Introduction
Meaning of Ataxia: a - not, without; taxis - arrangement, order
Ataxia is a term used to describe muscle incoordination leading to lack of precision of movement and the inability to maintain balance.
This manifests as problems with walking, sitting, carrying out fine movements, difficulties with speech, swallowing, and nystagmus.
The most prominent feature is an abnormal gait - which is wide-based, lurching, and staggering, commonly called ‘drunken man gait’.
Gait dysfunction, incoordination of limb movement due to muscle weakness is not ataxia.
Ataxia is not only due to cerebellar causes. Pathological changes in its connections to the cortex, brainstem, basal ganglia for example, can cause ataxia.
Ataxia Types
Ataxia is broadly divided into 3 types: Cerebellar, Vestibular and Sensory
Sensory Ataxia:
- Localisation: It is due to loss of sensory input to the cerebellum because of peripheral nerve or posterior column disease.
- Clinical features: Along with incoordination and wide-based gait, position and vibration sense is also impaired.
- The patient often looks at the feet to know their position in space.
- The patient has a high stepping gait and imbalance on standing/walking with eyes closed. . (Positive Rhomberg's test).
- The speech is invariably normal.
- Sensory ataxia is seen with B12 deficiency, Miller-Fisher syndrome
- Clinical Clue: ask if patient needs to switch on the light when walking to the toilet at night.
Vestibular Ataxia
Disorders of the vestibular system (inner ear apparatus, vestibulocochlear nerve, vestibular nucleus) cause ataxia, vertigo, and nystagmus.
Presence of additional neurological features, severe nausea, and vomiting, hearing loss point towards a peripheral cause. Severe ataxia and nystagmus that change with a change in gaze direction indicates a central cause.
Children may not be able to communicate symptoms of dizziness, tinnitus. Therefore a full neurological exam is essential. Some causes of vestibular ataxia in children include acute labrynthitis, migraine headache.
Benign Paroxysmal Vertigo of Childhood(BPVC):
Occurs in children under the age of four years. There are sudden, recurrent episodes of vertigo, loss of balance, with autonomic features of pallor, sweating, fearfulness.
Events last for about one minute.
Treatment is supportive, episodes resolve by age of 10. Though an uncommon condition, symptoms of BPVC are quite dramatic, prompting an urgent visit to the doctor.
Cerebellar Ataxia:
Key features of cerebellar ataxia:
- Truncal Ataxia:
Clinical features: The child has trouble keeping balance even while sitting with worsening when asked to sit with legs crossed.
- Gait ataxia:
Clinical features: This ataxia is better revealed on standing/running. The child has even more trouble keeping balance with eyes open. The gait is more lurching than seen in sensory ataxia (its almost staggering as seen in acute alcohol intoxication) and is more apparent when the patient is asked to turn quickly or hop on one foot.
On history: Child falls while walking/running.
Localisation:
In the case of truncal ataxia, the lesion is in the vermis of the cerebellum.
Ataxia with disturbance predominant in one direction and dysmetria and hypotonia in unilateral limbs is seen in lesions in the ipsilateral cerebellar hemispheres.
There is a tendency to veer off in the direction of the affected hemisphere.
- Dysmetria - inability to control the speed, precision, and range of motion while carrying out a voluntary activity. Elicited by finger-to-nose test, heel-to-shin test.
On history: child is clumsy, handwriting, coloring is not as good as before.
- Intention tremor - rhythmic, high amplitude tremors seen in distal extremity. The tremors become prominent while reaching the end of the target.
Bobbing of the head, called titubation, may also be seen due to slow frequency tremors of the head and axial hypotonia.
On history: Child overshoots/ undershoots while trying to grab a toy, parent feels the child is clumsy. Parents note to-and-fro movement of the head when child is sitting up.
On exam: Elicited by finger-to-nose test, reaching out to grab an object. Ask child to pick up a small object, like a button, with two fingers to elicit the tremor.
