Pituitary gland enlargement secondary to dural arteriovenous fistula in the cavernous sinus: appearance at MR imaging

Pituitary enlargement in a carotid-cavernous fistula: An atypical imaging manifestation

A carotid-cavernous fistula is a rare abnormal communication between carotid vasculature and the cavernous sinus. Development of a carotid-cavernous fistula often results from trauma, but may be spontaneous in the setting of predisposing risk factors. Suspicion for a spontaneous fistula is understandably low on routine non-contrast imaging. In this article, we present a case of a carotid-cavernous fistula initially presenting with the potentially underrecognized imaging manifestation of diffuse pituitary enlargement identified on a non-contrast CT, later revealed to be due to the presence of the fistula.

The Morphology of the Pituitary Gland: A Meta-Analysis with Implications for Diagnostic Imaging

The objective of this meta-analysis was to present transparent data on the morphology of the pituitary gland (PG) using the available data in the literature. The main online medical databases, such as PubMed, Embase, Scopus, and Web of Science, were searched to gather all relevant studies regarding PG morphology. The mean overall volume of the PG was found to be 597.23 mm³ (SE = 28.81). The mean overall height of the PG was established to be 5.64 mm (SE = 0.11). The mean overall length of the PG was found to be 9.98 mm (SE = 0.26). In the present study, the PG's overall morphology and morphometric features were analyzed. Our results showed that, on average, females from Asia have the highest volume of PG (706.69 mm³), and males from Europe have the lowest (456.42 mm³). These values are crucial to be aware of because they represent the normal average properties of the PG, which may be used as reference points when trying to diagnose potential pathologies of this gland. Furthermore, the present study's results prove how the PG's size decreases with age. The results of the present study may be helpful for physicians, especially surgeons, performing procedures on the PG.

The inferior intercavernous sinus: An anatomical study with application to trans-sphenoidal approaches to the pituitary gland

OBJECTIVES

The inferior intercavernous sinus is located below the pituitary gland in the sella turcica. Its presence has been controversial among anatomists because it is not always found on radiological imaging or during cadaveric dissections; however, it is becoming a better-known structure in the neurosurgical and radiological fields, specifically with respect to transsphenoidal surgery. Therefore, the present study was performed to better elucidate this structure at the skull base.

PATIENTS AND METHODS

Fifty adult, latex injected cadavers underwent dissection. The presence or absence of the inferior cavernous sinus was evaluated and when present, measurements of its width and length were made. Its connections with other intradural venous sinuses were also documented.

RESULTS

An inferior intercavernous sinus was identified in 26 % of specimens. In all specimens, it communicated with the left and right cavernous sinus. The average width and length were 3 mm and 9.5 mm, respectively. In the sagittal plane, the inferior intercavernous sinus was positioned anteriorly in 31 %, at the nadir of the sella turcica in 38 %, and slightly posterior to the nadir of the sella turcica in 31 %. In two specimens (15.4 %), the sinus was plexiform in its shape. In one specimen a diploic vein connected the basilar venous plexus to the inferior intercavernous sinus on its deep surface.

CONCLUSION

An improved understanding of the variable anatomy of the inferior intercavernous sinus is important in pathological, surgical, and radiological cases.

Bilateral Carotid-Cavernous Fistulas: An Uncommon Cause of Pituitary Enlargement and Hypopituitarism

Carotid-cavernous fistulas (CCFs) are rare, pathologic communications of the carotid artery and the venous plexus of the cavernous sinus. They can develop spontaneously in certain at risk individuals or following traumatic head injury. Typical clinical manifestations include headache, proptosis, orbital pain, and diplopia. We report a case of bilateral carotid-cavernous fistulas associated with these symptoms and also with pituitary enlargement and hypopituitarism, which improved following surgical intervention. Arterialization of the cavernous sinus and elevated portal pressure may interfere with normal venous drainage and the conveyance of inhibiting and releasing hormones from the hypothalamus, resulting in pituitary enlargement and hypopituitarism. This condition should be considered in the differential diagnosis of hypopituitarism associated with anterior pituitary enlargement.

