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CASE REPORT
Year : 2019  |  Volume : 67  |  Issue : 1  |  Page : 169-172

Ictal FDGPET and SPECT in hemifacial seizures due to cerebellar epilepsy—Case report


1 Department of Neurology, Krishna Institute of Medical Sciences, Secunderabad, Telangana, India
2 Department of Paediatric Neurology, Rainbow Children's Hospital, Hyderabad, India
3 Department of Nuclear Medicine, Krishna Institute of Medical Sciences, Secunderabad, Telangana, India
4 Department of Neurosurgery, Krishna Institute of Medical Sciences, Secunderabad, Telangana, India

Date of Web Publication7-Mar-2019

Correspondence Address:
Dr. Sita Jayalakshmi
Department of Neurology, Krishna Institute of Medical Sciences, 1-8-31/1, Ministers Road, Secunderabad - 500 003, Telangana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.253622

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 » Abstract 


The role of cerebellum in seizure generation is debatable. Semiology and electroencephalography (EEG) findings are non-specific and sometimes misleading, posing further difficulty in proving the epileptogenicity in pre-surgical workup. We report two cases of cerebellar lesions who presented with hemifacial seizures since the neonatal period and were refractory to antiepileptic drugs (AEDs). Both inter-ictal and ictal EEGs were non-contributory. Magnetic resonance imaging (MRI) showed a lesion in the cerebellum, in proximity to cerebellar peduncle in both the patients. (18) F-fluorodeoxyglucose–positron emission tomography (FDG-PET) and ictal single photon emission computed tomography (SPECT) showed focal hypermetabolism and hyperperfusion respectively, corresponding to the lesion on MRI in both the cases. Intraoperative electrocorticography showed rhythmic spikes confirming the epileptogenic nature of the lesion. Both patients were operated with a favorable surgical outcome. Histopathology was suggestive of a ganglioglioma in one child and a low-grade glioma in the other. Both cases illustrate that FDG-PET and SPECT can act as surrogate markers for invasive recordings to prove the epileptogenicity of cerebellar lesions, especially in resource limited settings.


Keywords: Cerebellar, epilepsy, FDG-PET, hemifacial seizures, SPECT
Key Message: Cerebellar lesions can cause epilepsy especially when they are in close proximity to the cerebellar peduncle. FDG-PET and SPECT can substitute for invasive recordings to prove the epileptogenicity of cerebellar lesions.


How to cite this article:
Gupta S, Jayalakshmi S, Lingappa L, Konanki R, Vooturi S, Sudhakar P, Panigrahi M. Ictal FDGPET and SPECT in hemifacial seizures due to cerebellar epilepsy—Case report. Neurol India 2019;67:169-72

How to cite this URL:
Gupta S, Jayalakshmi S, Lingappa L, Konanki R, Vooturi S, Sudhakar P, Panigrahi M. Ictal FDGPET and SPECT in hemifacial seizures due to cerebellar epilepsy—Case report. Neurol India [serial online] 2019 [cited 2019 Sep 15];67:169-72. Available from: http://www.neurologyindia.com/text.asp?2019/67/1/169/253622




Epilepsy mainly arises from the cerebral cortex. Subcortical lesions are generally considered coincidental. A subcortical origin, though debatable, has been postulated with reports of seizure onset from a hypothalamic hamartoma [1] and cerebellar dysplastic lesions.[2],[3] Epileptogenicity of subcortical structures is postulated from either aberrant connectivity of neuronal structures or from the intrinsic epileptogenicity of dysplastic neurons.[4] Interictal and ictal electroencephalography (EEG) data are mostly non-contributory in these cases, posing difficulty in the pre-surgical workup. We report the findngs on two operated cases of cerebellar refractory epilepsy and highlight the role of ictal (18) F-fluorodeoxyglucose–positron emission tomography (FDG-PET) and ictal single photon emission computed tomography (SPECT) in establishing the epileptogenicity of the cerebellar lesion.


