Synchronous supratentorial and infratentorial oligodendrogliomas with incongruous IDH1 mutations, a case report

Infratentorial oligodendrogliomas, a rare pathological entity, are generally considered metastatic lesions from supratentorial primary tumors. Here, we report the case of a 23-year-old man presenting with a histopathologically confirmed right precentral gyrus grade 2 oligodendroglioma and a concurrent pontine grade 3 oligodendroglioma. The pontine lesion was biopsied approximately a year after the biopsy of the precentral lesion due to disease progression despite 4 cycles of procarbazine-CCNU-vincristine (PCV) chemotherapy and stable supratentorial disease. Histology and genetic analysis of the pontine biopsy were consistent with grade 3 oligodendroglioma, and comparison of the two lesions demonstrated common 1p/19q co-deletions and TERT promoter mutations but distinct IDH1 mutations, with a non-canonical IDH1 R132G mutation identified in the infratentorial lesion and a R132H mutation identified in the cortical lesion. Initiation of Temozolomide led to complete response of the supratentorial lesion and durable disease control, while Temozolomide with subsequent radiation therapy of 54 Gy in 30 fractions resulted in partial response of the pontine lesion. This case report supports possible distinct molecular pathogenesis in supratentorial and infratentorial oligodendrogliomas and raises questions about the role of different IDH1 mutant isoforms in explaining treatment resistance to different chemotherapy regimens. Importantly, this case suggests that biopsies of all radiographic lesions, when feasible and safe, should be considered in order to adequately guide management in multicentric oligodendrogliomas.

Trigeminal Neuralgia Associated With a Solitary Pontine Lesion: A Case Report

Trigeminal neuralgia associated with brainstem lesions is currently considered as a rare condition and only few patients have been reported so far in literature. Tohyama and colleagues recently proposed the nosological entity of trigeminal neuralgia associated with solitary pontine lesion, trying to categorize it as a new clinical syndrome on its own. Based on this description, trigeminal neuralgia associated with solitary pontine lesion patients have an identical clinical presentation compared to other patients with trigeminal neuralgia but have a solitary pontine lesion. The nature of the pontine lesion has been attributed to several etiologies, including ischemia, demyelination or previous pontine viral neuritis. In those patients with a putative demyelinating lesion, a definite diagnosis of multiple sclerosis cannot be made due to the lack of dissemination in space. Very little is known in relation to the cerebrospinal fluid characteristics of this population of patients. We present a case of a 42-year-old man suffering of trigeminal neuralgia associated with solitary pontine lesion with a possible demyelinating etiology. The patient herein described had an atypical trigeminal neuralgia associated with a single pontine lesion. The MRI characteristics of the lesion, along with the presence of oligoclonal bands in the cerebrospinal fluid, suggested a demyelinating etiology. Trigeminal neuralgia associated with a solitary pontine lesion may be categorized as a possible manifestation of solitary sclerosis. Future research need to reveal which features can predict the risk of conversion to clinically defined multiple sclerosis and which treatments modify this risk.

DIPG-23. SINGLE CASE REPORT OF LOW DOSE RADIOTHERAPY AND CHEMOTHERAPY IN THE TREATMENT OF DIPG

A 3 year-old girl, was noted to have progressive gait problem since Nov. 2017 and brought to hospital for checkup. Brain MRI on Jan. 2018 showed T2 hyperintensity infiltrative pontine lesion, favoring diffuse infiltrative pontine glioma and mild obstructive hydrocephalus, received VP-shunting on Jan. 15, 2018. Due to the refusal of surgical biopsy for tissue proof, we started the radiotherapy from Jan. 24, 2018, using Rapidarc technique with 6MV photon energy to treat the brain stem lesion, ended on Feb. 24, 2018 with total dose of 25.5Gy in 17 fractions as our usual practice. Following the completion of radiotherapy, we started the adjuvant chemotherapy using 1-week on, 1-week off regimen of temozolomide using dosage of 75 mg/sq-m/day, and this patient’s general condition returned back to nearly normal. Serial follow-up images of brain MRI on 04/30/2018, 08/01/2018, 11/30/2018, 02/26/2019, 05/30/2019, 08/28/2019 showed slow progression of the pontine lesion, without the development of contrast enhanced new lesion. She maintained the functional independent until Sep. 2019, she was noted to have symptoms of ataxic gait, esotropia and choking on drinking liquid. We started the retreatment of radiotherapy from Oct.7, 2019, using same technique, ended on Nov. 5, 2019 with total dose of 30Gy in 20 fractions. The symptoms improved partially after the treatment, with residual weakness over left extremity. We are still treating the patient with adjuvant temozolomide, and she has survived most of time functionally independent in these 2 years.

