Central trigeminal involvement in multiple sclerosis using high-resolution MRI at 3 T

Central vein sign and trigeminal lesions of multiple sclerosis visualised by 7T MRI

BACKGROUND

Although trigeminal nerve involvement is a characteristic of multiple sclerosis (MS), its prevalence across studies varies greatly due to MRI resolution and cohort selection bias. The mechanism behind the site specificity of trigeminal nerve injury is still unclear. We aim to determine the prevalence of trigeminal nerve involvement in patients with MS in a consecutive 7T brain MRI cohort.

METHODS

This observational cohort originates from an ongoing China National Registry of Neuro-Inflammatory Diseases. Inclusion criteria were the following: age 18 years or older, diagnosis of MS according to the 2017 McDonald criteria and no clinical relapse within the preceding 3 months. Each participant underwent 7T MAGNETOM Terra scanner (Siemens, Erlangen, Germany), using a 32-channel phased array coil at Beijing Tiantan Hospital. T1-weighted magnetisation-prepared rapid acquisition gradient echoes, fluid-attenuated inversion recovery (FLAIR) and fluid and white matter suppression images were used to identify lesions. FLAIR* and T2* weighted images were used to identify central vein sign (CVS) within the trigeminal lesions.

RESULTS

120 patients underwent 7T MRI scans between December 2021 and May 2023. 19/120 (15.8%) patients had a total of 45 trigeminal lesions, of which 11/19 (57.9%) were bilateral. The linear lesions extended along the trigeminal nerve, from the root entry zone (REZ) (57.8%, 26/45) to the pontine-medullary nucleus (42.2%, 19/45). 26.9% (7/26) of the lesions in REZ showed a typical central venous sign.

CONCLUSION

In this 7T MRI cohort, the prevalence of trigeminal nerve involvement was 15.8%. Characteristic CVS was detected in 26.9% of lesions in REZ. This suggests an inflammatory demyelination mechanism of trigeminal nerve involvement in MS.

Trigeminal neuralgia in multiple sclerosis: Association with demyelination and progression

BACKGROUND

Trigeminal neuralgia (TN) is a well-recognized symptom of multiple sclerosis (MS), yet its clinical characteristics related to MS subtype is poorly studied. Our aim was to evaluate whether development and clinical outcome of TN are influenced by MS phenotype.

METHODS

In this retrospective cohort study, our database from 2007 to 2022 was reviewed to identify patients who had both the diagnosis of MS and TN, whether TN was an initial symptom of MS or developed later in diagnosis. A detailed medical history and treatment outcome was obtained. Pain status was assessed retrospectively using the Barrow Neurological Institute Pain Scale (BNI-PS), with BNI-PS I-III considered as good pain control and BNI-PS IV-V as poor pain control.

RESULTS

58 patients had MS-related TN. 44 patients had relapsing remitting multiple sclerosis (RRMS) at the time of TN diagnosis, 11 had secondary progressive multiple sclerosis (SPMS) at the time of TN diagnosis, and type of MS was not clear in 3 patients at the time of TN diagnosis (either RRMS or SPMS). Over a mean follow up of 18.8 (SD=10.9) years, 30 transitioned to SPMS. TN was refractory to medical management in 9 RRMS and 22 SPMS patients (p = 0.001). TN patients with RRMS required lower median number of pain medications compared to SPMS (p = 0.014). Brain MRI was available in 41 of the entire cohort. Of these, 27 patients had demyelinating lesions in the trigeminal sensory pathway and 14 did not. Patients with existing lesions had a higher chance of failure of medical management (74% versus 36%, p = 0.017) and required surgical intervention (55% versus 7%, p = 0.003).

DISCUSSION

TN was not seen in primary progressive multiple sclerosis (PPMS). In patients who transitioned to SPMS, TN was more likely to be refractory to medical management. TN was more refractory in the presence of demyelinating plaque involving trigeminal sensory pathway.

