|Year : 2010 | Volume
| Issue : 4 | Page : 648--650
Sporadic hemiplegic migraine in children: A report of two new cases
A Chakravarty, A Sen
Department of Neurology, Vivekananda Institute of Medical Sciences, Kolkata, India
1E 1202, Avishikta II, Kolkata-700 078
Two cases of sporadic hemiplegic migraine, which fulfilled the diagnostic criteria as laid down in International Classification of Headache Disorders (ICHD)-2, are reported in children. In the first case, two unusual features were noted, namely, the occurrence of dysphsia in association with a left hemiparesis and the spread of sensory symptoms to the contralateral side during attacks. The second case is perhaps the youngest patient reported with this disorder.
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Chakravarty A, Sen A. Sporadic hemiplegic migraine in children: A report of two new cases.Neurol India 2010;58:648-650
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Chakravarty A, Sen A. Sporadic hemiplegic migraine in children: A report of two new cases. Neurol India [serial online] 2010 [cited 2020 Sep 26 ];58:648-650
Available from: http://www.neurologyindia.com/text.asp?2010/58/4/648/68694
The International headache Society classifies hemiplegic migraine (HM) under the common rubric of migraine with aura (1.2).  HM occurs in two forms: familial (FHM 1.2.4) and sporadic (SHM 1.2.5). Onset is generally in childhood and attacks cease by adult age. Both forms share a similar spectrum of clinical presentations and genetic heterogeneity. Current data support the concept that sporadic and familial cases should be thought of as similar but separate disorders. FHM is the only migraine subtype for which a monogenic mode of inheritance (autosomal dominant) has been clearly established. Sporadic cases are more difficult to diagnose and often require several investigations to rule out more sinister possibilities. FHM is known to be caused by mutations in either of the following three gene loci - CACNA1A, ATP1A2 and SCN 1A. Some recent studies have identified involvement of these gene loci is SHM as well. , Moskowitz et al. have suggested that FHM mutations render the brain more susceptible to prolonged cortical spreading depression (CSD) caused by either excessive synaptic glutamate release or decreased removal of glutamate and K + from the synaptic cleft. Certainly, there is reduced threshold to initiation of CSD in a mouse model of FHM. 
Similar to FHM, the phenotype of SHM attacks may include fever, lethargy, dysphasias, confusion, hemiparesis, hemisensory symptoms, hemianopia and scintillating scotoma. The symptomatology often resembles those of a stroke. SHM has been recently reviewed by Thomsen and Olesen.  From a pathophysiological point of view, it is unclear whether SHM reflects severe attacks of typical migraine with aura that just includes motor symptoms in addition to the well-known visual, sensory and speech symptoms or it represents a separate type of migraine with aura. We report here two cases of sporadic hemiplegic migraine (SHM) in children, one of whom had some unusual features.
A 14-year-old right-handed girl presented in July 2008 after she had three attacks of left-sided sensory disturbances associated with right hemicranial headaches. The attacks occurred at a few days interval when she first got numbness and tingling on the left side of the face and arm spreading down to involve the left side of the body and then the left leg. By the time the sensation spread to the leg, she became unable to speak and write with her right hand though comprehension remained intact for both spoken and written commands. Her speech was not slurred according to her parents. She was unable to bring out the appropriate words and could only utter some meaningless sounds. Even she could not express her thoughts through gestures. Neither her reading ability nor her praxis during the attacks, were tested by her parents as they were so terrified. Associated with the development of left-sided numbness, she developed weakness of left hand grip and difficulty in walking. The paresthesia affecting her left limbs, by this time, got spread to involve the right foot and leg as well. She never experienced any visual phenomenon and the numbness, weakness and speech difficulty resolved in about 45 minutes. These motor and sensory symptoms were always followed by development of throbbing right hemicranial headaches with nausea and photophobia lasting several hours. In between attacks, her neurological examination was normal; there was no residual weakness, speech problem or ataxia. Tested later on a computer version of Edinburgh Handedness Inventory ( http://www.google.com ), it was found that she was a clear right-handed person. She had no past history of having had migraine headaches and no one in her family was affected with a similar disorder. However, her mother had migraine attacks without aura. Full hematological profile including coagulation screening was negative. She had a normal contrast enhanced magnetic resonance (MR) brain scan and normal MR angiography of brain and cervical arteries. Electroencephalography (EEG), electrocardiography (ECG) and trans-esophageal echocardiography were normal. Molecular genetic studies could not be done as facilities were not available.
She was kept under follow up and had no recurrence of spells after she was started on Topiramate 50 mg twice daily. The choice of prophylactic drug had been somewhat arbitrary but Valproate had been avoided because of her sex and age and there may be theoretical arguments against use of beta blockers in HM. She is now under follow up for over 18 months without any recurrence of any neurological problem.
