Tomoyuki Shimpo

Trigeminal neuralgia in pontine cavernous angioma

Received: 19 April 1999Received in revised form: 3 August 1999Accepted: 15 August 1999

Sirs: Trigeminal neuralgia is gener-ally caused extra-axially by slightdamage to the entry zone of thetrigeminal nerve by tortuous vessels,aneurysms, arteriovenous malforma-tions, and tumors. It may also becaused by involvement of the intra-axial trigeminal nerve root in variouslesions, notably in multiple sclerosis.Cerebrovascular disease has not gen-erally been considered a cause oftrigeminal neuralgia, but two casesreports have recently been reportedof trigeminal neuralgia due to pon-tine infarction [1, 2]. We presenthere a case of trigeminal neuralgiadue to a cavernous angioma in thepons. Cavernous angioma in uppercervical spinal cord associated withtrigeminal neuralgia has also beenreported [3].

A 67-year-old man with a historyof diabetes mellitus noted severepain in his right upper eyelid 2weeks before admission to hospital.He had no history of hypertension.The pain lasted for only 2–3 s andoccurred about ten times a day. Nospecific actions provoked the pain.Neurological examination showedvery slight anisocoria (right pupillarger than left) and was otherwisenormal, including facial and cornealsensations and corneal reflex. Thepain was alleviated by 100 mg carba-mazepine per day. A few weeks laterhe noticed numbness over the righthalf of his face. Slightly decreasedpain and cold sensation were notedin the right face by neurological ex-amination 3 months after the onset.The blink reflex elicited by electricalstimulation of the supraorbital nerverevealed a prolonged R1 latency

(14.0 ms) after right-side stimulationand a normal R1 latency (10.8 ms)after left-side stimulation (upper nor-mal limit: 13.0 ms). The pain attacksincreased in frequency but were wellcontrolled by increasing the carba-mazepine the dose to 300 mg perday. T2-weighted magnetic reso-nance imaging 2 months after theemergence of symptoms disclosed alesion suggesting hemorrhage due tocavernous angioma located from theright lateral part of the pons to theright cerebellar hemisphere (Fig.1).Magnetic resonance imaging showedthat this lesion had become smaller 3 months later.

The brief, sharp, and recurrent na-ture of this patient’s pain was identi-cal to that of idiopathic trigeminalneuralgia. Its prompt relief after ad-ministration of carbamazepine is alsocommon. An association with idio-pathic trigeminal neuralgia is possi-ble, but the pain in this patientshould be regarded as secondary topontine cavernous angioma becausethe lesion was located at the intra-ax-ial root of the trigeminal nerve.

Several case studies have been re-ported of pontine cerebrovasculardisease presenting trigeminal neural-

gia [1, 2] or trigeminal neuropathy[4–6] as the sole or main symptom.In cases of trigeminal neuralgia, in-cluding the present case, facial hy-pesthesia is slight and the corneal re-flex is well preserved, whereas incases of trigeminal neuropathy, facialhypesthesia is prominent, and thecorneal reflex is often decreased orabsent. Therefore the trigeminal neu-ralgia in pontine stroke may resultwhen damage to the intra-axialtrigeminal nerve is slight. Unlike theidiopathic type, trigeminal neuralgiasecondary to pontine stroke is char-acterized by the presence of slightbut definite facial sensory distur-bance. Pain in the region of the firstbranch of the trigeminal nerve ob-served in two of the three reportedcases including the present case maybe another feature of the intra-axialtype, since the second or thirdbranch is typically affected in the idiopathic condition.

References

1.Balestrino M, Leandri M (1997)Trigeminal neuralgia in pontine isch-aemia. J Neurol Neurosurg Psychiatry62:297–298

2.Kim JS, Kang JH, Lee MC (1998)Trigeminal neuralgia after pontine in-farction. Neurology 51:1511–1512

3.Saito N, Yamakawa K, Sasaki T, SaitoI, Takakura K (1989) Intramedullarycavernous angioma with trigeminal neu-ralgia: A case report and review of theliterature. Neurosurgery 25:97–101

4.Berlit P (1989) Trigeminal neuropathyin pontine hemorrhage. Eur Neurol29:169–170

5.Komiyama M, Fu Y, Yagura H, YasuiT, Khosla VK (1993) Pontine hemor-rhages presenting as trigeminal neuropa-thy – report of three cases. Neurol MedChir (Tokyo) 33:234–237

6.Veerapen R (1989) Spontaneous lateralpontine hemorrhage with associatedtrigeminal nerve root hematoma. Neuro-surgery 25:451–453

T. ShimpoDepertment of Neurology, International Medical Center of Japan, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, JapanTel.: +81-3-32027181 Fax: +81-3-32071038

LETTER TO THE EDITORSJ Neurol (2000) 247 :139© Steinkopff Verlag 2000

Fig.1 T2-weighted MRI shows a mixedhigh- and low-intensity lesion surroundedby a low intensity rim in the right lateralpart of the pons, corresponding to the in-tra-axial trigeminal nerve root