Dural Venous System in the Cavernous Sinus: A Literature Review and Embryological, Functional, and Endovascular Clinical Considerations

The cavernous sinus (CS) is one of the cranial dural venous sinuses. It differs from other dural sinuses due to its many afferent and efferent venous connections with adjacent structures. It is important to know well about its complex venous anatomy to conduct safe and effective endovascular interventions for the CS. Thus, we reviewed previous literatures concerning the morphological and functional venous anatomy and the embryology of the CS. The CS is a complex of venous channels from embryologically different origins. These venous channels have more or less retained their distinct original roles of venous drainage, even after alterations through the embryological developmental process, and can be categorized into three longitudinal venous axes based on their topological and functional features. Venous channels medial to the internal carotid artery "medial venous axis" carry venous drainage from the skull base, chondrocranium and the hypophysis, with no direct participation in cerebral drainage. Venous channels lateral to the cranial nerves "lateral venous axis" are exclusively for cerebral venous drainage. Venous channels between the internal carotid artery and cranial nerves "intermediate venous axis" contribute to all the venous drainage from adjacent structures, directly from the orbit and membranous skull, indirectly through medial and lateral venous axes from the chondrocranium, the hypophysis, and the brain. This concept of longitudinal venous axes in the CS may be useful during endovascular interventions for the CS considering our better understandings of its functions in venous drainage.

Development of syndrome of inappropriate antidiuretic hormone secretion (SIADH) after Onyx embolisation of a cavernous carotid fistula

Patients with cavernous carotid fistulas (CCFs) can present with pituitary hypoperfusion and hypopituitarism; however, there are no previous reports of pituitary or hormonal abnormalities developing after CCF embolisation in an asymptomatic patient. We describe a patient with no hormonal abnormalities who developed syndrome of inappropriate antidiuretic hormone (SIADH) secretion after CCF embolisation. The patient had bilateral indirect CCFs, which were completely embolised via a transvenous approach, and was neurologically stable postoperatively and discharged. In the subsequent 2 weeks the patient was readmitted twice for acute hyponatraemia and a tonic-clonic seizure. Laboratory studies revealed severe SIADH. Clinical status and sodium levels improved after treatment. One year later the patient was weaned off all medications and remained neurologically stable. SIADH may be a delayed phenomenon after CCF embolisation. Given the proximity of embolised vessels to the pituitary's vascular supply, CCF treatment may result in flow disturbance, ischaemia and hormonal abnormalities.

Development of syndrome of inappropriate antidiuretic hormone secretion (SIADH) after Onyx embolisation of a cavernous carotid fistula

Patients with cavernous carotid fistulas (CCFs) can present with pituitary hypoperfusion and hypopituitarism; however, there are no previous reports of pituitary or hormonal abnormalities developing after CCF embolisation in an asymptomatic patient. We describe a patient with no hormonal abnormalities who developed syndrome of inappropriate antidiuretic hormone (SIADH) secretion after CCF embolisation. The patient had bilateral indirect CCFs, which were completely embolised via a transvenous approach, and was neurologically stable postoperatively and discharged. In the subsequent 2 weeks the patient was readmitted twice for acute hyponatraemia and a tonic-clonic seizure. Laboratory studies revealed severe SIADH. Clinical status and sodium levels improved after treatment. One year later the patient was weaned off all medications and remained neurologically stable. SIADH may be a delayed phenomenon after CCF embolisation. Given the proximity of embolised vessels to the pituitary's vascular supply, CCF treatment may result in flow disturbance, ischaemia and hormonal abnormalities.

