An 18-year-old lady presented with history of progressive swaying while walking, worse in night since 5 years.
Speech was normal and there was not any tremulousness of upper limbs.
Also, there was no history of weakness or numbness.
The family history was significant as her elder sister had similar difficulty in walking of 7-year duration and died because of poorly controlled diabetes mellitus at an age of 20 years.
No other members of the kin were affected and there was no history of consanguinity in the parents.
The cognitive function was normal and her Mini Mental Status Score was 30/30.
Visual acuity and fundus examination were normal.
The extraocular movements including saccades, pursuits were normal, and no saccadic intrusions or nystagmus were noticed.
The tone and power were normal in all four limbs; however, there was generalised exaggeration of myotatic reflexes along with bilateral extensor plantar response.
Vibration and joint position sense were intact but Romberg's was positive.
Patient swayed to either side while performing tandem walk.
Fasting and postprandial blood glucose levels were normal.
Haemogram, renal, liver and thyroid function tests were normal.
Serum vitamin B12 and folic acid levels were within normal limits.
Nerve conduction study showed absent sensory nerve action potential with normal distal latency, conduction velocity and amplitude of compound muscle action potential (CMAP) in all nerves trunks.
MRI showed marked atrophy of the cervical cord as compared to cerebellum which was normal (figure 1).
The genetic testing using PCR disclosed expansion of GAA repeat in both alleles (254 and 298) of FXN gene.
A variety of causes of autosomal recessive ataxias need to be considered in the differential diagnosis of FRDA.
These were systemically excluded here.
Ataxia with vitamin E deficiency (AVED) has a phenotype quite similar to FRDA, though titubation and hyperkinesia are more common in AVED.4 A strong family history of ataxia and diabetes mellitus in elder sister favoured FRDA.
Ataxia with oculomotor apraxia (AOA) types 1 and 2 were not considered owing to lack of apraxia of ocular movements, distal amyotrophy (severe axonal sensorimotor polyneuropathy), atrophy of cerebellum and involuntary movements.5 Ataxia telengiectesia has presentation very similar to AOA types 1 and 2.
Muco-cutaneous markers, sino-pulmonary infections, hypogammaglobulinaemia and radiosensitivity along with predisposition to development of a variety of neoplasms are features of ataxia telengiectasia not seen in AOAs and FRDA.
The other important causes of autosomal recessive spastic ataxia apart from FRDA would be autosomal recessive spastic ataxia of Charlevoix-Saguenay and Marinesco-Sjögren syndrome.
Charcot-Marie-Tooth disease, an inherited polyneuropathy has gait ataxia in common with FRDA; however, in this case, CMT was improbable due to following features in this case: lack of motor weakness, retained reflexes, bilaterally extensor plantar and pure sensory neuropathy on nerve conduction study.
Idebenone was started at a dose of 450 mg twice a day for its antioxidant properties.
For gait ataxia, physiotherapy—Frenkel's exercise—was initiated.
Blood glucose is monitored regularly.
At 4 months, there was no significant change in the gait difficulty.