Skull base syndromes

Skull base syndromes are caused by malignancies or inflammatory conditions that affect the base of the skull and the cranial nerves exiting the skull. The location of the pathology can often be determined by characteristic features produced by nerve damage and other localizing space-occupying effects (e.g., pain, proptosis). Syndromes primarily involving the cranial nerves are discussed in a separate article (see cranial nerve disorders).

• Etiology: sphenoid wing meningioma and rarely, trauma
• Clinical features ^[1]
  • Upper eyelid ptosis
  • Proptosis of the eye
  • Ophthalmoplegia
  • Dilated and fixed pupil
  • Loss of sensation of the upper eyelid and forehead due to damage to the trigeminal nerve ^[2]

• Etiology
  • Frontal lobe tumors, typically parasellar or subfrontal meningiomas
  • Olfactory groove meningioma; : meningiomas arising from the cribriform plate and frontosphenoidal suture (see meningiomas)
• Clinical features
  • Ipsilateral atrophy of the optic nerve
  • Contralateral papilledema
  • Anosmia

• Etiology: damage to the orbital fissure or the optic canal resulting from an inflammatory condition or space-occupying lesion
• Clinical features
  • Ophthalmoplegia
    • Due to damage to the cranial nerves passing through the orbital fissure
    • Partial/complete paresis of oculomotor nerve (CN III), trochlear nerve (CN IV), and abducens nerve (CN VI)
  • Blindness ^[3]
  • Loss of sensation to the upper face may occur (see “Cranial nerve disorders“). ^[4]

References:^[3][4]

• Etiology
  • Cavernous sinus thrombosis (e.g., due to sinusitis and contiguous spread of infection)
  • Carotid-cavernous fistula
  • Cavernous sinus tumors
  • Pituitary tumors producing mass effect
  • Carotid artery fistula or aneurysms
  • Tolosa-Hunt syndrome (idiopathic granulomatous inflammation of the cavernous sinus)
• Clinical features
  • Swelling of the conjunctiva
  • Proptosis
  • Signs of CN palsy due to compression (CN III, IV, V-1, V-2, and VI pass through the cavernous sinus)
    • Painful ophthalmoplegia: partial/complete paresis of oculomotor nerve (CN III), trochlear nerve (CN IV), and abducens nerve (CN VI)
    • Absent corneal reflex: paresis of the ophthalmic branch of the trigeminal nerve (V1)
    • Loss of upper facial and corneal sensation may occur due to damage to the trigeminal branches of V1 and V2 (see “Cranial nerve disorders“).
  • Horner syndrome

• Etiology: : most commonly vestibular schwannomas (acoustic neuroma), although other cerebellopontine angle tumors may result in the same presentation
• Clinical features
  • Unilateral hearing loss
  • Tinnitus
  • Vertigo
  • Headache
  • Loss of facial sensation

References:^[5]

• Etiology: complication of otitis media and mastoiditis that spreads to the petrous apex of the temporal bone, can also be tumor growth in the same area
• Clinical features: typical triad
  • Lateral rectus palsy
  • Retro-orbital pain
  • Otorrhea (ear discharge)
• Diagnostics: MRI to localize lesion, culture of middle ear effusion to determine pathogen
• Treatment: Broad spectrum IV antibiotics (eventually tailored to culture results); surgery for refractory or complicated cases despite medical therapy

• Etiology: inflammation or tumor growth at the base of the skull (e.g., nasopharyngeal cancer) which infiltrates the caudal cranial nerves (see “Pharyngeal cancer“)
• Clinical features: unilateral paresis of the trigeminal (sensory and motor), facial, vestibulocochlear, glossopharyngeal, vagus, accessory, and hypoglossal nerves (see “Cranial nerve disorders“)