Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Friedreich Ataxia

Basics
Description
  • Friedreich ataxia is an uncommon, heritable disorder causing progressive spinocerebellar degeneration.
  • Scoliosis, ataxia, and foot deformities are the most common findings.
  • Systems affected: Central nervous system; Heart; Skeleton
  • Classification:
    • No subclassifications are used in Friedreich ataxia.
    • It is classified under the category spinocerebellar degeneration, and it is the most common example of this class.
    • Another disorder in this class is spinocerebellar ataxia.
  • Synonym: Spinocerebellar degeneration
Epidemiology
Incidence
Prevalence is ~1 per 50,000 persons.
 
Prevalence
  • It may become apparent anytime from 5-25 years of age.
  • Males and females are affected equally.
Risk Factors
The condition is more common in people of French Canadian descent.
 
Genetics
Transmission is autosomal recessive.
 
Etiology
  • The cause is a defect in a gene for a protein, frataxin, found on chromosome 9.
  • The pathogenesis of the findings is not well known.
  • Variations in characteristics of the disease (e.g., age at onset and rate of progression) may be caused by different mutations at one of the loci.
Associated Conditions
  • Diabetes mellitus
  • Cardiomyopathy
  • Scoliosis
  • Foot deformity
Diagnosis
The diagnosis is made on a clinical basis, usually confirmed by a neurologist.
 
Signs and Symptoms
  • Common signs:
    • Ataxia
    • Wide-based gait
    • Weakness and loss of position sense in the lower extremities
    • Frequently, loss of upper extremity reflexes
  • Less common signs:
    • Pes cavus
    • Optic atrophy
    • Nystagmus is possible.
  • Symptoms:
    • Partial deafness, depression, loss of coordination, painful muscle spasms, and weakness
    • Symptoms of diabetes mellitus also may be related because of the increased coexistence of these disorders.
Physical Exam
  • Examine heel-to-toe walking and finger-to-nose positioning.
  • Look for the presence of increased kyphosis on routine standing.
  • Perform the forward-bend test for scoliosis.
  • Test upper and lower extremity reflexes.
  • Note the flexibility of the feet and the correctability of any deformity.
  • Test muscle strength (proximal muscles are affected earlier are than distal muscles).
  • The gluteus maximus is the 1st muscle to be affected clinically.
Tests
Lab
  • Creatine phosphokinase levels are normal.
  • Fasting serum glucose for diabetes mellitus should be obtained.
  • Other tests:
    • Electrocardiography should be performed before surgery, with echocardiography as indicated, because of the increased incidence of hypertrophic cardiomyopathy.
    • Electromyography shows polyphasic potentials and mild slowing of nerve conduction velocity.
Imaging
  • Standing posteroanterior and lateral radiographs of the spine should be ordered when scoliosis and kyphosis are found.
    • Periodic monitoring then is indicated, even after maturity.
  • Foot radiographs may be indicated.
Differential Diagnosis
  • Cerebellar tumors
  • Chiari malformation
  • Muscular dystrophy
  • Spinal dysraphism (as a cause of scoliosis and foot deformity)
Treatment
General Measures
  • Foot and spine deformities should be followed by an orthopaedic surgeon, even if surgery is not contemplated.
  • Brace treatment of scoliosis is appropriate for curves of 25-45° and may slow the rate of progression.
  • Stretching and night bracing may be helpful in preventing worsening of the foot deformities.
  • Walking should be maintained as long as possible.
Special Therapy
Physical Therapy
  • Therapy is essential, to keep up strength and skills after surgery.
  • Stretching of plantar fascia and ankle muscles help to prevent deformity.
Medication
  • No medical treatment currently is available.
  • If painful muscle spasms occur, baclofen or diazepam may be helpful.
Surgery
  • Scoliosis:
    • A cardiopulmonary evaluation is indicated preoperatively.
    • To prevent progressive decompensation of the spine, posterior fusion and instrumentation with 2 contoured rods is indicated for curves of >50°.
    • If the curve is large, rigid, and unbalanced, an anterior release also may be indicated to increase the correctability.
    • Spinal cord monitoring may be more challenging and should include sensory and motor modalities.
    • Postoperative immobilization usually is unnecessary.
  • Cavovarus feet: Correction may include:
    • Plantar fasciotomy
    • Achilles tendon lengthening and transfer or lengthening of the PTT
    • Possible osteotomy
Follow-up
Disposition
Issues for Referral
A neurologist is the best specialist for coordinating the overall care of these patients.
 
Prognosis
  • If scoliosis develops before the patient is 15 years old, it most likely will become severe and require surgery.
  • Most affected individuals stop walking by 20-30 years of age and are wheelchair dependent.
  • Death usually occurs by the 4th or 5th decade; causes most often include pneumonia, aspiration, and cardiomyopathy.
Complications
  • Cardiomyopathy
  • Calluses or skin breakdown on the foot
  • Pneumonia
Patient Monitoring
  • This disease is progressive.
  • Walking distance and status of all physical findings should be monitored every 3-6 months.
  • Scoliosis, if present, should be checked every 6 months.
Miscellaneous
Codes
ICD9-CM
334.0 Friedreich ataxia
 
Patient Teaching
  • Patients should be counseled about the natural history of the disease, which consists of slow degeneration, so they can plan appropriately.
  • Patient support groups often are helpful.
  • Genetic counseling should be offered.
FAQ
Q: Will physical therapy help to restore coordination?
A: No. Coordination depends most on the progression of the disease.

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