathyroidism), infectious diseases (e.g., intrauterine and perinatal infections, tuberculosis), and inherited syndromes (e.g., Aicardi-Goutières syndrome, Coats plus syndrome - definitions in the bottom). Important to know is that brain calcium deposition starts three decades before the arising of clinical presentation. In my opinion, this is very important data, since Fahr’s syndrome will not clinically arise in the few years following a total thyroidectomy complicated with hypoparathyroidism. This means that a long-time follow-up by an endocrinologist or general practice doctor will be necessary after total thyroidectomy. Additionally, I believe this is to be considered in permanent postoperative hypoparathyroidism.
Fahr’s syndrome has an incidence of <1 per million and is characterized by symmetrical calcifications of specific brain areas connected to movement control (e.g., basal ganglia, dentate nuclei, putamen, thalamus, cerebral cortex, subcortical white matter, hippocampus, and cerebellum). Clinical presentation varies depending on the brain areas affected. According to the authors, there are several diagnostic criteria:
Neurological and psychiatric symptoms (degenerative symptoms can be present)
Age of onset around fourth – sixth decades of life
CT with bilateral basal ganglia (or other areas) calcification
Absence of other causes of brain calcification
Treatment of this rare syndrome is based on the corrections of metabolic disorders such as low calcium levels. Mahmood et al “recommend CT imaging and measurement of serum calcium levels as part of the long-term follow-up of patients after thyroidectomy”. Is this necessary? Is there a true need to perform a CT scan on all patients after subtotal and total thyroidectomy? If the patient is diagnosed with permanent hypoparathyroidism, I do believe doctors should be aware of this neurological complication. In that setting, a long-term follow-up with neurological evaluation and calcium serum levels measurements should be conducted.
Rare diseases definitions:
Aicardi-Gutières syndrome - inherited encephalopathy with calcification of basal ganglia, causing neurological and liver abnormalities; it has an early-onset form with more severe symptoms and a late-onset form with less impact on neurological function.
Coats plus syndrome - a multisystemic disease with retinal telangiectasia, brain calcifications, brain cysts, gastrointestinal bleeding, and portal hypertension.
Link to PubMed:
Dr. Carlos Eduardo Costa Almeida
General Surgeon