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Table of Contents    
LETTERS TO EDITOR
Year : 2018  |  Volume : 66  |  Issue : 3  |  Page : 871-873

Primary cerebellar agenesis in a normal man


Department of Radiology, SKIIMS, Soura, Jammu and Kashmir, India

Date of Web Publication15-May-2018

Correspondence Address:
Dr. Shah Omair
Department of Radiology, SKIIMS, Soura, Jammu and Kashmir
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.232287

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How to cite this article:
Omair S, Arif W, Muiez B, Jan S, Musaib D, Tariq G. Primary cerebellar agenesis in a normal man. Neurol India 2018;66:871-3

How to cite this URL:
Omair S, Arif W, Muiez B, Jan S, Musaib D, Tariq G. Primary cerebellar agenesis in a normal man. Neurol India [serial online] 2018 [cited 2018 May 20];66:871-3. Available from: http://www.neurologyindia.com/text.asp?2018/66/3/871/232287




Sir,

Primary cerebellar agenesis is a very rare entity. Our case is unique in that the adult who presented for a CT scan after sustaining trauma, had no motor impairment, and was found to be having an absence of cerebellum on computed tomography (CT).[1],[2],[3] The clinical presentation of this entity is highly variable. Mild-to-profound motor impairment, as well as mental and behavioral abnormalities have been described in these patients.[2] We report a case of primary cerebellar agenesis presenting with isolated cognitive impairment. Most cases with cerebellar agenesis are diagnosed in the prenatal or early postnatal period and are associated with other central nervous system abnormalities. Patients having this entity with no motor abnormalities are extremely rare. We report the clinical, neuropsychiatric, and imaging findings associated with cerebellar agenesis in an adult living patient.

A 45-year old male patient presented to our emergency department as a case of head trauma. A CT head [CT 64 Somatom] was performed as a part of the trauma protocol. No evidence of any trauma associated finding was seen; however, a complete absence of bilateral cerebellar hemispheres was noted [Figure 1], [Figure 2], [Figure 3]. A small remnant of vermis was seen in the midline [Figure 4]. On further evaluation, a hypoplastic brain stem and an empty sella were also noted [Figure 5]. The posterior fossa was normal sized with no evidence of torcular-lambdoid inversion, ruling out the presence of Dandy Walker malformation. No evidence of herniation of the occipital lobe or any evidence of meningocele was seen, ruling out Arnold– Chiari malformation More Detailss. Bilateral basal ganglia and thalami were normal [Figure 6]. Corpus callosum and cerebral hemispheres were normal. There was no ventriculomegaly.A detailed history was obtained from the guardian, who revealed that the patient had cognitive impairment in the form of a poor scholastic performance leading to his dropping out of school. The birth was by a normal vaginal delivery. There was no history of any difficulty in walking or in carrying out routine daily activities. The clinical and neurological examination revealed no motor impairment. No evidence of ataxia, dysarthria, nystagmus, or intention tremor was noted. The Romberg's test was negative and deep tendon reflexes were normal. Magnetic resonance imaging (MRI) was advised; however, the patient was claustrophobic and refused the conduction of the test. The guardians were also reluctant to subject the patient to anesthesia or sedation. A diagnosis of primary cerebellar agenesis with a small remnant of vermis was made and the patient was discharged. The patient is on a regular follow-up at our center.
Figure 1: Axial NCCT head image showing empty posterior fossa (arrow), absence of cerebellar hemispheres, normal sized posterior fossa

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Figure 2: Coronal NCCT head image showing empty posterior fossa, absence of cerebellar hemispheres, normal sized posterior fossa

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Figure 3: Sagittal NCCT head image showing empty posterior fossa, absence of cerebellar hemispheres, normal sized posterior fossa and no evidence of any herniation of cerebral hemisphere (occipital lobe)

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Figure 4: Sagittal NCCT head showing a small remnant of vermis and hypoplastic brainstem

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Figure 5: Axial NCCT head showing empty sella (arrow), hypoplastic brainstem and normal cerebral hemisphere

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Figure 6: Axial NCCT head showing normal basal ganglia, thalami, lateral ventricles and cerebral hemispheres

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A malformative or a disruptive etiology may be responsible for cerebellar agenesis.[4] Primary cerebellar agenesis is a developmental malformation, whereas in acquired cases, there is disruption of the cerebellum in the prenatal or perinatal period due to hemorrhage, ischemia, or other factors. The acquired causes are usually accompanied by additional brain abnormalities. Recently, mutation of the Ptf1a gene, a key regulator of cerebellar neurogenesis, has been reported in a case of agenesis of the cerebellum.[5] The clinical presentation is highly variable. Cerebellar agenesis has been reported to be associated with profound motor impairment. However, normal or near-normal motor function has also been reported.[1] Our patient also did not have any significant motor impairment. Neuronal plasticity which allows the supratentorial brain to compensate for cerebellar function has been proposed as an explanation. Some cases have shown improvement in motor function over the years,[2] indicating that the remaining brain may compensate for cerebellar function over a period of time. The diagnosis of cerebellar agenesis in living cases is based on MRI scan of the brain. The conventional MRI reveals a normal-sized posterior fossa with cerebrospinal fluid signal intensity. Either no cerebellar tissue or small remnants of the quadrangular lobes may be seen. The tentorial attachment and straight sinus are normally located with no superior displacement. The pons and medulla are hypoplastic due to the lack of afferent input from the cerebellum. Magnetic resonance angiography reveals bilateral absence of the cerebellar vessels.[1] Primary cerebellar agenesis needs to be differentiated from secondary degeneration of the cerebellum in Chiari II malformation and Dandy Walker malformation. Our case illustrates how primary cerebellar agenesis may remain undetectable until adulthood due to the absence of any significant motor abnormalities; however, the entity may present with mild cognitive impairment.

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.
Yu F, Jiang QJ, Sun XY, Zhang RW. A new case of complete primary cerebellar agenesis: Clinical and imaging findings in a living patient. Brain 2015;138(Pt 6):e353.  Back to cited text no. 1
    
2.
Arrigoni F, Romaniello R, Nordio A, Gagliardi C, Borgatti R. Learning to live without the cerebellum. Neuroreport 2015;26:809-13.  Back to cited text no. 2
[PUBMED]    
3.
Mormina E, Briguglio M, Morabito R, Arrigo A, Marino S, Di Rosa G, et al. A rare case of cerebellar agenesis: A probabilistic constrained spherical deconvolution tractographic study. Brain Imaging Behav 2016;10:158-67.  Back to cited text no. 3
[PUBMED]    
4.
Poretti A, Risen S, Meoded A, Northington FJ, Johnston MV, Boltshauser E, et al. Cerebellar agenesis: An extreme form of cerebellar disruption in preterm neonates. J Pediatr Neuroradiol 2013;2:163-7.  Back to cited text no. 4
    
5.
Sellick GS, Barker KT, Stolte-Dijkstra I, Fleischmann C, Coleman RJ, Garrett C, et al. Mutations in PTF1A cause pancreatic and cerebellar agenesis. Nat Genet 2004;36:1301-5.  Back to cited text no. 5
[PUBMED]    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]



 

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