Neurosurgery notes/Functional/Craniofacial pain/Compressive vascular disorder/Vago-glossopharyngeal neuralgia (VGPN)

Vago-glossopharyngeal neuralgia (VGPN)

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Compressive vascular disorder

General

  • Aka: Glossopharyngeal neuralgia
    • Pain frequently affects not only the ninth sensory territory of the ninth CN but also the one tributary of the vagus nerve (tenth CN).

Definition

Diagnostic criteria

  1. Recurring paroxysmal attacks of unilateral pain in the distribution of the glossopharyngeal nerve and fulfilling criterion B
    1. Ear, base of the tongue, tonsillar fossa and/or beneath the angle of the jaw
  1. Pain has all of the following characteristics:
    1. Lasting from a few seconds to 2 minutes
    2. Severe intensity
    3. Electric shock-like, shooting, stabbing or sharp in quality
    4. Precipitated by swallowing, coughing, talking or yawning
  1. Not better accounted for by another ICHD-3 diagnosis.

Subclasses

  • Classical glossopharyngeal neuralgia
    • Glossopharyngeal neuralgia developing without apparent cause other than neurovascular compression.
  • Secondary glossopharyngeal neuralgia
    • Glossopharyngeal neuralgia caused by an underlying disease.
  • Idiopathic glossopharyngeal neuralgia
    • Glossopharyngeal neuralgia with no evidence either of neurovascular compression or of causative underlying disease.

Numbers

  • Incidence: 1/70 of trigeminal neuralgia.
  • 1% of facial pain syndromes
  • VGPN is one hundred times less frequent than TN.

Clinical

  • Severe, lancinating pain in the distribution of the glossopharyngeal and vagus nerves
    • Throat & base of tongue most commonly involved, radiates to ear (otalgia), occasionally to neck),
    • Occasionally with salivation and coughing.
  • Rarely (life threatening):
    • Hypotension,
    • Syncope
    • Cardiac arrest
    • Convulsions
  • May be triggered by
    • Swallowing
    • Talking
    • Chewing
  • Trigger zones are rare.
  • Can be associated with
    • Cardiovascular manifestations, especially syncopes
    • Digestive manifestations
      • Rare

Aetiology and pathophysiology

  • Primary VGPNs (classical VGPN)
    • CN9/10 arterial compression,
      • Predominantly but not always at REZ
      • PICA
      • AICA
      • Vertebral artery
  • Secondary VGPNs
    • Extracranial or intracranial tumours, or various other specific pathologies.

Investigation

  • ENT investigations and MRI rule out diagnoses of extracranial or intracranial tumours, vascular lesions, Chiari malformations, and others.
  • Clinical examination does not reveal any obvious neurological deficit.
  • Radiological
    • High- resolution MR
      • Depict compressive vessels with a high sensitivity and specificity
        • PICA
        • VBA
          • Both vessels lie ventral to the CN9/10 REZ
notion image

Diagnosis

  • Based on the particular features of the pain.

Treatment

Medical

  • Local anaesthetic to tonsillar pillars and fossa.
  • Anticonvulsants like TGN
  • If fail move on to Surgical tx

Stereotactic radiosurgery (SRS)

  • Recently attempted with some promising results

Surgical

  • Indication
    • Persistence and severe of pain
  • Methods
    • MVD: Intracranial approach:
      • 1st option for Classical VGPN
        • Retromastoid craniectomy
          • Posterior to the tip of the mastoid process and retrocondylian, so as to follow a laterotonsilar— infrafloccular trajectory, along the cerebellomedullary fissure.
            • Such a trajectory allows to avoid stretching of the eighth nerve and related complications
        • The covering arachnoid membranes that are frequently thickened and adhesive to the rootlets should be widely opened and excised.
    • Nerve division via extra- or intra-cranial approach (latter may be required for permanent relief).
      • Section of CN 9
        • Section of preganglionic glossopharyngeal nerve (IX) and upper one–third or two fibers (whichever is larger) of vagus (X).
        • Nerve identification
          • IX is readily identified at its dural exit zone where it is separated from X by a dural septum.
          • The upper third of X is usually composed of a single rootlet, or less commonly, multiple small rootlets.

Percutaneous RF- ThRh

  • Reserved to pain of neoplastic origin
  • Rarely indicated for primary VGPN, due to
    • High risk of creating deficits in the motor territories of the CN 9, 10
  • Performed at the foramen jugularis

Results

  • MVD
    • Achieved complete pain relief was achieved in 94.4% of the patients.
    • No mortality,
    • No general morbidity,
    • No wound complications.
    • Neurological deficits consisted of some degree of (permanent) dysphonia and dysphagia in two patients.
  • SRS
    • That might be promising needs more long- term evaluation
  • Initial post-op dysphagia usually resolves.
  • Cardiovascular complications following vagal section have been reported, warrants close monitoring 24 hrs.