Genetics behind Cerebral Disease with Ocular Comorbidity: Finding Parallels between the Brain and Eye Molecular Pathology

Cerebral visual impairments (CVIs) is an umbrella term that categorizes miscellaneous visual defects with parallel genetic brain disorders. While the manifestations of CVIs are diverse and ambiguous, molecular diagnostics stand out as a powerful approach for understanding pathomechanisms in CVIs. Nevertheless, the characterization of CVI disease cohorts has been fragmented and lacks integration. By revisiting the genome-wide and phenome-wide association studies (GWAS and PheWAS), we clustered a handful of renowned CVIs into five ontology groups, namely ciliopathies (Joubert syndrome, Bardet–Biedl syndrome, Alstrom syndrome), demyelination diseases (multiple sclerosis, Alexander disease, Pelizaeus–Merzbacher disease), transcriptional deregulation diseases (Mowat–Wilson disease, Pitt–Hopkins disease, Rett syndrome, Cockayne syndrome, X-linked alpha-thalassaemia mental retardation), compromised peroxisome disorders (Zellweger spectrum disorder, Refsum disease), and channelopathies (neuromyelitis optica spectrum disorder), and reviewed several mutation hotspots currently found to be associated with the CVIs. Moreover, we discussed the common manifestations in the brain and the eye, and collated animal study findings to discuss plausible gene editing strategies for future CVI correction.

Imaging of Trigeminal Neuralgia and Other Facial Pain

We review and illustrate the radiology of facial pain, emphasizing trigeminal neuralgia, relevant anatomy, current classification, concepts about etiology, and the role of imaging and its influence on the choice of treatment. We discuss glossopharyngeal neuralgia, other neuropathic causes of facial pain, postinflammatory and neoplastic causes, and nociceptive (end-organ) causes of facial pain, as well as referred otalgia. Other conditions that may present with facial pain, including trigeminal autonomic cephalgias and giant cell arteritis, are reviewed briefly. We discuss the elements of a comprehensive MR imaging protocol to enable detection of these diverse causes of facial pain.

Operative findings and outcome of microvascular decompression/adhesiolysis for trigeminal neuralgia in multiple sclerosis without demyelinating brain stem lesions

OBJECTIVE

Trigeminal neuralgia (TN) in multiple sclerosis (MS) poses several challenges for treatment. Although these patients often have typical attacks, they may not be considered as candidates for microvascular decompression (MVD). Here we report on surgical findings and long term follow-up of MVD/ adhesiolysis in a series of patients with multiple sclerosis but without demyelinating brain stem lesions.

METHODS

Fifteen patients with MS-related TN underwent MVD/ adhesiolysis. Demyelinating brain stem lesions were excluded radiologically. Outcome of the intervention was assessed according to the Barrow Neurological Institute (BNI) pain intensity score at 3, 12, 24 months follow-up and at the last available follow-up (mean 88.2 months, range 38-146).

RESULTS

All 15 patients benefited from MVD/adhesiolysis and were pain free on the first day of surgery. Intraoperative findings included arterial contact in 7/15 (47 %) patients, venous contact in 9/15 (60 %), and prominent arachnoid thickening in 12/15 (80 %). The distribution of the BNI pain intensity scores showed marked improvement at all follow-up evaluations. Five patients underwent repeat MVD/adhesiolysis for pain recurrence at a mean of 43 months after the first surgery. Long term evaluation at the last available follow-up demonstrated favorable outcome in 13/15 patients (BNI I-IIIa) (87 %), while 2/15 patients had limited benefit (BNI IV).

CONCLUSIONS

MS-related TN in patients without demyelinating brain stem lesions may be related either to vascular conflicts or to focal arachnoiditis at the trigeminal nerve entry zone. MVD/ adhesiolysis may be considered as a useful treatment option in this subgroup of patients with regard to long term outcome.

A segmentation-independent volume rendering visualisation method might reduce redundant explorations and post-surgical complications of microvascular decompression

OBJECTIVES

This study aimed to investigate the feasibility of segmentation-independent volume rendering (SI-VR) in visualising the root entry zone (REZ), and to explore the influence on the management of vascular compression syndromes (VCSs).

METHODS

Two hundred and twenty patients with VCSs were recruited in this prospective study from July 2015 to May 2019. SI-VR was reconstructed based on inverted 3D fast spin echo T2WI. They were assigned to the experimental group and control group randomly. Patients in the experimental group would accept extra evaluation based on SI-VR before microvascular decompression. Image quality and diagnostic accuracy between SI-VR and 3D fast spin echo T2WI in the experimental group were compared by Mann-Whitney U test and chi-square test, separately. Interobserver agreement was performed with intraclass correlation coefficient. Postsurgical outcomes and complications between two groups were compared by chi-square test.

