Add comprehensive articles on Vascular Dementia and Wallerian Degeneration

- Created a detailed article for Vascular Dementia covering key facts, terminology, imaging findings, differential diagnoses, pathology, clinical issues, and diagnostic checklist.
- Developed an extensive article on Wallerian Degeneration including key facts, terminology, imaging features, differential diagnoses, pathology, clinical issues, and diagnostic checklist.

docs_md/articles/empty-sella_39a0d2d1-1439-4558-8f5d-86a2a6d93e3a.md

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+---
+title: "Empty Sella"
+docid: "39a0d2d1-1439-4558-8f5d-86a2a6d93e3a"
+breadcrumbs:
+  - "Brain"
+  - "Diagnosis"
+  - "Anatomy-Based Diagnoses"
+  - "Sella and Pituitary"
+  - "Miscellaneous"
+  - "Empty Sella"
+---
+# KEY FACTS
+
+- ## Terminology
+  
+  
+    - Sella partially filled with arachnoid-lined CSF collection
+    - Primary empty sella
+          - Common normal variant (15% of brain MRs), incidental finding
+          - Normal or increased CSF pressure
+          - Near-normal volume of compressed pituitary tissue
+    - Secondary empty sella
+          - Prior pituitary surgery, radiation, or injury
+- ## Imaging
+  
+  
+    - Intrasellar CSF, pituitary flattened against sellar floor
+          - Bony sella may be normal or moderately enlarged (secondary to pulsatile CSF)
+          - Bony margins intact, not eroded/demineralized
+          - Infundibular stalk, pituitary gland enhance normally
+    - Fluid exactly like CSF
+          - Suppresses completely on FLAIR
+          - Does not restrict on DWI
+- ## Top Differential Diagnoses
+  
+  
+    - Idiopathic intracranial hypertension
+    - Secondary intracranial hypertension
+    - Arachnoid cyst
+    - Pituitary apoplexy
+    - Pituitary anomalies
+- ## Pathology
+  
+  
+    - "Deficient" diaphragma sellae
+          - Dural covering of sella is incomplete (widened)
+          - Leaves large opening for infundibular stalk
+          - Allows intrasellar herniation of arachnoid with CSF from suprasellar subarachnoid cistern above
+- ## Clinical Issues
+  
+  
+    - Mostly incidental, asymptomatic (adults)
+          - F:M = 5:1
+    - Headache, visual disturbances if related to intracranial hypertension
+    - Frequent endocrine abnormalities in children
+
+# TERMINOLOGY
+
+- ## Abbreviations
+  
+  
+    - Empty sella (ES)
+- ## Definitions
+  
+  
+    - Herniation of suprasellar arachnoid and cerebrospinal fluid (CSF) through wide diaphragma sellae into bony sella turcica
+    - Sella turcica is partially filled with CSF
+          - Rarely completely empty
+          - Pituitary gland
+                  - Almost never completely absent
+                  - Thin, flattened rim of residual pituitary tissue
+                  - Generally at posteroinferior sellar floor
+    - Primary or secondary
+          - Primary empty sella
+                  - Common normal variant (15% of brain MRs), incidental finding
+                  - Normal or increased CSF pressure
+                  - Near-normal volume of compressed pituitary tissue
+                  - No history of trauma, surgery, radiation
+                  - Patients typically endocrinologically normal
+          - Secondary empty sella
+                  - Many etiologies
+                            - Surgery
+                            - Radiation
+                            - Bromocriptine therapy
+                            - Trauma
+                            - Sheehan syndrome (postpartum pituitary necrosis)
+                            - Pituitary apoplexy
+                            - Pituitary abscess
+
+# IMAGING
+
+- ## General Features
+  
+  
+    - ### Best diagnostic clue
+      
+      
+          - Intrasellar CSF with pituitary gland flattened against sellar floor
+          - Bony sella may be normal or large
+    - ### Location
+      
+      
+          - Intrasellar CSF
+    - ### Size