 » Cases Top


Case 1

A 4-month old male infant had seizures since 1 month of age with a frequency of 6 to 8 seizures per day, which increased to 15 to 20 per hour over the next 1 month. The seizure began with left eye blinking, followed by left face jerking and head and eye deviation to the left, with dystonic posturing of the left upper limb and lower limb for 1 to 3 minutes. He had hypersalivation with tachypnea during these episodes. The child was unresponsive for a few minutes and then became playful. Transient post ictal weakness of the left upper and lower limbs was noted. He failed multiple antiepileptic drugs (AEDs). He attained a social smile. His birth history was unremarkable. The inter-ictal EEG showed right hemispherical 2-3 Hz slow wave activity. Ictal EEG showed a right hemispherical 2-3 Hz slow wave activity. Ictal EEG showed right hemispherical 2-3 Hz slow wave activity during the entire event. Magnetic resonance imaging (MRI) of the brain revealed a non-enhancing left cerebellar mass involving the uvula, pyramid, medial aspect of middle and superior cerebellar peduncle, and inferior colliculus, extending up to the midline [Figure 1]a and [Figure 1]b. Ictal SPECT revealed focal lesional hyperperfusion while ictal FDG-PET study showed focal hypermetabolism [Figure 1]c and [Figure 1]d. The child underwent bilateral sub-occipital craniotomy with near-total excision of the left cerebellar lesion. Rhythmic spike discharges were noted on electrocorticography (ECoG) during depth electrode monitoring. The histopathology was a low-grade ganglioglioma. The child was seizure-free for 6 months, and at a 6-year follow-up, getting occasional brief left hemifacial jerks. He was going to school, able to communicate well, and was on three anti-epileptic drugs (AEDs).
Figure 1: Case 1: (a and b): Axial and coronal MRI sequences showing the left cerebellar mass lesion (arrow); (c and d): Ictal SPECT and ictal FDG-PET images showing focal hyperperfusion and hypermetabolism corresponding to the area of the cerebellar lesion (arrow)

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Case 2

A 2-year and 2-month-old child presented with seizures since 10 days of birth. Seizures start with right eye blinking and right face jerking lasting for a few seconds. Initially, the frequency was 5 to 10 per day, which increased to 5 to 6 per hour. His birth and developmental history was normal. Interictal EEG was suggestive of occasional left frontal and parasagittal sharp wave discharges. The ictal EEG was suggestive of left frontal and parasagittal ictal onset. MRI revealed a right cerebellar, right middle cerebellar peduncle, juxta- and intra-fourth ventricular space occupying lesion [Figure 2]a and [Figure 2]b. Ictal FDG-PET CT was suggestive of hypermetabolic focus in the area of the lesion and ictal SPECT revealed hyperperfusion [Figure 2]c, [Figure 2]d and [Figure 2]e. Epileptiform discharges were recorded during intra-operative ECoG with depth recordings from the lesion. The child underwent surgery, and resection of the lesion was done. Post surgery, he was completely seizure-free at a 4-year follow-up with normal milestone development and was going to school. Histopathology was suggestive of a low-grade glioma.
Figure 2: Case 2: (a and b): Axial and sagittal MRI sequences: Arterial spin labelling MR perfusion, showing left cerebellar mass lesion (arrow); (c,d and e): Ictal SPECT and interictal FDG-PET images showing focal hyperperfusion and hypermetabolism corresponding to the area of the lesion (arrow)

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 » Discussion Top


The two cases highlight that refractory epilepsy may occur due to a cerebellar lesion. They highlight the importance of PET and SPECT imaging in confirming the epileptogenicity of the lesion. In 1871, John Hughlings Jackson first described a 5-year-old boy with a tuberculous abscess of the middle lobe of cerebellum, presenting with tonic seizures, introducing for the first time the concept of “cerebellar seizures” that was distinct from “cerebral epilepsy”.[5] Harvey et al., in their seminal paper proposed a unique clinicopathologic syndrome of hemifacial seizures and cerebellar ganglioglioma occurring in infancy.[2] During the late half of the 20th century and early 21st century, many authors published clinical cases of seizures in the setting of cerebellar tumors.[6],[7] Recently, Foit et al., had reviewed 29 case reports of a total of 31 patients with lesional cerebellar epilepsy.[8]