RESULTS

SI-VR had a better interobserver agreement (0.82 vs 0.68) and diagnostic accuracy (95.5% vs 83.6%, p = 0.004) than that of 3D fast spin echo T2WI. Especially, significantly improved diagnostic accuracy was reached in detecting the multi-vascular branches compression (100% vs 15.4%, p < 0.001). There were fewer complications (7.1% vs 26.8%, p = 0.004) and less operation time (20.7 min vs 14.5 min, p = 0.007) but no significant difference of pain relief (p = 0.19) in the experimental group than in the control group.

CONCLUSIONS

The SI-VR method is feasible for the precise demonstration of the anatomy structure along the REZ, with high reliability and reproducibility. Unbiased pre-surgical visualisation could reduce redundant explorations and post-surgical complications in patients who undergo microvascular decompression.

KEY POINTS

• Visualisation of the root entry zone by the segmentation-independent volume rendering is in accordance with the landscape by the neuro-endoscopy. • Segmentation-independent volume rendering has an advantage over 3D fast spin echo T2WI in the visualisation of multi-vascular branches compression. • Presurgical 3D visualisation of the neurovascular compression at the root entry zone leads to less postsurgical complications from the decrease of redundant exploration.

Cranial Nerve Enhancement in Multiple Sclerosis Is Associated With Younger Age at Onset and More Severe Disease

Background: The overall frequency of cranial nerve pathology, including cranial nerves other than the trigeminal nerve, as well as its relation to brainstem lesion formation on magnetic resonance imaging (MRI) and clinical correlates in multiple sclerosis (MS) is unknown.

Objective: We aimed to determine the frequency of cranial nerve enhancement on MRI, and its association with brainstem lesion formation and clinical outcomes.

Methods: We retrospectively analyzed, in 183 patients, (RRMS: 156, SPMS: 15, PPMS: 6, CIS: 6) 651 MRIs (76.5% on the identical scanner Siemens Trio Tim, 3T with identical MRI protocols). Frequencies of cranial nerve enhancement on post contrast T1-weighted MRIs were compared to lesion counts and the MS-severity-score.

Results: Cranial nerve enhancement was present in 8.2% of the analyzed MS patients (oculomotor-nerve: 1.1%, trigeminal-nerve: 2.7%, abducens-nerve: 2.2%, facial-/vestibulocochlear nerve: 1.6%, vagal-nerve: 0.5%). Of those, 13% suffered from repeated episodes and 27% exhibited a cranial nerve enhancement duration of >12 months. Age at MS onset was lower in patients with cranial nerve enhancement, 23 vs. 28 years, p = 0.049. The MS-severity-score, 5.15 vs. 0.88 (p = 0.019), the T2 brainstem-, 1 vs. 0 (p = 0.041), and the total intracranial contrast-enhancing lesion counts, 2 vs. 0 (p = 0.000), were higher in patients with cranial nerve enhancement, compared to age-, disease duration-, and gender- matched MS patients.

Conclusions: Cranial nerve enhancement, present in 8.2% of our patients, was associated with a younger age at MS onset, brainstem lesions, and a more severe disease course.

Bacterial transportable toxins of the nasopharyngeal microbiota in multiple sclerosis. Nose-to-brain direct

Intranasal administration delivers molecules directly to the brain bypassing the blood-brain barrier. Three distinct routes of access have been identified; olfactory, trigeminal and via the paranasal sub-mucosa of the posterior sinuses. Consequently, environmental toxins may access the CNS directly to induce inflammatory and degenerative disease. They may also activate bacterial species of the nasal mucosal microbiome to release both immune-deviating cell wall antigens and transportable neurotoxins with local direct access to the CNS. Evidence is reviewed that toxins of the nasal bacterial microbiota may be directly implicated in the inflammatory and degenerative pathogenesis of multiple sclerosis.

Cranial Neuralgias

PURPOSE OF REVIEW

This article describes the clinical features and diagnostic criteria, pathophysiology (when known), and treatment strategies of the major cranial neuralgias.

RECENT FINDINGS

Abnormal vascular loops compressing cranial nerves are the most common known pathogenesis associated with the primary neuralgias.

SUMMARY

The most frequently encountered primary neuralgias are trigeminal neuralgia, occipital neuralgia, and, rarely, glossopharyngeal neuralgia. Nervus intermedius neuralgia is even more rare. All neuralgias merit a careful workup for secondary causes. Drug treatment generally relies on antiepileptic drugs, antidepressants, and baclofen. OnabotulinumtoxinA can be useful in treating some cranial neuralgias. Surgical and invasive treatments include ablation, gamma knife treatment, and microvascular decompression.

