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Episodic Ataxia: Types, Symptoms And Treatment

Episodic ataxia (EA) is a neurological condition that impairs movement [1] . Although rare, people who are affected by this suffer from episodes of poor coordination and balance (ataxia). These episodes can last from several seconds to several hours. All types of EA are hereditary, however, they are attributed to different genetic causes and also vary in terms of symptoms. The most common ones are Type 1 and Type 2 [2] . Read on to get more information about the various types of EA along with its symptoms and treatment.

What Is Episodic Ataxia (EA)?

EA is an autosomal dominant disorder. It is characterized by sporadic bouts of ataxia with or without continuous muscle movement (myokymia) [1] . EA can be provoked by stress or heavy exertion such as exercise. The symptoms of this illness can first appear in infancy.

EA Type 1: The symptoms of this typically appear in early childhood [3] . The child is likely to have brief bouts of ataxia. Such episodes can occur up to 30 times per day. The following factors can act as the trigger [4] :

  • Caffeine
  • Fatigue
  • Emotional or physical stress

People with Type 1 also report difficulty in speaking along with tremors and muscle weakness during attack episodes. This type is caused by a mutation in the KCNA1 gene [5] . Due to the genetic mutation, signals are disrupted leading to ataxia. The mutation is passed on from a parent to a child.

EA Type 2: It usually appears in childhood or early adulthood. The major characteristic of this is attack episodes that last for several hours [6] . However, these episodes are less frequent when compared to EA Type 1. The following factors can act as triggers [7] :

  • Caffeine
  • Medication
  • Fever
  • Alcohol
  • Stress
  • Physical exertion

People with this condition might also experience double vision, ringing in the ears and difficulty speaking. Repetitive eye movements might occur between attack episodes. In this form of EA, the affected gene is CACNA1A [8] .

Other forms of EA are extremely rare and reports have mostly come up with case studies involving EA Type 1 and Type 2.

Symptoms Of Episodic Ataxia

The symptoms of EA occur in episodes. The symptoms can last for several seconds, minutes or hours. In all types of EA, the primarily noticed symptoms are impaired balance and coordination. The other possible symptoms include the following [9] :

  • Dizziness
  • Blurred vision
  • Involuntary movements
  • Muscle cramps
  • Muscle twitching
  • Muscle spasms
  • Migraine headaches
  • Muscle weakness
  • Nausea
  • Nystagmus (repetitive eye movements)
  • Tinnitus (ringing in the ears)
  • Seizures
  • Vertigo
  • Tremors
  • Slurred speech
  • Hemiplegia (temporary paralysis on one side)

Diagnosis Of Episodic Ataxia

EA is diagnosed using the following tests [10] :

Neurological examination: This would consist of tests that would look into the patient's muscle strength, coordination and memory. It can also include an eye test.

  • Electromyography: This diagnostic procedure assesses the health of muscles and the nerve cells that control them.
  • Genetic testing [11] : This is performed using a sample of blood, hair, skin or tissue.

Before reaching a diagnosis about a rare disorder like EA, the more common causes of ataxia are considered by the doctor. However, if there is a clear family history of ataxia, then genetic testing would ideally be the most opted diagnostic methodology.

When seeking genetic testing [11] , the patient would usually be sent to a genetic counsellor.

Treatment For Episodic Ataxia

Once diagnosed, EA is ideally treated with anticonvulsant or antiseizure medication [12] . The most commonly used drug for the treatment of EA Type 1 and 2 is acetazolamide [13] . Other medications include the following:

  • Carbamazepine
  • Valproic acid
  • Flunarizine
  • Dalfampridine

Additional drugs may be prescribed to treat other symptoms of EA. Some doctors recommend physical therapy alongside medication to improve mobility. Diet and lifestyle changes can help in avoiding triggers. However, one must go through strict clinical trials to improve treatment options.

On A Final Note...