A 2-year-old male child was referred in July 2009 from the Pediatrics Department, for assessment. He had three episodes of transient left-sided weakness with facial deviation occurring over the preceding 2 months prior to referral. There had been no alteration in his sensorium during or following these episodes. There were no seizures. The episodic weakness lasted for 3-4 days, followed by complete recovery. He was assessed by pediatricians and he had no neurological deficit in between attacks. He had no cranial or cervical bruits and no heart murmurs.
The attacks, on all occasions, were preceded by one or two spells of vomiting when the child appeared a bit restless and was noted to rub his head with both hands. These continued for about an hour before limb paralysis set in.
The child was born at full term through normal delivery and cried at birth. His developmental milestones were normal.
There was no history of similar disorder or epilepsy in the family. However, his mother and maternal aunt suffered from migraine without aura.
The child was extensively investigated. These included cerebrospinal fluid (CSF) study (during one attack of limb paralysis), coagulation profile, serum lipids, sickling test, serum lactate and pyruvate and plasma homocystine level. All reports were normal. His contrast-enhanced MR brain imaging, MR brain angiography and venography were also normal. Trans-thoracic echocardiography and Doppler evaluation of neck arteries revealed no abnormality. A 6-hour video EEG was normal. No molecular genetic study was performed as facilities were not available. Diagnosis of SHM was essentially clinical and by exclusion of other possibilities, as far as practicable in our set up. The clinical features fulfilled the diagnostic criterion of SHM in ICHD-2. The child was treated with Cyproheptidine and no recurrence has been reported yet (follow up 5 months). Other migraine prophylactic agents were avoided basically because of the age, and anti-epileptics were not prescribed to avoid any diagnostic confusion with epilepsy.
Both the cases fulfilled the diagnostic criteria of SHM (1.2.5) of the International Headache Society (ICHD-2)  and the first case is perhaps the second case of SHM to be reported from India.  Structural brain lesions including congenital and vascular anomalies were excluded by imaging studies in both. Alternating hemiplegia in childhood (AHC) was considered in the differential diagnosis in both the cases but seemed unlikely as in AHC there is infantile onset and there is high prevalence of associated neurological abnormalities which become increasingly obvious with age. However, a recent study had mentioned some genetic overlap between AHC and FHM.  A mitochondrial cytopathy was seriously considered in the differential diagnosis in the second case, but seemed unlikely in view of the clinical history, normal neuroimaging and normal lactate/pyruvate ratio.
Case 1 exhibited two unusual features: the development of dysphasia and writing disturbance with left hemisensory phenomenon and hemiparesis in a right-handed person and the spread of the sensory symptoms from left to the right lower limb during attacks. The dysphasia was of the anterior or non-fluent type due to affection of left Broca's area. Both these features suggest bilateral hemispheric involvement in this girl by the spreading cortical depression of migraine.
In this case, the temporal evolution of symptoms clearly indicated a phenomenon of spreading continuity in the cerebral cortex so characteristic of CSD. The unusual feature is the absence of visual aura (previously reported to occur in all cases of SHM  ), as CSD is generally thought to begin in the occipital cortex. CSD, of course, is yet to be clearly demonstrated to occur in migraines other than migraine with typical aura. A probable major point of difference between SHM and migraine with typical aura is that the threshold for CSD is lowered less in SHM than the latter but once started, the spread is more rapid and restorative processes more affected, taking a longer time to recover (as evident from durations of aura symptoms in both cases 1 and 2).
With bihemispheric involvement in this girl, a clinical question regarding the possibility of Basilar Migraine would arise. In fact, as stated by Thomsen and Olesen,  72% of SHM patients fulfill the IHS diagnostic criteria for Basilar Migraine. However, leaving aside the debatable issues in diagnostic criteria, on clinical grounds, the absence of visual symptoms and other brain stem features like vertigo, dysarthria (the girl was dysphasic), diplopia and ataxia would clinch the diagnosis of SHM in case 1. This view is shared by Thomsen and Olesen  as well.
Case 2 is perhaps the youngest patient with SHM reported so far. As mentioned earlier, in the absence of genetic study, diagnosis had been essentially clinical. A major differential diagnosis in case 2 remains some form of a partial seizure. Rubbing of head with both hands before development of motor weakness should not be considered a seizure automatism (as this has no localizing value); rather it suggests the presence of head pain that the child most likely had. The borderland between epilepsy and migraine often remains hazy even after investigations. The diagnostic criterion for SHM, as laid down in ICHD-2,  is essentially clinical.
AHC would be a closer mimic in case 2. Early workers considered AHC to be rare form of complicated migraine.  The current status remains undetermined in ICHD-2. However, the points against considering this diagnosis in Case 2 are that AHC is often associated with neurodegenerative diseases and onset is always below 18 months.  Several months of follow up of the case has not revealed any new neurological problems nor any recurrence of hemiplegias.
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