Pain in ischaemic ocular motor cranial nerve palsies

Pain is a common feature of microvascular ischaemic ocular motor cranial nerve palsies (MP). The natural history of pain in this condition has not been studied. The purpose of this report is to define the spectrum of pain in isolated MP, with special reference to diabetic versus non-diabetic patients.

Retrospective and prospective chart review was performed on 87 patients with acute-onset MP of a single cranial nerve (CN III, oculomotor; CN IV, trochlear; CN VI, abducens) that progressively improved or resolved over 6 months.

Five of the 87 patients had two events, making the total number events 92. There were 39 (42.4%) CN III palsies, five (5.4%) CN IV palsies and 48 (52.2%) CN VI palsies. Thirty-six (41%) patients had diabetes. Pain was present in 57 (62%) events. The majority of diabetic and non-diabetic patients had pain. Pain preceded diplopia by 5.8 (SD 5.5) days in one-third of events. There was a trend towards greater pain with CN III palsies, but this was not statistically significant. Patients who experienced severe pain tended to have pain for a longer duration (26.4 (SD 21.7) days compared with 10.8 (SD 8.3) and 9.5 (SD 9) days for mild and moderate pain, respectively). There was no correlation between having diabetes and experiencing pain.

The majority of MP are painful, regardless of the presence or absence of diabetes. Pain may occur prior to or concurrent with the onset of diplopia. Non-diabetic and diabetic patients presented with similar pain characteristics, contrary to the belief that diabetic patients have more pain associated with MP.