There is no cure for EA. Although it is a chronic condition, research says that it does not affect one's life expectancy. In some rare cases, with time, the symptoms might just go away on their own. However, when symptoms persist, treatment methodologies can be put into use to ease them.

View Article References
  1. [1] Choi, K. D., & Choi, J. H. (2016). Episodic Ataxias: Clinical and Genetic Features.Journal of movement disorders,9(3), 129–135.
  2. [2] Ophoff, R. A., Terwindt, G. M., Vergouwe, M. N., Van Eijk, R., Oefner, P. J., Hoffman, S. M., ... & Haan, J. (1996). Familial hemiplegic migraine and episodic ataxia type-2 are caused by mutations in the Ca2+ channel gene CACNL1A4.Cell,87(3), 543-552.
  3. [3] Zuberi, S. M., Eunson, L. H., Spauschus, A., De Silva, R., Tolmie, J., Wood, N. W., ... & Hanna, M. G. (1999). A novel mutation in the human voltage-gated potassium channel gene (Kv1. 1) associates with episodic ataxia type 1 and sometimes with partial epilepsy.Brain,122(5), 817-825.
  4. [4] Rajakulendran, S., Schorge, S., Kullmann, D. M., & Hanna, M. G. (2007). Episodic ataxia type 1: a neuronal potassium channelopathy.Neurotherapeutics,4(2), 258-266.
  5. [5] Imbrici, P., D'Adamo, M. C., Kullmann, D. M., & Pessia, M. (2006). Episodic ataxia type 1 mutations in the KCNA1 gene impair the fast inactivation properties of the human potassium channels Kv1. 4‐1.1/Kvβ1. 1 and Kv1. 4‐1.1/Kvβ1. 2.European Journal of Neuroscience,24(11), 3073-3083.
  6. [6] Jodice, C., Mantuano, E., Veneziano, L., Trettel, F., Sabbadini, G., Calandriello, L., ... & Ophoff, R. A. (1997). Episodic ataxia type 2 (EA2) and spinocerebellar ataxia type 6 (SCA6) due to CAG repeat expansion in the CACNA1A gene on chromosome 19p.Human molecular genetics,6(11), 1973-1978.
  7. [7] Strupp, M., Zwergal, A., & Brandt, T. (2007). Episodic ataxia type 2.Neurotherapeutics,4(2), 267-273.
  8. [8] Guida, S., Trettel, F., Pagnutti, S., Mantuano, E., Tottene, A., Veneziano, L., ... & Volsen, S. (2001). Complete loss of P/Q calcium channel activity caused by a CACNA1A missense mutation carried by patients with episodic ataxia type 2.The American Journal of Human Genetics,68(3), 759-764.
  9. [9] Gancher, S. T., & Nutt, J. G. (1986). Autosomal dominant episodic ataxia: a heterogeneous syndrome.Movement disorders: official journal of the Movement Disorder Society,1(4), 239-253.
  10. [10] Jen, J. C., Graves, T. D., Hess, E. J., Hanna, M. G., Griggs, R. C., Baloh, R. W., & CINCH investigators. (2007). Primary episodic ataxias: diagnosis, pathogenesis and treatment.Brain,130(10), 2484-2493.
  11. [11] Labrum, R. W., Rajakulendran, S., Graves, T. D., Eunson, L. H., Bevan, R., Sweeney, M. G., ... & Ostergaard, J. R. (2009). Large scale calcium channel gene rearrangements in episodic ataxia and hemiplegic migraine: implications for diagnostic testing.Journal of medical genetics,46(11), 786-791.
  12. [12] Rogawski, M. A., & Löscher, W. (2004). The neurobiology of antiepileptic drugs for the treatment of nonepileptic conditions.Nature medicine,10(7), 685.
  13. [13] Zasorin, N. L., Baloh, R. W., & Myers, L. B. (1983). Acetazolamide‐responsive episodic ataxia syndrome.Neurology,33(9), 1212-1212.

Read more about: mental movement genetic hereditary
Story first published: Saturday, June 8, 2019, 9:00 [IST]
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