JOURNAL OF THE LOUISIANA STATE MEDICAL SOCIETY
SWINGS IN SODIUM: THE PENDULUMTHAT FOLLOWS PITUITARY GLAND RESECTION
THE DIAGNOSIS OF HUNTINGTON'S DISEASE
A. Singh, MD Department of Medicine, Leonard J Chabert Medical Center, Houma
S. Khateeb, MD; D. Englert, MD Department of Medicine, Ochsner Medical Center, New Orleans, LA
Case: A 37-year-old man with a history of anxiety disorder presented with progressive tics of bilateral upper and lower extremities for the last 9 years. They were associated with a staggering gait and intermittent slurred speech. He denied any recent trauma or injury. There was no known family history of neurodegenerative illnesses. He did not use drugs, rarely drank alcohol and had a 15 pack/year smoking history. He was treated with benztropin, ziprasidone, and duloxetine for his anxiety. He reported that the tics began prior to receiving this therapy. Physical exam was notable for dyskinetic movements of upper and lower extremities bilaterally with 2+ reflexes throughout. A staggering gait was also present. No speech impairment was noted. Differential diagnoses included hereditary neurodegenerative diseases vs acquired (drug/toxin exposure and tardive dyskinesia). MRI was limited secondary to motion artifact. A diagnosis of Huntington’s Disease was made by a positive test for 48 CAG repeats (consistent with full penetrance of disease). Our patient was started on tetrabenazene and underwent family counseling to discuss the ramifications of disease diagnosis and effect on future children. Discussion: Huntington's disease is a neurodegenerative disorder due to CAG repeats on the huntingtin (HTT) gene on chromosome 4p. Often autosomal dominant in nature, it can rarely present as a new mutation. The worldwide prevalence for the disease is estimated to be 2.7 per every 100,000 people, with a greater prevalence in Europeans. Age of onset of the disease is most common within mid-life. This disease is characterized by choreiform movements (face and limbs), which initially may be mild and gradually progresses to widespread and involuntary movements. Hyperreflexia and dystonia are also seen. Anxiety, depression and irritability may occur prior to disease onset. As the disease progresses, dementia often occurs. MRI is often significant for caudate atrophy. Genetic testing is sensitive (98.8%) and specific (100%) of the time. There is currently no cure and no disease modifying therapies are available. Pharmacologic therapy (tetrabenazene, amantadine typical/ atypical antipsychotics) can be used to control choreiform movements as well as psychiatric concerns.
Case: A 24-year-old man underwent trans-sphenoidal hypophysectomy for Rathke’s cleft cyst. In the immediate post-operative period, he developed diabetes insipidus (DI), as evidenced by hypernatremia and dilute polyuria. At discharge on post-operative day 4, his sodium was 145 mmol/L. He was prescribed intranasal desmopressin as needed, but did not use it after he noticed decreased urine output. On post-operative day 8, sodiumwas 125mmol/L. In clinic the same day, he complained of headache and vomiting, prompting hospital admission for treatment of acute hyponatremia. He appeared euvolemic, and urine osmolality was 809 mOsm/kg. Cortisol and TSH were normal. He was treated for presumed syndrome of inappropriate anti-diuretic hormone (SIADH) with fluid restriction; his sodium improved to 132 mmol/L the following day. He was discharged with instructions for fluid restriction. Repeat sodium on post- operative day 15 was 143mmol/L. Discussion: Aberrancies in sodium and water regulation can occur after pituitary surgery. ADH is synthesized in nuclei located in the hypothalamus, transported via axons through the pituitary stalk, and stored in the posterior pituitary. When intra- operative damage occurs to these neuro-hypophyseal axons an initial shock may occur, resulting in decreased ADH release and early DI. This complication usually occurs within the first 48 hours after surgery. Between post-operative days 5-8, degeneration of neuro-hypophyseal axons can occur. Preformed ADH is suddenly released, leading to SIADH. This early DI followed by SIADH is known as the “biphasic” response. Depending on the extent of damage to the neurons, theADHaxismay either return to normal or become persistently dysfunctional, resulting in permanent DI. When the biphasic response is followed by persistent DI, this is termed the“triphasic” response. It is important for internists and endocrinologists to recognize that there may be several phases to water and sodium dysregulation after pituitary surgery. Initiating appropriate management and monitoring for sudden changes is vital to patient safety.
64 J La State Med Soc VOL 170 MARCH/APRIL 2018
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