+      
+      
+          - Variable
+- ## Imaging Recommendations
+  
+  
+    - ### Best imaging tool
+      
+      
+          - Sagittal T1WI
+          - Coronal T2WI
+- ## CT Findings
+  
+  
+    - ### NECT
+      
+      
+          - CSF-like herniation of CSF into bony sella
+                  - Bony sella typically appears normal
+          - May also be moderately enlarged (secondary to pulsatile CSF)
+                  - Bony margins intact, not eroded/demineralized
+    - ### CECT
+      
+      
+          - Infundibular stalk and pituitary gland enhance normally
+          - Occasionally intrasellar CSF collection may be asymmetric
+                  - Stalk may appear tilted to one side
+- ## MR Findings
+  
+  
+    - ### T1WI
+      
+      
+          - Primary empty sella
+                  - Fluid looks exactly like CSF
+                  - Stalk usually midline
+                            - Gland + stalk = anchor sign on coronal imaging
+                            - Stalk may be tilted to one side if intrasellar CSF herniation is asymmetric
+                  - 3rd ventricle, hypothalamus usually normal
+                            - Rare: Herniation of optic chiasm, anterior 3rd ventricle into sella
+          - Secondary empty sella
+                  - Look for changes of transsphenoidal hypophysectomy
+                            - Defect in sellar floor
+                            - Fat packing
+                  - May cause distortion of stalk, chiasm
+                            - Stalk and pituitary remnant(s) may be scarred/adhesed to side or bottom of sella turcica
+    - ### T2WI
+      
+      
+          - Fluid exactly like CSF
+    - ### FLAIR
+      
+      
+          - Intrasellar fluid suppresses completely on FLAIR
+    - ### DWI
+      
+      
+          - No restriction
+    - ### T1WI C+
+      
+      
+          - Primary empty sella
+                  - Stalk, gland enhance normally
+                  - No other abnormalities
+          - Secondary empty sella
+                  - Gland and stalk may be adhesed/distorted
+
+# DIFFERENTIAL DIAGNOSIS
+
+- [Idiopathic Intracranial Hypertension](/document/idiopathic-intracranial-hypertensi-/d7a0a1b6-1d94-473c-9fe9-021443969f9f)
+    - Often not truly "idiopathic" (e.g., dural venous sinus stenosis)
+    - Usually obese female, 20-40 years
+    - Headache, papilledema
+    - Intraoptic protrusion of optic nerve head
+    - Enlarged optic nerve sheaths ± empty sella
+    - Ventricles may appear slit-like
+    - Subarachnoid spaces (cisterns, surface sulci) may be small
+- ## Secondary Intracranial Hypertension
+  
+  
+    - Increased intracranial pressure caused by
+          - Obstructive hydrocephalus (intra-/extraventricular)
+          - Mass (neoplasm, etc.)
+    - Dilated anterior recesses of 3rd ventricle herniate into sella
+    - Look for mass, evidence for transependymal CSF migration
+- [Arachnoid Cyst](/document/arachnoid-cyst/d25aaeb3-5b3c-4483-99dc-2757468eedb9)
+    - Suprasellar arachnoid cyst may herniate into bony sella
+          - Bony sella often enlarged, eroded/expanded
+    - Look for 3rd ventricle or optic chiasm displaced by CSF-containing mass
+    - Cyst walls may be visible on thin-section imaging
+- [Pituitary Apoplexy](/document/pituitary-apoplexy/43efc995-d33c-4ac1-be70-e3237eec9fc9)
+    - Acute: Pituitary gland usually enlarged, not small
+          - Usually hemorrhagic
+          - Look for rim enhancement around periphery of enlarged, nonenhancing gland
+    - Chronic: May cause empty sella
+- [Pituitary Anomalies](/document/pituitary-anomalies/09ca9b54-a3d9-43fd-a9cc-4c0212b578a1)
+    - Ectopic posterior pituitary "bright spot"
+          - May cause small pituitary gland
+          - Infundibular stalk short, "stubby"
+          - Bony sella often small, shallow appearing
+          - Sella can appear partially empty
+    - Persisting embryonal infundibular recess of 3rd ventricle