Dancing larynx syndrome associated with trigeminal neuralgia secondary to multiple sclerosis

A 44-year-old man with multiple sclerosis (MS) presented with focal myoclonus of the mylohyoid and anterior belly of the digastric known as “dancing larynx” [1] which began after gamma knife radiation to the left trigeminal nerve root administered for trigeminal neuralgia (Video 1,). MRI brain showed T2 hyperintensity in the left cerebellopontine angle which expanded following radiation (Figure 1). He received botulinum toxin injections in the mylohyoid muscles with resolution of the movements. The “dancing larynx” was likely from irritation of the trigeminal nerve motor root or pons itself caused by the pontine lesion that enlarged after radiation.

The role of pontine lesion location in differentiating multiple sclerosis from vascular risk factor-related small vessel disease

Background: Differentiating multiple sclerosis (MS) from vascular risk factor (VRF)-small vessel disease (SVD) can be challenging. Objective and Methods: In order to determine whether or not pontine lesion location is a useful discriminator of MS and VRF-SVD, we classified pontine lesions on brain magnetic resonance imaging (MRI) as central or peripheral in 93 MS cases without VRF, 108 MS patients with VRF and 43 non-MS cases with VRF. Results: MS without VRF were more likely to have peripheral pons lesions (31.2%, 29/93) than non-MS with VRF (0%, 0/43) (Exp( B) = 29.8; 95% confidence interval (CI) = (1.98, 448.3); p = 0.014) but there were no significant differences regarding central pons lesions between MS without VRF (5.4%, 5/93) and non-MS with VRF patients (16.3%, 7/43) (Exp( B) = 0.89; 95% CI = (0.2, 3.94); p = 0.87). The presence of peripheral pons lesions discriminated between MS and VRF-SVD with 100% (95% CI = (91.8, 100)) specificity. The proportion of peripheral pons lesions in MS with VRF (30.5%, 33/108) was similar to that seen in MS without VRF (31.2%, 29/93, p = 0.99). Central lesions occurred in similar frequency in MS with VRF (8.3%, 9/108) and non-MS with VRF (16.3%, 7/43, p = 0.15). Conclusion: Peripheral pons lesion location is a good discriminator of MS from vascular lesions.

A Case Report: Isolated Pontine Lesion in Hypertensive of a Pregnant Patient with Idiopathic Thrombocytopenia

Posterior reversible encephalopathy syndrome (PRES) is a neuroradiologic diagnosis characterised by headache, seizures, altered mental status, and a spectrum of visual deficits ranging from visual neglect to cortical blindness. PRES manifestation is a situation of medical emergency; however, it is a fully reversible condition, especially when diagnosed and treated immediately. The main problem lies in the impairment of cerebral blood flow autoregulation which, in turn, leads to endothelial dysfunction and vasogenic brain oedema. MRI indicates cerebral oedema in the occipital, temporal, and parietal lobes. Brainstem involvement is very rare in the literature. Idiopathic thrombocytopenia-related PRES is also rare in the literature. In this article, a case of PRES with only pons involvement in MRI after hypertensive attack in a pregnant patient with idiopathic thrombocytopenia is presented. PRES may present only brainstem involvement, as seen in this present case. Whether or not mild hypertension and mild thrombocytopenia found in this case are associated with limited disease should be evaluated. Prolonged spreading depression may have a role in the pathophysiology of PRES.