2024 Volume 66 Issue 1 Pages 85-87
Abstract: Various neuropathies of the cranil nerves can accompany trigeminal neuropathic pain attributed to space-occupying lesions. In this case report, the patient presented with persistent intraoral pain and numbness on the right side of the face. Cranial nerve examination revealed dysfunctional eye movements, diplopia, and mechanical hyposensitivity in the mandibular region. The patient was diagnosed with neuropathy due to intracranial lesions and referred to the Department of Neurosurgery and Otorhinolaryngology. The patient was suspected of having malignant lymphoma and is currently undergoing neurosurgical intervention. This article discusses the importance of the examination of the cranial nerve for patients with persistent pain in the trigeminal nerve distribution.
A space-occupying lesion presenting with persistent pain in the trigeminal region, hyperalgesia, allodynia, hypoesthesia, and/or hypoalgesia, is classified as ‘trigeminal neuropathic pain attributed to other disorder (4.1.2.4)’ by the International Classification of Orofacial Pain (ICOP) [1]. Space-occupying lesions are mostly neoplastic and require an early diagnosis to allow the ideal treatments. However, early symptoms are often similar to trigeminal neuralgia or toothache, complicating diagnosis. Magnetic resonance imaging (MRI) is necessary for differentiation. However, if the trigeminal neuralgia or toothache diagnosis is made at the first visit, prompt MRI may not be performed or drug therapy may be initiated. As a result, correct diagnosis is often delayed.
There are few reports of cranial nerve examination leading to trigeminal neuropathic pain due to space-occupying lesions [2,3]. This report is a case of trigeminal neuropathic pain caused by a space-occupying lesion successfully identified with a cranial nerve examination.
The authors certify that they have obtained appropriate patient consent forms in which the patient has authorised sharing her images and other clinical information, but not her name or initials, in a journal.
A 71-year-old woman presented with a chief complaint of persistent pain in the right orofacial region and dysesthesia and numbness of the gingiva and tongue. The chief complaint started 6 months prior when the patient suddenly became aware of persistent pain and numbness on the right side of the face. The pain worsened over time and spread from the right cheek to the oral cavity, then to the right side of her face from the frontal region to the mandibular jaw. Additionally, she experienced severe paroxysmal pain in the oral region while eating and had double vision. She consulted with a neurosurgeon and underwent MRI without contrast for possible trigeminal neuralgia, but a causative disease could not be identified. Carbamazepine was prescribed for the diagnostic treatment of idiopathic trigeminal neuralgia, but her symptoms remained unchanged.
A temporomandibular joint examination revealed an active range of motion of <30 mm, and the mandible deviated to the right while opening. Somatosensory testing results were positive (dysesthesia) and negative (hypoalgesia) in the face (all three branches of the trigeminal nerve [CN V1-3]) and positive (dysesthesia) in the oral region. Quantitative sensory testing (QST) revealed a mechanical detection threshold (MDT) of 2.0 g on the affected side (CN Ⅴ2) and 0.008 g on the unaffected side (CN V2). The cranial nerve examination also revealed diplopia and difficulty in ocular abduction; neurological dysfunction of cranial nerve V1 was considered based on the range of symptoms (Fig. 1).
In brief, to test lateral and vertical gaze, the patient is asked to follow the examiner’s finger as it moves horizontally and then vertically. While performing these tests, it is essential that the target is not too close to the patient and does not move too fast. Moreover, the patient should not be allowed to move his or her head. Both eyes should move smoothly through the full range in parallel with each other with no signs of nystagmus (involuntary horizontal, rotary, or vertical movements of the eye) or complaints of diplopia.
The patient complained that the operator’s index finger appeared to be double. Right abducens nerve palsy was present on the cranial nerve examination.
The patient underwent a second MRI, this time with contrast, which revealed a heterogeneous, intensely enhanced mass measuring 26 × 13 mm around the coronoid process of the mandible, extending to the right temporal muscle (Fig. 2A-C). This mass was not clearly shown on the original non-contrast-enhanced MRI (Fig. 2D). A mass occupied an area from the right Meckel’s space along CN V2 to the foramen ovale, fossa pterygopalatine, near the superior nasal meatus and nasal duct, and along CN V3 to the foramen ovale and dorsal side of the lateral pterygoid muscle. The radiological diagnosis was ‘possible malignant lymphoma’.
The patient was referred for neurosurgery, otorhinolaryngology, and chemotherapy.
T1-weighted, contrast-enhanced axial (A, B) and coronal (C) images depicting extensive infiltration of the right Meckel’s space with extension to the foramen ovale and fossa pterygopalatine, near the superior nasal meatus and nasal duct. Thickening and contrast enhancement of the right trigeminal nerve was also apparent (yellow arrows). Mass was not well detected on the original non-contrast-enhanced axial MRI (D).
Trigeminal neuropathic pain is a condition characterized by painful paroxysms associated with neurologic deficits in the trigeminal divisions and represents a secondary disorder that affects the trigeminal nerve (accounting for 15% of trigeminal neuralgias) [4].
Neuropathies comprise a group of varied conditions which are precipitated by neural injury or disease. These conditions can result in negative symptoms (non-painful neuropathy such as numbness, hypoesthesia, and/or hypoalgesia, and decreased sensitivity to stimulation), or positive symptoms (painful neuropathy such as hyperalgesia, allodynia). Hyperalgesia is increased pain from an already painful stimulus. Allodynia is pain from an innocuous stimulus. Hypoesthesia is decreased sensation, and hypoalgesia is decreased pain from a normally-painful stimulus.
