Extrapontine Myelinolysis and Pituitary Tumor Apoplexy in Pregnancy
Background
Pituitary tumor apoplexy (PTA) is an uncommon but potentially fatal clinical emergency resulting from abrupt ischemic infarction or hemorrhage of the pituitary tumor. A variety of precipitating factors has been linked to PTA, including pregnancy. However, gestational pituitary apoplexy is limited to isolated case reports and very small case series.
In this article, a case report of pituitary apoplexy associated with extrapontine myelinolysis during pregnancy is presented. The aim was to provide a rational framework for the diagnostic and therapeutic management of gestational pituitary apoplexy in women.
Patient Consent
This study was approved by Soochow University’s Ethics Committee. The patient consented to the publication of the data in writing.
Case Report
A 32-week pregnant female, 24 years old, presented to The Third Affiliated Hospital of Soochow University, Changzhou (Jinhua, China) with a complaint of frequent vomiting for 3 days. She described having a low fever but there was no abdominal pain or diarrhea. She denied having any other discomforts and thought of it as common flu or upper respiratory tract infection. On Dec 10th, 2018, she had severe persistent episodes of fatigue and vomiting.
Arterial blood gas (ABG) analysis revealed high levels of serum sodium at 111.6mmol/L, and chlorine at 91.3mmol/L. The plasmatic osmolality of the patient was 226m Osm 226/kg. Blood electrolyte test revealed serum sodium concentration as 116.7mmol/L, chlorine concentration as 87.3mmol/L, and potassium as 4.52mmol/L. She was given 400ml 3% NaCl by intravenous infusion. The next day, another 400ml of 3% NaCl was intravenously administered as the blood electrolyte retest showed a spike in serum sodium concentration (126.0mmol/L). Unfortunately, she developed aphasia and hemiplegia on the right limb in the noon, so she was immediately admitted to the obstetric department.
After obstetric admission, she was afebrile (temp. 36.6°C ); her heart rate was 101bpm and her blood pressure was 122/77mmHg. Physical examination revealed a shallow right nasolabial groove and her tongue was found to be extended to the right direction. However, her visual field detection was normal. The MRC scale of muscle strength showed her right upper limb power as 0/5, right lower limb power as 3/5, and left limb power as 4/5 – meaning she was retarded with hemiplegia on the right side. Pain sensitivity was lower on the right side than that on the left side. All her deep tendon reflexes were positive; the plantar response was positive on the right. What was remarkable about her obstetrical examinations was that the 32-week old gravid uterus had a normal fetal heart rate.
Magnetic resonance imaging (MRI) of the cerebrum showed a sellar mass with an abnormal size of about 15x14x14mm, a clear indication of pituitary tumor apoplexy. There were abnormal signals in the corpus callosum, bilateral basal ganglia, and centrum semiovale. There was no abnormality in magnetic resonance angiography and venography. The results of immediate lab tests and ABG analysis were as follows: pH 7.31; blood oxygen saturation 98.8%; CO2 partial pressure 23.10mmHg; plasmatic osmolality 252Osm 226/kg; blood glucose 2.8mmol/l; lactic acid <1mmol/L. Blood routine showed hemoglobin was 11.5mg/dl and platelet was 248 × 109/L. The biochemical test showed 131.6mmol/L of Na, 12.3mmol/L of CO2, 1.0 mmol/L BUN, 45U mol/L of creatinine, 63m/L of blood amylase, 119m/L of blood lipase, and 6.01 g/L of fibrinogen.
The patient’s hormone profile revealed plasma prolactin (PRL) 104.71 ng/ml (3.34– 26.72 ng/ml), TSH 1.49mIU/ml (0.3–5.5mIU/ml), fT4 11.26 pmol/L (11.46–23.17 pmol/L), fT3 3.52 pmol/L (2.8–7.1 pmol/L), and growth hormone 0.65 ng/ml (0.06–5ng/ml). ACTH at 8AM and 4PM were 9.53 pg/ml (6–40 pg/ml) and 7.12 pg/ml (3–30 pg/ml) respectively. Cortisol levels at 8AM and 4PM were 15.46mg/dl (6.7–22.8) and >61.4mg/dl (0–10mg/dl) respectively. The high cortisol levels at 4PM indicated hydrocortisone.
The patient’s medical history revealed irregular periods since her menarche at 14-years old. The patient revealed that she had done hormone profiling 2 years before pregnancy and the results were normal; she had not taken any other tests until she was pregnant. She experienced a severe headache during the early days of pregnancy and took painkillers but stopped them considering the negative outcomes of the medication on the fetus. After admission, she has undergone hydrocortisone therapy along with 25mg oral levothyroxine per day; her headache and vomiting improved after 2 days and she regained language skills and limb movement.