While the role of hypothalamic hamartoma in epilepsy is well established, the role of cerebellar glioneuronal tumors (GNTs) is considered elusive.[8] This is due to various reasons. First, the cerebellum is a subcortical structure with low epileptogenic potential. It is supposed to exert a modulatory effect on epileptic seizures, rather than being the primary seizure generator. Second, the routine pre-surgical evaluation including the semiology characterization and EEG evaluation has a poor or almost negligible contribution in defining the role of cerebellum in causing epilepsy. Scalp EEG, assessing both interictal and ictal EEG, is mostly normal or non-localizing in these cases.[8] Neither is the semiology a characteristic one. Different types of seizure semiology can be seen. Hemifacial seizures are the most common manifestations and can be confused with movement disorders.[9] Myoclonic seizures and focal or generalized seizures are other uncommon seizure types. Myoclonic and generalized seizures do not give a clue to lateralization, and even in focal seizures, the semiology is paradoxically ipsilateral to the side of lesion (e.g., a left-sided cerebellar lesion can cause left focal seizures). All these factors pose a difficulty in proving the role of cerebellar lesions in causing epilepsy during the non-invasive pre-surgical evaluation.

Nuclear imaging studies in the recent times may help to circumvent this problem. Positive FDG-PET and ictal SPECT have been shown to be highly suggestive of the propagating epileptic activity, providing complementary pre-surgical information that matched video-EEG results and clinical data in cerebral seizures.[10],[11] This utility of nuclear imaging is even more useful in cases of cerebellar epilepsy where video-EEG results and clinical data may fail to prove its epileptogenicity. In both our cases, ictal FDG-PET demonstrated well-localized hypermetabolism concordant with the MRI lesion. This was demonstrated earlier on, in a few studies. Lascano et al., reported a 14-month-old girl presenting with hemifacial spasm and employed electric source imaging, which was in concordance with the nuclear imaging findings, and subsequently validated by the intra-operative intralesional recordings to prove the epileptogenicity of cerebellar lesion.[12] They suggested that hemispheric cerebellar lesions in cases like this are likely to cause epilepsy via an effect on the facial nuclei through ipsilateral and contralateral aberrant connections. Similar findings were reported in another study of a 4-month-old infant with paroxysmal facial contractions; the positron emission tomography with (18) F-FDG revealed focal hypermetabolism in the same area identified by MRI, subsequently proven by invasive recordings.[7] On the same lines, ictal SPECT showed focal hyperperfusion in the area of the lesion in both our patients, similar to the few cases reported previously.[2] Hanai et al., had reported a case of refractory hemifacial seizures in which MRI revealed a large tumor in the left middle cerebellar peduncle, and ictal SPECT and ictal (18) F-FDG PET revealed hyperperfusion and hyper-glucose metabolism at the tumor site. Total removal of the tumor resulted in complete disappearance of hemifacial seizures and improved psychomotor development, indicating that the cerebellar tumor caused hemifacial seizures.[6] In all these studies, the semiology and EEG data were not useful in localizing the epileptogenic zone, and epileptogenicity was finally proven by invasive recordings. Considering all this information and our experience, we hereby postulate that ictal FDG-PET and ictal SPECT studies will confirm the epileptogenic nature of the cerebellar lesions and obviate the need for an invasive evaluation.

Glial-neuronal tumors (GNTs) and hamartomas are responsible for the most common lesional cerebellar epilepsies reported. Other common lesions include low-grade gliomas. Evidence is growing that cerebellar tumors have dysplastic neurons which are inherently epileptogenic.[2] Whether intrinsic epileptogenicity [13] or peritumoral focal cortical dysplasias (FCD)[14] are the focus of ictal onset is uncertain. Some even suggest the term 'dysplastic cerebellar epilepsy' as it is felt that GNTs and FCD form a continuum.[15] The outcome of surgical management of cerebellar epilepsy is favorable, with about 78% patients achieving an Engel I outcome at a 3-month follow-up. The best timing of surgery is not known.[8],[16]

Another important issue is that epilepsy is not seen in all cerebellar lesions or tumors. One of the reasons cited is the location within the cerebellum. The reported cases of “cerebellar epilepsy” had lesions close to cerebellar peduncles,[8] similar to the two cases in the present report. Proximity to cerebellar peduncles, which are the main efferent fiber tracts, may be important for plausible epileptogenic connections with other areas of the brain.[8] It would be interesting to study the role of nuclear imaging in predicting which cerebellar lesions will be epileptogenic.


