Head and Neck Imaging

Perineural tumour spread, head and neck

tumoral dissemination from the primary tumour site along nerve branches. Such tumour spread usually occurs along the nerve sheath, not within the nerve itself. Perineural tumour spread occurs in all head and neck malignancies; adenoid cystic carcinoma is notorious for its tendency to spread along nerves. Perineural tumour spread is associated with a decreased survival rate. Symptoms include pain, paresthesias and muscle weakness and atrophy, but about 40% of patients do not show particular symptoms. Imaging diagnosis is important to avoid tumour 'recurrence' from unrecognized perineural spread; however, microscopic perineural tumour spread cannot be recognized by CT and MRI. Perineural tumour spread occurs most frequently along the branches or main trunk of the maxillary nerve, mandibular nerve and facial nerve.

Imaging findings in perineural tumour spread include:

  • thickening and/or enhancement of one or more nerve branches (Fig.1).

  • (often small) tumoral lesions at some distance from the primary site, in a neural 'crossroad' such as the pterygopalatine fossa or Meckel's cave (Fig. 1).

  • widening, destruction or enhancement of a skull base neural foramen or canal (e.g. foramen ovale, vidian canal).

  • denervation atrophy of muscles supplied by the affected nerve (denervation muscle atrophy, head and neck (VI:2), Fig. 1; parotid gland (VI:2), Fig. 3))

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    Fig.1

    Patient complaining of pain in the area of the right maxillary nerve. Clinical examination showed a small intraoral nodule, on the right side of the hard palate; biopsy revealed adenoid cystic carcinoma. Gadolinium-enhanced T1-weighted spin-echo images are shown (a and b: axial, c and d: coronal). Abnormal contrast enhancement is seen in the greater palatine canal (containing branch from maxillary nerve for palatal region) (a and c: arrow). The abnormal enhancement in the pterygopalatine fossa and foramen rotundum (b and d: arrow), as well as in the vidian canal (b and d: arrowhead), is further evidence of retrograde perineural tumour spread (courtesy by Roberto Maroldi, MD, Brescia, Italy).
    Perineural tumour spread, head and neck, Fig.1 (a)
    Perineural tumour spread, head and neck, Fig.1 (b)
    Perineural tumour spread, head and neck, Fig.1 (c)
    Perineural tumour spread, head and neck, Fig.1 (d)