[Experience of the use of gasserian ganglion balloon compression in patients with trigeminal neuralgia associated with multiple sclerosis]

AIM

To evaluate the efficacy of gasserian ganglion balloon compression in patients with trigeminal neuralgia associated with multiple sclerosis (MS).

MATERIAL AND METHODS

Eight patients (3 men, 5 women), aged from 46 to 66 years (mean age 55 years), with trigeminal neuralgia associated with MS underwent surgery. An average duration of the pain syndrome was 8,4 years. Six patients had previous surgeries due to facial pain. Percutaneous balloon compression of gasserian ganglion was performed to all patients. Follow up period was from 2 to 24 months.

RESULTS

Six patients (75%) reported 100% of pain relief right after the surgery, 2 patients (25%) reported a significant decrease of pain (2-3 points on VAS). Pain recurrence occurred in 3 patients: in 4 months, in 12 months and in 6 months. All of them were operated repeatedly. After the surgery, hypoesthesia on the side of surgery was observed in all patients with a trend towards regression. There was no keratopathy or any complications.

CONCLUSION

Percutaneous balloon compression of gasserian ganglion is an effective and minimally invasive method which can be performed repeatedly in patients with trigeminal neuralgia associated with MS.

Occipital neuralgia associates with high cervical spinal cord lesions in idiopathic inflammatory demyelinating disease

BACKGROUND

The association of trigeminal neuralgia with pontine lesions has been well documented in multiple sclerosis, and we tested the hypothesis that occipital neuralgia in multiple sclerosis is associated with high cervical spinal cord lesions.

METHODS

We retrospectively reviewed the records of 29 patients diagnosed with both occipital neuralgia and demyelinating disease by a neurologist from January 2001 to December 2014. We collected data on demographics, clinical findings, presence of C2-3 demyelinating lesions, and treatment responses.

RESULTS

The patients with both occipital neuralgia and multiple sclerosis were typically female (76%) and had a later onset (age > 40) of occipital neuralgia (72%). Eighteen patients (64%) had the presence of C2-3 lesions and the majority had unilateral symptoms (83%) or episodic pain (78%). All patients with documented sensory loss (3/3) had C2-3 lesions. Most patients with progressive multiple sclerosis (6/8) had C2-3 lesions. Of the eight patients with C2-3 lesions and imaging at onset of occipital neuralgia, five (62.5%) had evidence of active demyelination. None of the patients with progressive multiple sclerosis (3/3) responded to occipital nerve blocks or high dose intravenous steroids, whereas all of the other phenotypes with long term follow-up (eight patients) had good responses.

CONCLUSIONS

A cervical spine MRI should be considered in all patients presenting with occipital neuralgia. In patients with multiple sclerosis, clinical features in occipital neuralgia that were predictive of the presence of a C2-3 lesion were unilateral episodic symptoms, sensory loss, later onset of occipital neuralgia, and progressive multiple sclerosis phenotype. Clinical phenotype predicted response to treatment.

Pattern Recognition of the Multiple Sclerosis Syndrome

During recent decades, the autoimmune disease neuromyelitis optica spectrum disorder (NMOSD), once broadly classified under the umbrella of multiple sclerosis (MS), has been extended to include autoimmune inflammatory conditions of the central nervous system (CNS), which are now diagnosable with serum serological tests. These antibody-mediated inflammatory diseases of the CNS share a clinical presentation to MS. A number of practical learning points emerge in this review, which is geared toward the pattern recognition of optic neuritis, transverse myelitis, brainstem/cerebellar and hemispheric tumefactive demyelinating lesion (TDL)-associated MS, aquaporin-4-antibody and myelin oligodendrocyte glycoprotein (MOG)-antibody NMOSD, overlap syndrome, and some yet-to-be-defined/classified demyelinating disease, all unspecifically labeled under MS syndrome. The goal of this review is to increase clinicians’ awareness of the clinical nuances of the autoimmune conditions for MS and NMSOD, and to highlight highly suggestive patterns of clinical, paraclinical or imaging presentations in order to improve differentiation. With overlay in clinical manifestations between MS and NMOSD, magnetic resonance imaging (MRI) of the brain, orbits and spinal cord, serology, and most importantly, high index of suspicion based on pattern recognition, will help lead to the final diagnosis.

