[MIM 104 290, 614 820]

Very rare: incidence estimated at 1/100,000. Association of periodic hemiplegia, paroxysmal disorders and cognitive impairment. The precise etiology is not yet known : autosomal dominant transmission of mutations of the .ATP1A3 (19q13.2) (75 %) ou ATP1A2 (1q23.2) have been identified.

Cases associated with a mutation of the ATP1A3 gene are more severe: they lead to dysfunction of the a3 subunit of the neuronal Na/K ATPase. This causes cortical hyperexcitability that can lead to seizures and spread to some nuclei in the brainstem (apnea). Other mutations of the ATP1A3 gene cause CAPOS syndrome and type 12 dystonia (see these terms).

Clinical presentation:

-        onset before 18 months of age, typically before 6 months of age with paroxysmal nystagmus, dystonia or tonic attacks

-        bouts of hemiplegia: flaccid paralysis of variable intensity and location during the same episode. The face is usually spared and consciousness remains intact; sleep has a remedial  effect on hemiplegia, and the effect can last up to 10 to 20 minutes after waking up

-        dystonic posturing: stiffness of one or several limbs, often accompanied by a shaking tremor; choreoathetosis

-        autonomic manifestations: vasomotor and cardiorespiratory disorders: bradycardia, stridor, apneas, oropharyngeal dystonia (risk of laryngeal dyskinesia)

-        short QT ( <370 msec) with risk of cardiac rhythm disorders, mostly in case of mutation of the ATP1A3

-        central apneas and/or obstructive sleep apneas)

-        headache

-        epileptic seizures in 18 to 59 % of the cases

-        delayed motor development: hypotonia, ataxic gait; difficulty performing fine gestures

-        psychomotor and cognitive retardation, speech disorders

-        secundary mitochondrial dysfunction

Paroxysmal episodes can be triggered by stress, changes in light intensity, exposure to water or by some food.

Treatment: only flunarizine (a calcium-blocking agent) seems to decrease the attacks of hemiplegia; antiepileptic drugs.

Anesthetic implications: 

epileptic patient; developmental retardation; preoperative ECG: bradycardia ? short QT ?increased risk of perianesthetic complications: seizures, apneas, cardiac rhythm disorders

References : 

• Mehrotra R.
  General anesthesia for a patient with alternating hemiplegia of childhood.
  Can J Anaesth 2005 ; 52 :1103-4
• Panagiotakaki E, Arzimanoglou A.
  L’hémiplégie alternante du nourrisson à l’âge adulte.
  Neurologies 2011 ; 14 : 83-7.
• Funk EM, Mikati MA, Landstrom AP, Moya-Mendez ME, Wallace KR, Pratt MO, Heyes ME, Dear G.
  Anesthetic implications in alternating hemiplegia of childhood: a case report.
  ANA Journal 2002;11: 317-20. doi:10.1054/ijoa.2002.0986
• Parker LE, Wallace K, Thevathasan Z, Funk E, Pratt M, Thamby J et al. 
  Characterization of sedation and anesthesia complications in patients with alternating hemiplegia of childhood.
  Eur J Paediatr Neurol 2022 ; 38 : 47–52

Updated: November 2022