Add causal model for Semicircular Canal Dehiscence Syndrome

kb/disorders/Semicircular_Canal_Dehiscence_Syndrome.yaml

@@ -1,6 +1,4 @@
 name: Semicircular Canal Dehiscence Syndrome
-creation_date: '2026-01-08T22:33:12Z'
-updated_date: '2026-01-08T22:33:12Z'
 category: Structural
 disease_term:
   preferred_term: semicircular canal dehiscence syndrome
@@ -42,6 +40,10 @@ pathophysiology:
     explanation: >-
       Histopathological examination confirmed the anatomical basis of the dehiscence
       with direct dura-to-membranous duct contact at the bony defect.
+  downstream:
+  - target: Third Window Effect
+    description: >-
+      The bony defect creates a pathological third mobile window in the inner ear labyrinth.
 - name: Third Window Effect
   description: >-
     The dehiscence acts as a third mobile window that shunts acoustic energy away from
@@ -77,6 +79,27 @@ pathophysiology:
     explanation: >-
       This landmark paper establishes the third window mechanism as the cause of
       the conductive hearing loss pattern seen in SCDS.
+  downstream:
+  - target: Abnormal Sound and Pressure Transmission
+    description: >-
+      The low-impedance third window allows sound and pressure energy to aberrantly
+      stimulate vestibular end-organs.
+  - target: Conductive Hearing Loss
+    description: >-
+      Acoustic energy is shunted away from the cochlea through the dehiscence,
+      worsening air conduction while enhancing bone conduction.
+  - target: Autophony
+    description: >-
+      Enhanced bone conduction through the third window amplifies perception of
+      body-generated sounds including voice, breathing, and heartbeat.
+  - target: Hyperacusis
+    description: >-
+      Increased sensitivity to bone-conducted sounds due to the low-impedance
+      third window pathway.
+  - target: Pulsatile Tinnitus
+    description: >-
+      Intracranial vascular pulsations are transmitted to the cochlea via the
+      third window.
 - name: Abnormal Sound and Pressure Transmission
   description: >-
     Sounds and pressure changes that normally would not affect the vestibular system
@@ -108,6 +131,19 @@ pathophysiology:
     explanation: >-
       Clinical data from the original case series demonstrates the high frequency
       of sound- and pressure-induced symptoms in SCDS patients.
+  downstream:
+  - target: Vertigo
+    description: >-
+      Sound and pressure inappropriately deflect the cupula of the superior
+      semicircular canal, triggering vestibular responses.
+  - target: Sound-Induced Nystagmus
+    description: >-
+      Vestibular stimulation by loud sounds drives the vestibulo-ocular reflex,
+      producing nystagmus (Tullio phenomenon).
+  - target: Chronic Disequilibrium
+    description: >-
+      Persistent low-level vestibular stimulation from ambient sound and pressure
+      fluctuations causes ongoing imbalance.
 - name: Otic Capsule Bone Biology
   description: >-
     The otic capsule exhibits unique bone physiology with greatly suppressed remodeling.
@@ -135,6 +171,11 @@ pathophysiology:
     explanation: >-
       Histopathological examination showed absence of active bone resorption,
       supporting developmental thin-bone predisposition rather than active resorption.
+  downstream:
+  - target: Bony Dehiscence of Semicircular Canal
+    description: >-
+      Congenitally thin or underdeveloped otic capsule bone provides the structural
+      substrate for subsequent dehiscence formation.
 phenotypes:
 - category: Vestibular
   name: Vertigo
@@ -157,6 +198,10 @@ phenotypes:
     explanation: >-
       The original clinical series demonstrates that the vast majority of SCDS
       patients experience sound- or pressure-induced vestibular symptoms.
+  sequelae:
+  - target: Chronic Disequilibrium
+    description: >-
+      Recurrent vertigo episodes contribute to persistent sensation of imbalance.
 - category: Vestibular
   name: Sound-Induced Nystagmus
   frequency: VERY_FREQUENT
@@ -177,6 +222,11 @@ phenotypes:
     explanation: >-
       The biomechanics review confirms that sound-evoked nystagmus (Tullio phenomenon)
       is a characteristic feature of third window syndrome.
+  sequelae:
+  - target: Oscillopsia
+    description: >-
+      Involuntary eye movements driven by vestibular stimulation cause perception
+      of visual oscillation.
 - category: Vestibular
   name: Oscillopsia
   frequency: FREQUENT