Caveat: Titubation as an isolated feature - Rule out lesions of the third ventricle, periventricular lesions.
- Dysdiadochokinesia - type of dysmetria. It is the inability to perform rapid, alternating movements.
On exam: Elicited by performing finger-to-nose test, pronation-supination of hand, foot tapping.
- Dysarthria - Change in pitch, loudness, and articulation. Speech sounds monotonous, with a breakdown of words into separate syllables - called scanning speech.
- Nystagmus - involuntary, oscillatory eye movements with fast phase towards the site of the lesion.
- Hypotonia - low muscle tone is seen and joints appear more mobile.
On exam: Pendular reflex - swinging of the limb to and from neutral position more than 3 times is seen(Swinging once to and once from neutral is normal). Elicited while testing the triceps and patellar reflexes.
Acute Ataxia
- Drugs and toxins
- Immune mediated
- Acute cerebellar ataxia
- Acute cerebellitis
- Miller Fisher syndrome
- Multiple sclerosis
- Opsoclonus-myoclonus Ataxia syndrome (OMA/OMS)
- Brain Stem Encephalitis (limbic encephalitis)
- Trauma
- Space occupying lesion - tumor, abscess in the posterior cranial fossa
- Acute hemorrhage into Brain Tumor
- Vascular Disease - ischemic or hemorrhagic stroke involving vertobasilar circulation
- Vertebrobasilar migraine
- Genetic and Metabolic Disorders
- Pseudoataxia/ epileptic ataxia
- Psychogenic ataxia - astasia-abasia
Acute ataxia - presentation is with acute onset of dizziness, nausea, and vomiting followed by nystagmus, intention tremor, imbalance, and staggering gait. In case of post-infectious etiology, there may be a history of viral prodrome a few days to 2-3 weeks prior to onset of symptoms.
Acute Ataxia with Rapid Improvement
The two commonest causes are:
Drug Ingestion
Acute cerebellar ataxia following a viral illness
Drug Ingestion:
Accidental drug ingestion is highest between 1 and 4 years of age. Ingestion of hypnotics, tranquilizers, toxic doses of anticonvulsants, especially phenytoin and carbamazepine may cause ataxia.
Phenytoin toxicity:
Phenytoin has a narrow therapeutic window (10-20 mcg/ml) and follows zero order kinetics. It is extensively protein bound and has several drug interactions. These factors make phenytoin toxicity more likely, as compared to other anticonvulsants.
Purkinje cell toxicity has been found to be an vitro cause of phenytoin toxicity.
If a child is on a high dose of phenytoin, it usually takes 5-10 days for the ataxia to develop and about the same time after stopping or reducing the dose for the symptoms to disappear.
Clinical features of toxicity include nausea, vomiting, ataxia, and nystagmus. Nystagmus is initially seen on lateral gaze, eventually may become alternating, or bidirectional. Symptoms of CNS depression and paradoxical seizures are seen at higher doses.
Diagnosis is confirmed on checking phenytoin levels. Free and total phenytoin levels should be checked, especially in patients with low protein levels - malnutrition, renal and liver disease, several medications that may displace phenytoin.
Treatment includes reducing or totally stopping phenytoin and supportive measures. Seizures may be treated with benzodiazepines.
Other toxins/medications:
Acute intoxication with glue, solvents, petrol, alcohol, antihistamines may also cause ataxia.
It is diagnosed on the basis of history and urine examination for drug metabolites and blood for toxic analysis.
Acute cerebellar ataxia:
- It is usually seen in children between 2 to 7 years of age.
- It is often preceded by an exanthema (varicella), infectious mononucleosis, or other viral infections (polio, mumps, coxsackie, herpes, simplex, or ECHO viruses).
- It is thought to occur due to an autoimmune response to the viral agent.
- It has also been reported after vaccine administration.
- Ataxia is maximum at the onset.
- Symptoms are non-progressive for a couple of days or weeks and then subside. (Recovery may take 3 weeks to 5 months).