Hypopituitarism caused by carotid cavernous fistula

Here we report a 79-year-old woman who presented with a 7-day history of headache, nausea, vomiting, and was found to have proptosis and ptosis. Laboratory findings showed hyponatremia, hypocortisolism, secondary hypothyroidism and low follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels. CT angiography (CTA) showed a vascular lesion in sella causing a mass affect on the pituitary gland which proved to be a carotid cavernous fistula (CCF) by conventional angiography. The lesion was subsequently treated with coil placement and patient's hyponatremia was successfully treated with corticosteroid and thyroid hormone replacement. Though rare, CCF should be considered in the differential diagnosis of sellar lesions. Also, in patients with CCF hyponatremia, hypotension or signs of hypothyroidism should warrant a work-up for pituitary function.

Imaging diagnosis and fundamental knowledge of common brain tumors in adults

The most common primary brain tumors in Japanese adults are meningiomas, gliomas, pituitary adenomas, and schwannomas, which together account for 84.0% of all primary brain tumors. The typical imaging findings of these tumors are well known by radiologists; therefore, the clinical and pathological issues, including terminology, genetics, and relation to hormones are discussed in this article. Other diseases important for the differential diagnoses are also mentioned. The molecular genetic analysis of brain tumors has recently become important. For instance, genetic analysis is important for differentiating oligodendroglial tumors from astrocytic tumors, and the gene mutation predicts response to chemotherapy for anaplastic oligodendrogliomas. Background factors such as hormones, history of cranial irradiation, and medications influence oncogenesis, tumor growth, and tumor appearances as seen by imaging modalities. A differential diagnosis with knowledge of the above may have some advantages over diagnoses based on imaging findings alone. Nonneoplastic diseases such as abscesses and demyelinating diseases may mimic gliomas. Pituitary adenomas may be confused with nonneoplastic conditions such as physiological hypertrophy and Rathke's cleft cyst. Such misdiagnoses would result in a treatment protocol very different from what would be suitable. Such conditions should be carefully distinguished from neoplasms.

[Hormonal dysfunction of nonpituitary lesions from midline and perisellar area]

OBJECTIVE

To analyse clinical and/or laboratorial preoperative hormonal dysfunction, of the nonpituitary intracranial lesions from midline and parasellar area.

METHOD

Forty-four patients were evaluated with nonpituitary intracranial lesions, who had images studies (computed tomography or magnetic resonance) and preoperative basal hormonal level; 16 had preoperative hypothalamus-hypophysial function tests (megatests). These patients were divided in two groups. Group I - 34 lesions from midline: 11 craniopharyngiomas, 8 meningiomas, 3 germinomas, 3 tumors of sphenoid sinus, 2 empty sella syndrome, 2 pylocitic astrocytomas, 1 giant aneurysm, 2 mucoceles, 1 III ventricle diverticulum and 1 Rathke's cleft cyst; Group II - 10 lesions from parasellar area: 9 meningiomas and 1 giant aneurysm.

RESULTS

In group I, 25/34 (73.5%) patients showed laboratorial hormonal deficit (14 without clinical manifestations) 18/34 (52.9%) hyperprolactinemia (5 with galactorreia) and 8 (53.3%) showed growth hormone deficiency in 15 megatests available in this group; 3 (8.8 %) patients presented central diabetes insipidus (CDI). In group II, 6/10 (60%) patients showed laboratorial hormonal deficit (5 without clinical manifestations), 1 (10%) hyperprolactinemia and 1 growth hormone deficiency (single megatest realized in this group); no patient had preoperative CID.

CONCLUSIONS

The presence of nonspecific or poorly valorized clinical manifestations, does not indicate absence of hormonal dysfunction; in this present serie, 19/38 (50%) patients with laboratorial abnormalities, didn't show clinical manifestations. Hormonal dysfunction is frequent in sellar and perisellar nonpituitary lesions, specially involving midline.

Current approaches to imaging of the sellar region and pituitary

Recent advances in MR imaging have enabled the radiologist to view the pituitary gland in its normal and diseased states to a greater extent than ever before. The techniques for obtaining quality images of the sellar region and the normal appearance of the pituitary gland are discussed. This article also discusses the imaging of several pituitary disease processes, with emphasis on pitutiary adenomas and recent advances in diagnosis and follow-up. Current controversies also are addressed.