To the Editor:—

We recently encountered a case of idiopathic trigeminal neuralgia associated with atypical facial pain that reinforces the importance of cranial imaging in evaluating selected patients with such symptoms.

A 58-yr-old woman, 157 cm tall, weighing 55 kg, without any significant medical history, had a long history (since 1988) of pain in the right upper jaw that was triggered by face washing and made feeding difficult. This was diagnosed as idiopathic second-division trigeminal neuralgia. Two hundred milligrams of carbamazepine controlled the pain well, and no other treatment was used.

At the end of 1994, acute pain that was no longer alleviated by carbamazepine appeared and rapidly worsened. This brought her to our hospital emergency clinic. She complained of a continuing pain in the distribution of the right trigeminal nerve (branches 1 and 2). There also was a pressure point on her right cheek that responded to very light stimulus. Her skin showed a very slight hypoesthesia. Later, she complained of headache and a swelling sensation on the right side of her face. A plain skull radiograph showed a deformed sella turcica. Computed tomography and magnetic resonance imaging examinations revealed a markedly enlarged third ventricle, consistent with hydrocephalus. No other abnormalities were discovered. A week later, she started having difficulty walking, disorientation, and markedly decreased memory and was admitted to our hospital. Her cerebrospinal pressure was normal (16.1 mmHg), but a diagnosis of normal pressure hydrocephalus resulted in the performance of a ventricular penetrial shunt. After the operation, the acute facial pain disappeared quickly, returning to the original level of trigeminal neuralgic pain. With 200 mg of daily carbamazepine intake, she has conducted daily life without any difficulty.

On further questioning, her family recalled incidents that suggested a decreased short-term memory starting about a year before the current hospital admission. It is possible that hydrocephalus was also responsible for some of her persistent pain because there have been sporadic cases of facial pain associated with hydrocephalus. 1–3Had brain-imaging examinations been performed for this patient before, the development of hydrocephalus could have been detected, and this might have prevented the exacerbation of the pain.

Maurice-Williams RS, Pilling J: Trigeminal sensory symptoms associated with hydrocephalus. J Neurol Neurosurg Psychiatry 1977; 40: 641–4
Findler G, Feinsod M: Reversible facial pain due to hydrocephalus with trigeminal somatosensory evoked response changes. J Neurosurg 1982; 57: 267–9
Arienta C, Farabola S-M: Facial pain associated with hydrocephalus by aqueduct stenosis. J Neurosurg Sci 1986; 30: 81–2