What is the impact of craniopharyngioma on the sella turcica and surrounding structures?

Craniopharyngioma and Sella Turcica Anatomy

Anatomic Location and Relationship

Craniopharyngiomas are benign embryogenic tumors that primarily arise in the sellar and suprasellar regions, with the sella turcica serving as the anatomic foundation from which these tumors originate or through which they extend. 1, 2

Primary Tumor Origins

• Craniopharyngiomas arise from epithelial remnants of the craniopharyngeal duct or Rathke's pouch (adamantinomatous type) or from metaplastic squamous epithelial cells that are remnants of the stomadeum (squamous papillary type) 1
• These tumors characteristically occupy the sellar, suprasellar, and parasellar regions of the central nervous system 3, 1
• The sella turcica itself can be directly involved, with tumor extension causing sellar expansion and bony remodeling 4

Patterns of Sellar Involvement

• Suprasellar extension is the most common pattern, with tumors growing upward from the sella to compress the optic chiasm and hypothalamus 5, 2
• Infrasellar craniopharyngiomas are extremely rare, with only 35 cases reported in the literature, where tumors originate from the sphenoid bone with extension into the sella turcica 4
• Nasopharyngeal craniopharyngiomas can involve the sella turcica secondarily, though this represents an unusual presentation 6

Impact on Surrounding Structures

Bony Changes to the Sella Turcica

• CT imaging demonstrates that craniopharyngiomas can cause bone-destructive lesions of the skull base affecting the sella turcica 5
• Larger tumors may cause sellar remodeling including sellar enlargement, bony erosion, suprasellar extension, invasion into the clivus, or sphenoid sinus involvement 5
• The characteristic location and bony changes help distinguish craniopharyngiomas from other sellar masses 5

Compression of Neurovascular Structures

• Visual disturbances occur from compression of the optic chiasm by suprasellar tumor extension, representing one of the most common presenting symptoms 3, 1
• Displacement or encasement of vessels in the suprasellar region can occur, requiring MRA for surgical planning 5
• Cavernous sinus invasion may develop, though this is less common than with other sellar masses 5

Endocrine Dysfunction

• Endocrine disturbances are typically permanent and result from compression or invasion of the pituitary gland and hypothalamus 1
• Growth retardation and delayed puberty are common presenting features in children due to disruption of the hypothalamic-pituitary axis 1
• Hypopituitarism develops from mass effect on the pituitary gland within the sella turcica 5

Imaging Characteristics

MRI Findings

• MRI using high-resolution pituitary protocols is the gold standard for evaluating craniopharyngiomas and their relationship to the sella turcica 5, 7
• The neuroradiological diagnosis is based on three tumor components (cystic, solid, and calcified) in the characteristic sellar/parasellar location 1
• Thin-section T1-weighted and T2-weighted sequences with pre- and post-contrast imaging define tumor extent and relationship to critical structures 7

CT Utility

• CT is superior for detecting calcification, which is typical of pediatric adamantinomatous craniopharyngiomas 2
• CT provides essential osseous detail for anatomy in the sphenoid sinus prior to transsphenoidal surgery 5
• Thin-section acquisition with multiplanar reformatting aids intraoperative navigation and demonstrates sellar bony changes 5

Clinical Implications

Presentation Patterns

• Headaches represent the most common neurological symptom at presentation 1
• Visual disturbances occur from suprasellar extension compressing the optic chiasm 3, 1
• Endocrine dysfunction including growth hormone deficiency, delayed puberty, and panhypopituitarism results from sellar and suprasellar involvement 1

Surgical Considerations

• Transsphenoidal resection through the sella turcica is the mainstay of treatment for most craniopharyngiomas 7
• Endoscopic endonasal approaches utilize the natural corridor through the sphenoid sinus to access the sella and suprasellar region 2
• Prechiasmatic/preinfundibular lesions are effectively removed using an endonasal transtuberculum/transplanum approach, while subchiasmatic/transinfundibular tumors require a transellar approach 2

Critical Pitfalls

• Do not delay surgical planning for resectable lesions, as visual recovery is unlikely after the first postoperative month 7
• Avoid attributing all symptoms to the craniopharyngioma without considering the specific anatomic relationships and compression patterns 8
• Do not overlook the need for lifelong endocrine surveillance, as hormonal deficiencies from sellar involvement are typically permanent 7, 1