History
The essential criteria for diagnosis of Friedreich ataxia (FA) are progressive limb and gait ataxia developing before the patient is aged 25 years. Ataxia of gait is the most frequent presenting symptom, but this occasionally is preceded by scoliosis or cardiac symptoms.
Difficulty in standing steadily and in running are early symptoms of FA. Children are slow in learning to walk, their gait is clumsy and awkward, and they are not as agile as other children.
Occasionally, it begins rather abruptly following a febrile illness, and one leg may become clumsy before the other.
Although a hemiplegic pattern (ie, the arm and leg on one side become ataxic before those on the other side) has been discussed, it is exceptional; usually, both legs are affected simultaneously.
The hands usually become clumsy months or years after the gait disorder, and dysarthric speech appears after the arms are involved (rarely is it an early symptom).
In some patients with FA, pes cavus and kyphoscoliosis precede the neurologic symptoms. In others, these follow by several years.
Mode of inheritance is autosomal recessive.
Diabetes mellitus occurs in 10% of patients with FA, and an additional 10-20% have impaired glucose tolerance. Most patients with diabetes require insulin therapy, but some achieve reasonable control with oral hypoglycemic drugs. Diabetes tends to cluster within families. Heart disease is present in at least two thirds of patients with FA. Palpitations and angina sometimes occur.
Physical Examination
Patients with very early onset of FA tend to be rather short, but growth and development are normal in those who are ambulant throughout adolescence.
Optic atrophy occurs in approximately 25% of persons with FA. Nystagmus is observed only in approximately 20% of individuals with FA; however, extraocular movements are nearly always abnormal, with broken-up pursuit, dysmetric saccades, square-wave jerks, and failure of fixation and suppression of the vestibuloocular reflex.
Significant sensorineural deafness occurs in 10% of persons with FA.
Heart disease is found in more than 75% of patients. Clinical evidence of ventricular hypertrophy, systolic ejection murmurs, and third or fourth heart sounds may be observed. Signs of heart failure occur late in the disease, often as a preterminal event. This usually is associated with arrhythmias such as atrial fibrillation. Peripheral cyanosis and edema in the lower limbs are very common.
Distal wasting, particularly in the upper limbs, is observed in approximately 50% of patients with FA. Flexor spasms are common. Weakness of the legs is severe in late disease. It rarely involves the arms before the patient is chair bound. Deep tendon reflexes are absent. Plantar responses are extensor in 90% of patients.
Ataxia usually is present at the time of diagnosis.
Loss of vibration and position sense occurs in most persons with established FA. Two-point discrimination may be increased in individuals with early FA.
Sphincter dysfunction, particularly urgency of micturition and constipation, occurs but is not usually severe.
Scoliosis is frequent and may be severe and associated with increased cardiopulmonary morbidity.
Approximately 50% of patients have pes cavus and/or equinovarus deformity of the feet.
Complications
Potential complications of FA include the following:
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Cardiac arrhythmias, angina, heart failure
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Respiratory failure
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Dysphagia
