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Epilepsy Quiz

By:

Dr. Sonia Khan, FRCP (Edin)

Riyadh Military Hospital

 

History: 

A 26 years old right-handed housewife presented with recurrent seizures since the age of 15 years.  The seizures are characterized by an aura of marshing parasthesia of the left arm and face followed by focal clonic jerks of the left arm and left face and occasionally left leg without alteration of consciousness.  At occasions generalized tonic clonic seizures occur.  Postictal left hemiparesis followed the seizures.  The seizures occurred on daily basis with poor response to multiple antiepileptic drugs in monotherapy and polytherapy regimens.  She presented on several occasions to the emergency room in convulsive status epilepticus for which intravenous phenytoin and phenobarbitone are used to abort the seizures.

Past Medical History: Admission to intensive care unit at the age of 10 years in coma after a febrile illness, she remained in hospital for 3 weeks and discharged on no medication.

 

Physical Examination: General examinations are normal.

Systemic Examinations: Normal

 

Nervous System Examinations: Anxious but intact, higher mental function, mild left hemiparesis with power 4/5 and deep tendon hypereflexia and downgoing planter.

Investigations:

Blood investigations – CBC, LFT, U&E, ESR, ANA, Rh factor and viral screen are within normal.

Cerebrospinal Fluid Analysis – Normal

 

Video EEG Monitoring – The patient was monitored on Carbamazipine (CR) 400 mg OD using scalp zygomatic EEG montages.  The patient had 6 stereotyped non-convulsive seizures in the form of left arm and face somatosensory aura (marshing numbness) followed by focal clonic seizure of the left face then left arm with excessive salivation.  The patient remained conscious during the seizure.  Seizure 6 was followed by forced eye and head deviation to the left and generalized tonic clonic seizure.  The ictal EEG onset was right frontocentral regional rhythmic 4-6 Hz in all seizures.  The interictal EEG showed asymmetric EEG background with excessive 5-7 slow transients on the right.

 

MRI Brain

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A-T2 weighted axial image                           B-FLAIR Coronal image

 

 

Interictal FDG PET Scan

A-Interictal FDG PET axial image

A-Interictal FDG PET coronal image

 

Questions:

1.     Describe the MRI findings.

2.     Describe the PET scan findings

3.     What is the epilepsy classification?

4.     What is the likely diagnosis?

Answers:

1.     A. MRI brain: T2 weighted axial image shows mild right hemispheric atrophy.

B. MRI brain: FLAIR coronal image shows hypertensities in the right insular and right mesial temporal regions.  Widening of the right sylvian fissure is noted.

2.     A and B: Interictal FDG PET scans axial and coronal images respectively showing diffuse right temporal lobe and right hemispheric hypometabolism.

3.     The epilepsy classification is right perirolandic epilepsy.

4.     The likely diagnosis is Rasmussen’s encephalitis.

Course of Illness and Management:

After the initial investigations which also included ictal SPECT scan that showed right temporal hyperperfusion, the patient underwent right anterior temporal lobectomy.  After surgery, she continued to have the same habitual seizures and in fact she went into convulsive status epilepticus on the second post operative day.  Histopathology report showed inflammatory changes in the form of perivascular lymphocytic cuffing and gliosis suggestive of focal encephalitis rather than hippocampal sclerosis.  Further investigations performed during the course of the illness including magnetic resonance spectroscopy which confirmed right hemispheric reduction of NAA and elevation of glutamate/glutamine levels.  The diagnosis of late onset Rasmussen encephalitis was made.  Serum antiglutamate receptor 3 antibodies were not raised.  The patient continued to have frequent seizures and several admissions in status epilepticus.  She had progressive left-sided hemiparesis to 2/5 over the following 3 years during which several courses of intravenous immunoglobulin and high dose steroid pulse therapy were given.  The follow-up MRI brain showed progressive atrophy of the right hemisphere.  As the patient continued to have very intractable seizure with repeated convulsive status epilepticus, she was referred for functional hemispherectomy after which the left hemiparesis worsened in the postoperative period.  She was referred to intensive neurorehabilitation.  Currently, she is 2 years post functional hemispherectomy, she has 0/5 power of the left hand but can walk with assistance.  She had no more episodes of the status epilepticus and generalized tonic clonic seizures but occasionally left arm numbness or twitching is noted.  Current antiepileptic medications include Topiramate 100 mg BD.

 

Comments:

The case presentation illustrates several important issues.

 

1.     The concordance of presurgical evaluation data is a prerequisite for successful epilepsy surgery outcome.  In this case although the presurgical evaluation data were lateralizing to the right hemisphere and the MRI showed right mesial temporal sclerosis but the consistent left arm and face somatosensory aura and the early left face and arm clonic seizures were unusual seizure semiology of mesial temporal sclerosis.  The right frontocentral regional ictal EEG onset was also uncommon with mesial temporal sclerosis.  The diffuse right hemispheric hypometabolism on interictal PET scan suggested a neocortical epileptic focus rather than mesial temporal sclerosis.1  The patient eventually received functional hemispherectomy1 which is the recommended surgical treatment in Rasmussen’s syndrome.2

2.     Rasmussen encephalitis is a chronic progressive inflammation of the brain of unknown origin.  The onset is usually in childhood.3 The classical presentation of Rasmussen encephalitis includes an abrupt appearance of focal motor seizures and epilepsia partialis continua which is usually resistant to antiepileptic drugs followed by progressive hemiplegia and cognitive deterioration.3 Our patient had classical presentation of Rasmussen encephalitis but has a delayed age of onset and several cases of late adolescence and adulthood onset cases are reported in the literature. 4

3.     The case also demonstrates the early MRI brain features described in Rasmussen encephalitis that allows early diagnosis.5 The early MRI brain features include focal contralateral white matter hyperintensity with insular cortical atrophy.5 These findings were evident on the early FLAIR images of the patient before the progressive atrophy of the brain became obvious.

 

References:

1.     Imad M Najm, Thomas L Babb, Armin Mohamed, Mesial Temporal Lobe Sclerosis, Epilepsy Surgery. Editor, Hans Luders, 2nd Edition, 2001 by Lippincott Williams and Wilkins, p: 95-103.

2.     Bahi-Buisson N, Nabbout R, Plouin P, Recent Advances in Pathogenic Concepts and Therapeutic Strategies in Rasmussen’s Encephalitis. Rev. Neurol, 2005 April, 161 (4): 395-405.

3.     Granata T, Rasmussen’s Syndrome, Neurological Sciences 2004 Oct, 24 Supp 4: S239-43.

4.     Hunter GR, Donat J, Pryse-Phillips W., Rasmussen’s encephalitis in a 58-year-old female: still a variant, Can J Neurol Sci 2006 Aug, 33 (3): 302-5.

5.     Granata T, Gobbi G, Speafico R, Rasmussen’s encephalitis, early characteristics allow diagnosis, Neurology, 2003, Feb 11, 60 (3): 422-5.