Kalladka et al. [5] reported that nerve injury due to advanced malignant processes is characterized by significantly elevated heat and electrical thresholds (hyposensitivity). Inflammatory processes were accompanied by reduced electrical detection thresholds (hypersensitivity). Consistent with these findings, this case’s QST results had an elevated mechanical detection threshold.
In addition to this case, six other cases of abducens nerve palsy and trigeminal neuropathy due to malignant lymphoma have been reported (Table 1). A previously reported review of sixth nerve palsy revealed an age range of 44-71 years, with 3 males and 3 females; the site of onset was 3 on the right side, 2 on the left side, and one case on both sides. Trigeminal disturbance included one case of anterior forehead pain, one case of trigeminal palsy, one case of numbness and pain in the buccal region, one case of pain in front of the left auricle and hyperalgesia of the left face, and one case of sensory disturbance. Regarding imaging modalities, one case was diagnosed with X-ray scanning of the head and chest, computed tomography (CT), and MRI; one with MRI; one with MRI and magnetic resonance angiography; one with CT, MRI, and fluorodeoxyglucose-positron emission tomography (FDG-PET); and one case with MRI and FDG-PET. Regarding the site of the lesion, the cavernous sinus and middle cranial fossa were the locations of one case, the cavernous sinus for another, and the cerebellopontine angle for another. For two of the cases, the site was considered as not described. Chemotherapy was administered, and surgical treatment was not performed in any of the cases. In this case, carbamazepine was prescribed for the diagnostic treatment of idiopathic trigeminal neuralgia and was initially ineffective. The patient is currently undergoing chemotherapy for malignant lymphoma at a hospital.
This very rare condition with stabbing facial pain from central nervodata system lymphoma involving Meckel’s cave near the wing of the sphenoid at the base of the skull mimicked other more common diseases clinically and radiographically. It presents challenges in the diagnosis of lymphomas that appear in atypical locations. Clinically, the paroxysmal pain in the unilateral V3 distribution in this patient appeared to be trigeminal neuralgia which, in most patients, involves the trigeminal nerve root at the entrance to the pons due to an abnormal loop of the vasculature caused by local compression and demyelination [6], and is associated with tumours in approximately 10% of patients [7]. Other reports of malignant lymphoma originating from the wing of the sphenoid, Meckel’s cave, are incredibly rare and have only been reported in three other patients [8]. Previously reported skull base lesions are often misdiagnosed as meningiomas or schwannomas, as was the case in this patient. Furthermore, previous reports of primary malignant lymphoma in Meckel’s cave have only described symptoms resembling trigeminal neuralgia [4,9,10].
The general practitioner may find it challenging to provide a correct diagnosis of trigeminal neuropathic pain. Therefore, the authors propose here a diagnostic algorithm for trigeminal neuropathic pain due to a space-occupying lesion (Fig. 3). In this case, Cranial nerve V examination showed trigeminal nerve deficits with both positive (allodynia and dysesthesia on the right side of the face) and negative (hypoesthesia) symptoms. In the cavernous sinus, the VI cranial nerve is located lateral to the internal carotid artery, medial to and close to the second branch (the Ⅴ cranial nerve). Furthermore, the patient was unable to abduct on the right side. The lateral rectus muscle, which controls the abduction of the eyeball, is innervated by the VI cranial nerve. Thus, the patient’s right lateral rectus muscle, or right abducens nerve, was involved.
In the presence of trigeminal neuropathy and progressive sixth cranial nerve palsy, prompt contrast-enhanced MRI is required to identify the underlying etiology, as demonstrated by this malignant condition.
Although MRI is the best method for identifying disorders that cause secondary trigeminal neuralgia, other methods include neurophysiological tests, such as trigeminal reflexes and trigeminal evoked potentials. Cranial nerve examination is a simple diagnostic test that does not require special medical equipment and can be performed by general practitioners. Dentists are expected to perform this examination, understand the underlying neuroanatomy and the implications of abnormal findings, and refer patients appropriately.
| Author | Journal | Patient Age/ Gender |
Side | Trigeminal nerve symptoms | Imaging modality | Site of lesion | Treatment | Outcome |
|---|---|---|---|---|---|---|---|---|
| Nogaki | No To Shinkei 1989; 41: 259-262 | 67 / m | left | anterior forehead pain | X-ray scans of the head and chest, CT, MRI | cavernous sinus and middle cranial fossa | chemotherapy | nd |
| Lee | J Clin Neuroophthalmol 1992; 12: 203-206 | 44 / f | left | palsy | MRI | cavernous sinus | chemotherapy | all extraocular movements recovered |
| Hirose | Rinsho Shinkeigaku 2016; 56: 48-50 | 62 / m | right | numbness and pain in the buccal region | MRI, MRA | nd | chemotherapy | improved |
| Asanome | Rinsho Shinkeigaku 2018; 58: 93-99 | 58 / f | both (right: Ⅵ, left: Ⅴ) |
pain in front of the left auricle and hyperalgesia of the left face | CT, MRI, FDG-PET | nd | chemotherapy | died after 2.5 years |
| Mori | Cureus 2019; 11: e5675 | 50 / m | right | sensory disturbance | MRI, FDG-PET | cerebellopontine angle | chemotherapy | mitigated |
| Present case | 71 / f | right | persistent intraoral pain and numbness on the right side of the face | Contrast-enhanced MRI | right Meckel’s space | chemotherapy | under treatment |
m, male patients; f, female patients; CT, computed tomography; MRI, magnetic resonance imaging; MRA, magnetic resonance angiography; FDG-PET, positron emission tomography; Contrast-enhanced MRI, dynamic contrast-enhanced magnetic resonance imaging; nd, not described
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