- Neuroimaging is normal.
- Recovery is usually complete.
- It is a diagnosis of exclusion.
- Tendon reflexes are usually present (absence may suggest Miller Fisher syndrome).
- It is a benign, self-limiting condition, and treatment is usually not required.
Acute Cerebellitis:
- Acute cerebellar ataxia should be differentiated from acute cerebellitis, which is a serious, life-threatening condition.
- Presentation is similar with additional neurological signs such as altered mental status, headache.
- Neuroimaging shows uni/bilateral T2/Flair hyperintensities in the cerebellum with variable enhancement.
- Signs of raised intracranial pressure and subsequent herniation are seen in severe cases. -Steroids are used to reduce the inflammation.
Acute disseminated encephalomeyelitis (ADEM):
It may also present with cerebellar features, in addition to other neurological symptoms. Imaging helps in confirming the diagnosis.
Acute Ataxia with Prolonged or Intermittent Course
The commonest conditions to keep in mind are:
- Opsoclonus-Myoclonus Ataxia syndrome (OMA/OMS)
- Brain Tumors
- Multiple sclerosis
- Metabolic disorders presenting with ataxia
- Episodic ataxias
OMA/OMS:
- Also known as ‘dancing etes, dancing feet’ syndrome/Kinsbourne Syndrome/ Myoclonic encephalopathy of infancy
- It is a neuroinflammatory disorder seen in the toddler age group, but described in infants and older children as well.
- Approximately half the cases have a history of a febrile illness (post-infectious etiology) and the remainder are associated with a neural crest tumor, most commonly, neuroblastoma.
- Clinical presentation is typically an acute-subacute onset of frequent falls, unsteady gait in a previously healthy child. This is due to jitteriness - low amplitude myoclonus of the limbs that leads to loss of balance, clumsiness. In addition, chaotic, non rhythmic eye movements called opsoclonus are seen.
- A marked characteristic of OMA is the presence of irritability, behavioral changes, loss of milestones.
- Though rare, OMA should be suspected in every young child presenting with ataxia and behavioral changes.
- Opsoclonus may not be present at clinical presentation, making diagnosis difficult.
- Workup includes PET scan, contrast enhanced CT scan to look for the tumor.
- MIBG scan, urine catecholamine testing have high incidence of false negatives and should be ordered and interpreted with caution.
- Treatment includes one to several rounds of multimodal immunosuppressive therapy - ACTH/steroids, Rituximab and IvIg. Tumor removal alone is rarely sufficient.
- Though there may be near complete resolution of symptoms in most cases, residual neurological sequelae, cognitive and developmental concerns are seen quite frequently. -Timely diagnosis and therapy increase the chances of symptomatic improvement.
Brain Tumors:
Brain tumors generally present insidiously with headache, vomiting, focal neurological deficits. However, sudden bleeding into the tumor or acute development of hydrocephalus may cause acute ataxia. Diagnosis is confirmed by neuro-imaging.
Multiple Sclerosis (MS):
- It is an auto-immune disorder characterized by recurrent episodes of non-contiguous demyelination of the brain, spinal cord, and optic nerves.
- It is seen in children in the peri-pubertal age group and older adolescents. It is commonly seen in females and may present as an attack of optic or retrobulbar neuritis, ataxia, and focal neurological deficits.
- The diagnosis of multiple sclerosis can be established only after the patient has had at least two separate onset of symptoms with different localization, with evidence of demyelination in separate areas of the brain spinal cord and/or optic nerve, with the symptoms occurring at different points in time, often separated by months or years.
- The spectrum of demyelinating disorders has further expanded to include demyelination with myelin oligodendrocyte glycoprotein antibodies (MOG-IgG) and Neuromyelits Optica (Devic’s disease) with the presence of aquaporin-4 Antibodies (AQP-4 IgG).