Supratentorial lesions contribute to trigeminal neuralgia in multiple sclerosis

Background

It has been proposed that multiple sclerosis lesions afflicting the pontine trigeminal afferents contribute to trigeminal neuralgia in multiple sclerosis. So far, there are no imaging studies that have evaluated interactions between supratentorial lesions and trigeminal neuralgia in multiple sclerosis patients.

Methods

We conducted a retrospective study and sought multiple sclerosis patients with trigeminal neuralgia and controls in a local database. Multiple sclerosis lesions were manually outlined and transformed into stereotaxic space. We determined the lesion overlap and performed a voxel-wise subtraction analysis. Secondly, we conducted a voxel-wise non-parametric analysis using the Liebermeister test.

Results

From 12,210 multiple sclerosis patient records screened, we identified 41 patients with trigeminal neuralgia. The voxel-wise subtraction analysis yielded associations between trigeminal neuralgia and multiple sclerosis lesions in the pontine trigeminal afferents, as well as larger supratentorial lesion clusters in the contralateral insula and hippocampus. The non-parametric statistical analysis using the Liebermeister test yielded similar areas to be associated with multiple sclerosis-related trigeminal neuralgia.

Conclusions

Our study confirms previous data on associations between multiple sclerosis-related trigeminal neuralgia and pontine lesions, and showed for the first time an association with lesions in the insular region, a region involved in pain processing and endogenous pain modulation.

Multiple Sclerosis-Related Pain Syndromes: An Imaging Update

Pain in multiple sclerosis (MS) is a common manifestation, made up of complex phenomenon involving intricate neurophysiological processing at central levels of the pain pathway. Our understanding of the clinical and neurophysiological mechanisms of central/neuropathic pain related to MS continues to improve with improved imaging techniques but remains a challenging area of research. The advancements in imaging techniques for lesion evaluation of the various neuroanatomic structures have improved our detection, diagnosis, and understanding of MS pain and help validate subjective symptoms. This article will discuss the updated criteria of MS neuropathic pain and critically review some of the latest research into imaging correlations of MS pain syndromes. And discuss how advanced MRI imaging techniques (such as functional magnetic resonance imaging [fMRI], 3D imaging, fluid attenuated inversion recovery [FLAIR*], and diffusion tensor imaging [DTI]) have detailed neuropathic pain with a focus on migraines and trigeminal neuralgias and will highlight some of the ongoing limitations, variabilities, and deficiencies.

Tongue somatosensory evoked potentials reflect midbrain involvement in patients with clinically isolated syndrome

AIM

To test the hypothesis that tSSEP findings reflect clinical and MRI MS lesions, the aim of this study was to investigate tSSEP changes in patients with clinically isolated syndrome (CIS) in relation to clinical and brainstem MRI findings. The second aim was to investigate whether the interpretation of the tSSEP results in the form of the tSSEP score enables better evaluation of the afferent trigeminal pathway involvement than analyzing each tSSEP parameter separately.

METHODS

115 consecutive CIS patients were enrolled from August 1, 2014 until March 1, 2016. Facial sensory symptoms and brainstem MRI (1.5 T) lesions were analyzed. tSSEP testing was performed for each patient from the raw tSSEP data. The tSSEP score was calculated separately for the left and right side (according to the cut-off values for absent response and prolonged latency of the main component, P1 (0=normal response, 1=prolonged latency, 3=absent response) and the two values were summed.

RESULTS

There was no difference in the absolute values of the tSSEP variables regarding the presence of clinical symptoms. No association was found between tSSEP abnormalities and clinical symptoms (P=0.544). Brainstem lesions (midbrain and pons) were associated with the absent tSSEP responses (P=0.002 and P=0.005, respectively). tSSEP score was significantly higher in patients with brainstem lesions (P=0.01), especially midbrain (P=0.004) and pontine (P=0.008) lesions. Binary logistic regression showed that tSSEP score had a significant effect on the likelihood that patients have midbrain MR lesions, ?2(1)=6.804, P=0.009; and the model correctly classified 87% of cases.

CONCLUSIONS

The consistent finding of this study was the association between tSSEP and midbrain lesions on MRI, indicating that tSSEP evaluates proprioception of the face. This study establishes the value of tSSEP in assessing brainstem function in early multiple sclerosis.