MRI after 8 days of admission showed significant improvement in the signal intensity in the splenium of the corpus callosum, bilateral basal ganglia, and centrum semiovale. Delivery by cesarean at 38 +1 week was uncomplicated and she gave birth to a healthy 2.85kg baby. The Apgar score was 9 in the first and fifth minutes. The blood volume during cesarean was 1000ml. She didn’t breastfeed after delivery.
Postpartum, the patient did not have a headache and vomiting except irregular periods. A follow-up magnetic resonance imaging 8 months postpartum showed regression of the pituitary tumor. Furthermore, hormone profiling showed normal levels of TSH, serum cortisol, ACTH, GH, and IGF-1; PRL levels also gradually decreased to 44.59ng/ml.
Discussion
Pituitary tumor apoplexy and pregnancy
The true incidence of pituitary tumor apoplexy in pregnant women is not known; however, it is important to discuss it because of the physiologic changes that occur in the pituitary gland during pregnancy. Gonzalez et al. reported that while pituitary apoplexy can occur in pregnant women with an underlying adenoma, it can also occur due to the enlargement of the pituitary gland during pregnancy and the postpartum period. It is suggested that this increase in size may elevate intracapsular pressure, leading to infarction and hemorrhage and resulting in clinical symptoms. Some studies reported a history of irregular periods in women with pituitary tumors; this was later linked to the elevated levels of prolactin, a pituitary hormone responsible for lactation.
The main symptom of pituitary tumor apoplexy is a sudden and severe headache with vomiting, visual field defects, signs of altered levels of consciousness, and/or endocrine dysfunction. Some authors reported that in the context of pregnancy, the diagnosis of PA can be challenging and the symptoms may be confused with other conditions such as electrolyte imbalance, hyperemesis, or pre-eclampsia.
The patient of this study also had a severe headache and vomiting. Unfortunately, her earlier diagnosis was inaccurate because both symptoms are common during pregnancy. She vomited for 3 days and was administered sodium supplement immediately after hyponatremia diagnosis.
Pituitary tumor apoplexy and Neuroimaging
MRI is the modality of choice for identifying pituitary lesions and extrapontine myelinolysis (EPM). In patients with pituitary apoplexy, MRI shows typical heterogeneous intrasellar or suprasellar lesions, and hemorrhage. Neuroimaging can also show cavernous sinus infiltration and optic chiasm compression in patients. EPM is often associated with an overreaction of hyponatremia. Extrapontine myelinolysis (EPM) and central pontine myelinolysis (CPM) can occur due to changes in serum osmolality and are referred to as osmotic demyelination syndrome (ODS). Yuya et al. reported an incidence of ODS triggered by pituitary apoplexy in a 67-year-old woman with a residual tumor of nonfunctioning pituitary adenoma (NFPA). The authors reported that though their patient was given saline to correct hyponatremia, the overly rapid correction led to transient hemiplegia and aphasia. A cerebral MRI of the patient showed a sellar mass and abnormal signal intensities. These findings were highly suggestive of pre-existing pituitary tumor apoplexy.
Pituitary tumor apoplexy: Surgery vs Conservative management
Management of pituitary tumor apoplexy depends on the state of the patient, clinical assessment, and MRI results. If the patient is alert and has mild dysmotility, conservative methods may be appropriate. The first-line treatment includes IV fluids, blood transfusions, and hydrocortisone administration. In some cases, corticosteroid therapy alone may be sufficient. If the patient has visual or cognitive dysfunction, endocrinological support is required. Some studies indicated that early surgery – within 8 days of onset – significantly improves visual acuity than delayed surgery.
There are no clear guidelines for treating gestational pituitary apoplexy. In the case of prolactinoma and non-stroke symptomatic tumor growth, dopamine agonist therapy is recommended in pregnant women. When Initial management with intravenous glucocorticoid therapy or fluid and electrolyte replacement fails, the choice of medical or surgical treatment is made. Neuro-ophthalmic complications such as visual fields (VF) and visual acuity (VA) impairment are an indication for decompressive surgery in most cases. Surgery is also offered in the presence of abnormal visual or neurological signs or further enlargement of the sellar mass on MRI. Impaired consciousness is another indication of surgical intervention.
Conclusion
The prognosis of pituitary tumor apoplexy during pregnancy depends on the timely diagnosis and appropriateness of the management during the acute and subacute phases of the disease.
Pituitary tumor apoplexy during pregnancy is rare, but the diagnosis should be suspected in all cases with sudden, severe headaches with or without visual disturbances.
In many cases, it is a fatal medical emergency that requires a multidisciplinary approach, which involves endocrinologists, radiologists, neurosurgeons, and neuro-ophthalmologists.
Finally, long-term follow-up is necessary to reassess pituitary function, because of the risk of tumor regrowth.
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