 » Conclusion Top


Lesions of subcortical structures like the cerebellum can cause epilepsy especially when they are in close proximity to the peduncles. Ictal FDG-PET and ictal SPECT studies are important non-invasive methods in the pre-surgical evaluation to confirm the epileptogenicity of the cerebellar lesion.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
 » References Top

1.
Wu J, Gao M, Shen J-X, Qiu S, Kerrigan JF. Mechanisms of intrinsic epileptogenesis in human gelastic seizures with hypothalamic hamartoma. CNS Neurosci Ther 2015;21:104-11.  Back to cited text no. 1
    
2.
Harvey AS, Jayakar P, Duchowny M, Resnick T, Prats A, Altman N, et al. Hemifacial seizures and cerebellar ganglioglioma: An epilepsy syndrome of infancy with seizures of cerebellar origin. Ann Neurol 1996;40:91-8.  Back to cited text no. 2
    
3.
McLone DG, Stieg PE, Scott RM, Barnett F, Barnes PD, Folkerth R, et al. Cerebellar epilepsy: Case presentation. Neurosurg 1998;42:1106-11.  Back to cited text no. 3
    
4.
Palmini A, Gambardella A, Andermann F, Dubeau F, da Costa JC, Olivier A, et al. Intrinsic epileptogenicity of human dysplastic cortex as suggested by corticography and surgical results. Ann Neurol 1995;37:476-87.  Back to cited text no. 4
    
5.
McCrory PR, Bladin PF, Berkovic SF. The cerebellar seizures of Hughlings Jackson. Neurology 1999;52:1888-90.  Back to cited text no. 5
    
6.
Hanai S, Okazaki K, Fujikawa Y, Nakagawa E, Sugai K, Sasaki M, et al. Hemifacial seizures due to ganglioglioma of cerebellum. Brain Dev 2010;32:499-501.  Back to cited text no. 6
    
7.
Chae JH, Kim SK, Wang KC, Kim KJ, Hwang YS, Cho BK. Hemifacial seizure of cerebellar ganglioglioma origin: Seizure control by tumor resection. Epilepsia 2001;42:1204-7.  Back to cited text no. 7
    
8.
Foit NA, van Velthoven V, Schulz R, Blümcke I, Urbach H, Woermann FG. Lesional cerebellar epilepsy: A review of the evidence. J Neurol 2017;264:1-10.  Back to cited text no. 8
    
9.
Specchio N, Trivisano M, Bernardi B, Marras CE, Faggioli R, Fiumana E, et al. Neonatal hemifacial spasm and fourth ventricle mass. Dev Med Child Neurol 2012;54:697-703.  Back to cited text no. 9
    
10.
Perissinotti A, Setoain X, Aparicio J, Rubí S, Fuster BM, Donaire A, Carreño M. Clinical role of subtraction ictal SPECT coregistered to MR imaging and (18)F-FDG PET in pediatric epilepsy. J Nucl Med 2014;55:1099-105.  Back to cited text no. 10
    
11.
Desai A, Bekelis K, Thadani VM, Roberts DW, Jobst BC, Duhaime AC. Interictal PET and ictal subtraction SPECT: Sensitivity in the detection of seizure foci in patients with medically intractable epilepsy. Epilepsia 2013;54:341-50.  Back to cited text no. 11
    
12.
Lascano AM, Lemkaddem A, Granziera C, Korff CM, Boex C, Jenny B. Tracking the source of cerebellar epilepsy: Hemifacial seizures associated with cerebellar cortical dysplasia. Epilepsy Res 2013;105:245-9.  Back to cited text no. 12
    
13.
Barba C, Coras R, Giordano F, Buccoliero AM, Genitori L, Blümcke I, et al. Intrinsic epileptogenicity of gangliogliomas may be independent from co-occurring focal cortical dysplasia. Epilepsy Res 2011;97:208-13.  Back to cited text no. 13
    
14.
Ferrier CH, Aronica E, Leijten FSS, Spliet WGM, van Huffelen AC, van Rijen PC, et al. Electrocorticographic discharge patterns in glioneuronal tumors and focal cortical dysplasia. Epilepsia 2006;47:1477-86.  Back to cited text no. 14
    
15.
Martins WA, Paglioli E, Hemb M, Palmini A. Dysplastic cerebellar epilepsy: Complete seizure control following resection of a ganglioglioma. Cerebellum 2016;15:535-41.  Back to cited text no. 15
    
16.
Klinger NV, Shah AK, Mittal S. Management of brain tumorrelated epilepsy. Neurol India 2017;65, Suppl S1:6070  Back to cited text no. 16
    


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