Can pontine trigeminal T2-hyperintensity suggest herpetic etiology of trigeminal neuralgia?

BACKGROUND

Trigeminal neuralgia (TN) is usually classified into two different categories: idiopathic and secondary. We have investigated the frequency of brainstem pontine lesions in patients with idiopathic TN without multiple sclerosis (MS) or stroke, and their association with herpes zoster (HZ) infection.

METHODS

Brain magnetic resonance imaging (MRI) studies of 28 patients with TN were retrospectively reviewed.

RESULTS

We found seven patients with clinical suspicion of HZ infection and pontine T2 hyperintense lesions, associated with nerve atrophy in one case. Fifteen patients had a neurovascular conflict (NVC) without brainstem involvement, two of them associated with trigeminal atrophy, while four patients had only volumetric reduction of the nerve. In all patients MRI findings were ipsilateral to the side of TN.

CONCLUSIONS

Pontine T2 hyperintensities could be considered as a MRI sign of TN in patients without NVCs. This "trigeminal pontine sign" (TPS) is frequently found in association with herpetic infections.

A neurophysiological study of facial numbness in multiple sclerosis: Integration with clinical data and imaging findings

OBJECTIVE

To integrate neurophysiological findings with clinical and imaging data in a consecutive series of multiple sclerosis (MS) patients developing facial numbness during the course of an MS attack.

METHODS

Nine consecutive patients with MS and recent-onset facial numbness were studied clinically, imaged with routine MRI, and assessed neurophysiologically with trigeminal somatosensory evoked potential (TSEP), blink reflex (BR), masseter reflex (MR), facial nerve conduction, facial muscle and masseter EMG studies.

RESULTS

All patients had unilateral facial hypoesthesia on examination and lesions in the ipsilateral pontine tegmentum on MRI. All patients had abnormal TSEPs upon stimulation of the affected side, excepting one that was tested following remission of numbness. BR was the second most sensitive neurophysiological method with 6/9 examinations exhibiting an abnormal R1 component. The MR was abnormal in 3/6 patients, always on the affected side. Facial conduction and EMG studies were normal in all patients but one.

CONCLUSIONS

Facial numbness was always related to abnormal TSEPs. A concomitant R1 abnormality on BR allowed localization of the responsible pontine lesion, which closely corresponded with MRI findings. We conclude that neurophysiological assessment of MS patients with facial numbness is a sensitive tool, which complements MRI, and can improve lesion localization.

Microstructural abnormalities of the trigeminal nerve by diffusion-tensor imaging in trigeminal neuralgia without neurovascular compression

Microstructural changes of the trigeminal nerve in trigeminal neuralgia due to neurovascular compression have been reported by using diffusion tensor imaging. Other aetiologies such as primary demyelinating lesions, brain stem infarction and nerve root infiltration by tumour affecting the trigeminal pathway may also present as trigeminal neuralgia. The aim of this study was to evaluate the microstructural tissue abnormalities in the trigeminal nerve in symptomatic trigeminal neuralgia not related to neurovascular compression using diffusion tensor imaging. Mean values of the quantitative diffusion parameters of trigeminal nerve, fractional anisotropy and apparent diffusion coefficient, were measured in a group of four symptomatic trigeminal neuralgia patients without neurovascular compression who showed focal non-enhancing T2-hyperintense lesions in the pontine trigeminal pathway. These diffusion parameters were compared between the affected and unaffected sides in the same patient and with four age-matched healthy controls. Cranial magnetic resonance imaging revealed hyperintense lesions in the dorsolateral part of the pons along the central trigeminal pathway on T2-fluid-attenuated inversion recovery sequences. The mean fractional anisotropy value on the affected side was significantly decreased (P = 0.001) compared to the unaffected side and healthy controls. Similarly, the mean apparent diffusion coefficient value was significantly higher (P = 0.001) on the affected side compared to the unaffected side and healthy controls. The cause of trigeminal neuralgia in our patients was abnormal pontine lesions affecting the central trigeminal pathway. The diffusion tensor imaging results suggest that microstructural tissue abnormalities of the trigeminal nerve also exist even in non-neurovascular compression-related trigeminal neuralgia.

