46TH
ANNUAL
CONGRESS
OF
THE
SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
99
Peterson block:
The needle is inserted caudal to the angle formed by the bony orbit of the eye and
the dorsal margin of the zygomatic arch. The needle is advanced in a caudomedial
direction until the periorbita is infiltrated which will result in the characteristic loss
of resistance as the bevel advances through the periorbital fascia. There may be
movement of the globe of the eye at this point. Aspiration is performed prior to
administration of the local anaesthetic.
Complications:
The retrobulbar block can cause trauma to the optic nerve, loss of motor function of
the muscles of the eye (recti, obliques and retractor bulbi muscles) and haematoma
formation due to penetration of large ophthalmic vein and artery. The modified
retrobulbar block may seed infection and neoplasia from the conjunctiva into the
periorbita. The modified retrobulbar technique has the potential to cause damage to
the brain via advancement of the needle through the optic canal.
Efficacy:
In cadaver study performed in bovines the two techniques were compared for
accuracy of placement within the periorbita and associated structures. The modified
retrobulbar technique placed local anaesthetic within the periorbita with 100%
percent accuracy but also placed local anaesthetic at the optic chiasma in 40% of
cases. The Peterson block had an accuracy of 40% in placement of local anaesthetic
within the periorbita.
Maxillary Nerve Block:
Indications:
Dental procedures involving the maxillary cheek teeth, maxillary incisors, maxillary
lips and associated soft tissues of the maxilla.
Anatomy:
The maxillary nerve provides sensory innervations to all structures and soft tissue of
the maxilla including the soft and hard palate. The nerve is a branch of the trigeminal
nerve that exits the neurocranium through the foramen rotundum and passes
through the pterygoplatine fossa before giving off the zygomatic, pterygopalatine
major and minor ne rves before continuing through the maxillary foramen into the
infraorbital canal where it exits rostrally from the viscerocranium through the
infraorbital foramen as the infraorbital nerve.
99