Isolated trigeminal sensory neuropathy

Dear Editor,

We highlight the importance of clinical history and complementary examinations that are necessary in diagnosing infrequent pain syndromes. We describe a 58-year-old woman who presented with a 4-day history of pain on the right side of the facial and tongue hypoesthesia that was accompanied by dysesthesias.

Brain magnetic resonance imaging (MRI) scan showed the presence of lesions with contrast enhancement, compromising the topography of the right trigeminal nucleus and the left trigeminal nerve at the level of its emergence [Figure 1]. The rest of the neurological examination was normal. After treatment with methylprednisolone IV for 3 days, the condition of the patient evidently improved.

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Figure 1:

(a and b) Brain MRI with the presence of T2 hyperintense lesion with ring enhancement in the topography of the transition between the bridge and the right middle cerebellar peduncle and signs of increased signal intensity with thickening and enhancement by means of contrast of the left trigeminal nerve and at the level of its path at the level of the transition between the bridge and the left middle cerebellar peduncle.

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Trigeminal sensory neuropathy (TSN) is characterized by numbness on the skin or mucosal membranes in the distribution of the trigeminal nerves or weakness in the muscles of mastication. This condition has received attention in only a few case reports and main studies.^[1]

A spectrum of pathophysiological processes may affect the trigeminal nerves, including traumatic, vascular, demyelinating, infectious, neoplastic, and inflammatory disorders. This is similar to our patient who appeared to have a probable condition of lupus erythematosus after a thorough investigation.

Lecky and colleagues reported patients with idiopathic sensory disturbances restricted to the trigeminal territory and referred to this condition as “idiopathic TSN.”^[2]

Recent onset of bilateral trigeminal sensory hypoesthesia may subsequently follow one of the two clinical courses: In some patients, the disease will remain isolated to TSN, while in others, it will progress to facial onset sensory and TSN.^[3]

MRI is a valid method to investigate TSN, although its sensitivity and specificity seem variable, resulting in false positives and false negatives.^[4] Therefore, the relationship between the neuroradiological findings and the clinical picture is important and must be individualized to each patient.

Neuroimaging is useful in the diagnostic workup of TSN. Ruling out other causes of pain, such as space-occupying lesions, is important and requires an approach that is more specific than simply empiric medications.^[5]