A case of mental nerve paresthesia due to dynamic compression of alveolar inferior nerve along an elongated styloid process

Spontaneous paresthesia of the mental nerve is considered an ominous clinical sign. Mental nerve paresthesia has also been referred to as numb chin syndrome. Several potentially different factors have been investigated for their role in interfering with the inferior alveolar nerve (IAN) and causing mental nerve neuropathy. In the present case, the patient had an elongated calcified styloid process that we hypothesized had caused IAN irritation during mandibular movement. This eventually resulted in progressive loss of sensation in the mental nerve region. To our knowledge, this dynamic irritation, with complete recovery after resection of the styloid process, has not been previously reported.

Tongue somatosensory-evoked potentials: evaluation of the afferent trigeminal pathway in patients with early multiple sclerosis

The aim of this study was to determine the efficacy of tongue somatosensory-evoked potentials (tSSEPs) in evaluation of afferent trigeminal pathway in patients with early multiple sclerosis (MS). The tSSEP was performed on 10 healthy volunteers and 10 patients with the first symptom of MS. Data were compared between the groups, and tSSEP findings of patients with MS were correlated with clinical and magnetic resonance imaging (MRI) data. Among 10 patients, 2 (20%) had clinically evident involvement of the brainstem, 5 (50%) had brainstem lesions on brain MRI, while 9 (90%) had prolonged latencies on tSSEP. Of the 8 patients with no clinical evidence of brainstem pathology, 7 (88%) had prolonged latencies/conduction block on tSSEP. Patients had statistically significant prolongation of N1, P1, and N2 latencies for stimulation of the right side and N2 latency for stimulation of the left side compared to healthy controls. The tSSEP is an efficient method for evaluating the afferent trigeminal pathway in patients with early MS. This study provides evidence that lesions of the afferent trigeminal pathway are more frequently found by tSSEP than by clinical examination or MRI.

Outcomes after microvascular decompression for patients with trigeminal neuralgia and suspected multiple sclerosis

BACKGROUND

Microvascular decompression (MVD) is an established surgical therapy for patients with idiopathic trigeminal neuralgia (TN). The role of MVD in patients with definite or suspected multiple sclerosis (MS) remains controversial.

METHODS

During the period 2000-2012, 10 patients with medically refractory TN and ipsilateral brainstem T2 hyperintensity underwent MVD. In 5 patients, additional clinical features suspicious for MS were present, including prior optic neuritis (n = 2), multiple disseminated lesions (n = 3), and elevated immunoglobulin G index (n = 2). One patient had failed prior percutaneous surgery; 1 patient had Burchiel type 2 TN. Follow-up (median, 14 months) was censored at the time of additional surgery (n = 6) or last clinic visit (n = 4).

RESULTS

Neurovascular compression was confirmed at surgery from the superior cerebellar artery (SCA) plus adjacent vein (n = 4), vein alone (n = 3), SCA alone (n = 2), and SCA plus anterior inferior cerebellar artery (n = 1). Initially after MVD, 8 patients (80%) were pain-free and subsequently tapered off medications for their facial pain. Pain recurred in 6 patients at a median of 4 months (range, 1-23 months). Actuarial rates of being pain-free off medications were 50% at 3 months and 15% at 2 years. In 6 patients, additional treatments were performed, including glycerol rhizotomy (n = 4), radiosurgery (n = 2), balloon compression (n = 2), and repeat MVD (n = 1). At last contact, 5 of the 6 patients who were retreated were pain-free.

CONCLUSIONS

Facial pain outcomes after MVD in patients with suspected MS-related TN are poor compared with outcomes for patients with idiopathic TN. This study provides further support that many patients with MS-related TN have pain that is centrally mediated, reducing the effectiveness of procedures performed on the trigeminal root, ganglion, or divisions.

Central nervous system infectious diseases mimicking multiple sclerosis: recognizing distinguishable features using MRI

The current diagnostic criteria for multiple sclerosis (MS) confirm the relevant role of magnetic resonance imaging (MRI), supporting the possibility of characterizing the dissemination in space (DIS) and the dissemination in time (DIT) in a single scan. To maintain the specificity of these criteria, it is necessary to determine whether T2/FLAIR visible lesions and the gadolinium enhancement can be attributed to diseases that mimic MS. Several diseases are included in the MS differential diagnosis list, including diseases with exacerbation, remitting periods and numerous treatable infectious diseases, which can mimic the MRI features of MS. We discuss the most relevant imaging features in several infectious diseases that resemble MS and examine the primary spatial distributions of lesions and the gadolinium enhancement patterns related to MS. Recognizing imaging "red flags" can be useful for the proper diagnostic evaluation of suspected cases of MS, facilitating the correct differential diagnosis by assessing the combined clinical, laboratory and MR imaging information.