+          - Can mimic empty sella (rare)
+    - Pituitary stalk duplication
+          - Rare
+          - Look for 2 thin stalks
+          - Sella may appear partially empty
+- [Sheehan Syndrome](/document/pituitary-apoplexy/43efc995-d33c-4ac1-be70-e3237eec9fc9)
+    - Original clinical description
+          - Postpartum hemorrhage
+          - Pituitary necrosis
+          - Lactation failure
+          - Hypopituitarism
+    - Anterior pituitary necrosis
+          - Leaves small residual pituitary gland
+          - Result = empty sella
+    - May occur years after pregnancy
+    - Slow clinical progression over years suggests factors other than ischemia may be involved
+    - Necrosis may be caused by antihypothalamus, antipituitary antibodies
+    - Pituitary autoimmunity may perpetuate hypopituitarism
+- [Epidermoid Cyst](/document/epidermoid-cyst/704c5ddf-e1f7-4a5d-a1b8-5b0e603170d9)
+    - True intrasellar epidermoid cyst very rare
+          - Off midline > midline
+          - Usually extension from cerebellopontine angle epidermoid
+
+# PATHOLOGY
+
+- ## General Features
+  
+  
+    - ### Etiology
+      
+      
+          - Primary empty sella
+                  - Deficient diaphragma sellae
+                            - Dural covering of sella is incomplete (widened)
+                            - Leaves widened dural opening for infundibular stalk
+                            - Allows intrasellar herniation of arachnoid with CSF from suprasellar subarachnoid cistern above
+                            - Compresses pituitary gland against sellar floor
+                            - Traction on infundibular stalk may cause alteration in visual system
+                  - Pulsatile CSF may gradually enlarge sella
+          - Secondary empty sella
+                  - Common: Surgery, bromocriptine therapy, radiation
+                  - Less common: Pituitary apoplexy, pituitary abscess
+                  - Rare: Pituitary necrosis in viral hemorrhagic fever (e.g., hanta)
+- ## Gross Pathologic & Surgical Features
+  
+  
+    - Diaphragma sellae appears widened, gaping
+    - Intrasellar herniation of arachnoid-containing CSF
+
+# CLINICAL ISSUES
+
+- ## Presentation
+  
+  
+    - ### Most common signs/symptoms
+      
+      
+          - Incidental, usually asymptomatic
+          - Headache
+          - Visual disturbances 1-15%
+                  - Idiopathic intracranial hypertension (IIH)
+                  - Optic chiasm herniation into ES may cause visual symptoms
+          - Endocrine disturbances
+                  - 20% of adults have subtle laboratory abnormalities
+                  - Majority (70%) of children with ES have endocrine abnormalities
+- ## Demographics
+  
+  
+    - ### Age
+      
+      
+          - Peak incidence between 50-60 years
+          - Increased CSF pressure presents earlier (30-40 years)
+    - ### Sex
+      
+      
+          - F:M = 5:1
+    - ### Epidemiology
+      
+      
+          - 10-15% found incidentally on imaging
+- ## Natural History & Prognosis
+  
+  
+    - Both primary and secondary empty sella usually benign, do not require treatment
+    - If related to IIH, can result in vision loss or CSF leak
+    - Hormonal replacement therapy may be required in some cases
+    - Surgery (rare)
+          - "Chiasmapexy" to elevate optic chiasm if severe visual disturbances caused by inferior displacement of optic chiasm into empty sella
+          - CSF rhinorrhea may require surgical intervention
+
+# DIAGNOSTIC CHECKLIST
+
+- ## Consider
+  
+  
+    - Incidental, normal variant in older adults
+    - Additional findings of IIH in younger females (e.g., dilated optic nerve sheaths, papilledema, dural venous sinus narrowing)
+    - Look for endocrine abnormalities in children
+- ## Image Interpretation Pearls
+  
+  
+    - Intrasellar fluid follows CSF **exactly**on all sequences
+
+ 8bb93cd6-d836-4878-89c3-865ebc070aea