Surgical Outcomes of Trigeminal Neuralgia in Patients With Multiple Sclerosis

BACKGROUND:

Trigeminal neuralgia (TN) is relatively frequent in multiple sclerosis (MS) patients and can be extremely disabling. Surgical interventions are less effective for the treatment of MS-related TN compared with classic TN, and higher recurrence rates are observed.

OBJECTIVE:

To evaluate initial pain-free response (IPFR), duration of pain-free intervals (PFIs), and factors predictive of outcome in different surgical modalities used to treat MS-related TN.

METHODS:

A total of 96 MS patients underwent 277 procedures (range, 1–11 procedures per patient) to treat TN at our institution from 1995 to 2011. Of these, 89 percutaneous retrogasserian glycerol rhizotomies, 82 balloon compressions, 52 stereotactic radiosurgeries, 28 peripheral neurectomies, 15 percutaneous radiofrequency rhizotomies, and 10 microvascular decompressions were performed as upfront or repeat treatments.

RESULTS:

Bilateral pain was observed in 10% of patients during the course of disease. During the follow-up period (median, 5.7 years), recurrence of symptoms was seen in 66% of patients, and 181 procedures were performed for symptom recurrence. As an initial procedure, balloon compression had the highest IPFR (95%; P = .006) and median PFI (28 months; P = .05), followed by percutaneous retrogasserian glycerol rhizotomy (IPFR, 74%, P = .04; median PFI, 9 months; P = .05). In general, repeat procedures had lower effectiveness compared with initial procedures, with no statistically significant difference seen across the various treatment modalities.

CONCLUSION:

Treatment failure occurs in most of the MS-related TN patients independently of the type of treatment. However, balloon compression had the highest rate of IPFR and PFI compared with other modalities in the initial treatment of MS-related TN.

MRI characteristics of trigeminal nerve involvement in patients with multiple sclerosis

BACKGROUND

Trigeminal neuralgia and central sensory disturbances are common in patients with multiple sclerosis. The anatomic correlation to lesions in the trigeminal nuclei in the brainstem is not well studied.

OBJECTIVE

We studied the anatomical characteristics of demyelinating lesions of the trigeminal complex in the brainstem on MRI in patients with MS and Clinically Isolated syndrome (CIS).

MATERIALS AND METHODS

43 Patients with MS or CIS and MRI lesions in the trigeminal complex in the brainstem were selected from a large database of patients referred for MRI because of trigeminal symptoms.

RESULTS AND CONCLUSION

A linear plaque involving the intrapontine fascicular part of the trigeminal nerve and lesions of the spinal trigeminal nucleus and tract seem to be distinctive MRI findings in patients with RRMS or CIS.

Optimized double inversion recovery for reduction of T₁ weighting in fluid-attenuated inversion recovery

Fluid-attenuated inversion recovery (FLAIR) is a routinely used technique in clinical practice to detect long T(2) lesions by suppressing the cerebrospinal fluid. Concerns remain, however, that the inversion pulse in FLAIR imparts T(1) weighting that can decrease the detectability and mischaracterize some lesions. Hence, FLAIR is usually acquired in conjunction with a standard T(2) to guard against these concerns. Recently, double inversion recovery (DIR) preparations have highlighted certain types of lesions by suppressing both cerebrospinal fluid and white matter but produce even stronger T(1) contrast than FLAIR. This work shows that the inversion times in a DIR sequence can be optimized to minimize unwanted T(1) weighting, enabling the acquisition of cerebrospinal fluid-suppressed images with pure T(2) weighting. This technique is referred to as T(1) -nulled DIR. The theory to determine the optimized inversion times is discussed and the results are shown by simulations, normal volunteer studies, and multiple sclerosis patient studies. T(1) -nulled DIR provides equivalent or superior contrast between gray and white matters as well as white matter and multiple sclerosis lesion at the same repetition time. Multiple sclerosis lesions appeared sharper on T(1) -nulled DIR compared to FLAIR. T(1) -nulled DIR has the potential to replace the combination of standard T(2) and FLAIR acquisitions in many clinical protocols.