- CSF studies may show increased protein, the presence of oligoclonal bands. -Neuroimaging is essential to look for evidence of demyelination and rule out other disorders as well as for monitoring treatment.
- Management includes intravenous corticosteroids or plasma exchange for acute episodes. -Long-term treatment includes immunosuppressive agents such as Rituximab, azathioprine and mycophenolate mofetil.
- Long term outcome is unpredictable with cognitive and neurological deficits seen frequently.
Episodic Ataxias
There are recurrent episodes of sudden onset ataxia, lasting for minutes to several hours. Several subtypes have been described. Ataxia may become constant in advanced disease.
EA1 - KCNA1 gene mutation with autosomal dominant inheritance.
- Myokymia(rippling of muscle) is present constantly.
- In addition to ataxia, variable clinical features may be present - stiffening of limbs, dysarthria, headache, etc. lasting for seconds to minutes.
- Events may be triggered by emotional or physical stress.
- There is inconsistent response to Acetazolamide and anti-epileptics.
EA2 - Caused by a mutation in the CACNA1A gene.
- Has autosomal dominant inheritance.
- EA2 is the most common episodic ataxia syndrome.
- Episodes last hours to days and are triggered by sudden movement, stress.
- Nystagmus and vertigo are frequently seen with ataxia.
- The episodes show a good response to acetazolamide.
Metabolic disorders presenting with ataxia:
Several metabolic disorders can present with ataxia. Though they are rare, it is important to suspect and workup for metabolic ataxia as the condition maybe life-threatening if left untreated, and also because some of them have specific treatment.
For eg. high dose riboflavin for Riboflavin transporter deficiency, Ketogenic diet in case of GLUT1 deficiency.
Metabolic ataxia should be suspected when
- Acute onset of ataxia with preceded by illness or fasting
- History of consanguinity
- Neuroregression,
- Abnormal exam - eg. coarse features and organomegaly in lysosomal storage disorders, microcephaly and paroxysmal movement disorder in GLUT1 deficiency
- Abnormal Brain MRI
- Unexplained acidosis, hyperammonemia
Epilepsy and Ataxia:
- Non - convulsive or subclinical seizures can present with ataxia. For example, absence epilepsy can present with absence status epilepticus which has prolonged periods of confusion, eye blinking, unsteady gait. Treatment is with intravenous benzodiazepines.
- Ataxia can also occur as a side effect of anti-seizure medication.
- Progressive myoclonic epilepsies, Subacute Sclerosing Pan- Encpehaltis (SSPE) present with ataxia, seizures and cognitive decline.
Astasia- Abasia: It is defined as a condition with impaired ability to stand and walk. Though it is considered being a type of conversion disorder (psychogenic cause), lesions in the basal ganglia, frontal lobe may cause astasia-abasia as well. In children, diagnosis of psychogenic gait disturbances should be made with caution.
Ataxia with Insidious Onset (Chronic Ataxias)
Differential diagnosis of a child with chronic or progressive ataxia:
- BRAIN TUMORS
- Cerebellar astrocytoma
- Cerebellar hemangioblastoma
- Ependymoma
- Medulloblastoma
- Supratentorial tumors
- HEREDITARY ATAXIAS
- Autosomal recessive inheritance
- Autosomal dominant inheritance
- X-linked inheritance
- Spastic ataxias
- Ataxia with mitochondrial disorders
- CONGENITAL MALFORMATIONS
- Basilar invaginationCerebellar dysgenesis
- Dandy walker malformation
- Chiari malformation
Chronic ataxia with slow progression:
The commonest causes of chronic slowly progressive ataxia are brain tumors (cerebellar astrocytoma-commonest) and hereditary ataxias (Friedreich's Ataxia and Ataxia-Telangiectasia are the commonest).
Brain tumors
- They are always suspected in a previously healthy child who develops progressive ataxia with/without headache.
- The commonest brain tumors causing ataxia are the infratentorial tumors seen commonly in children between 2 to 8 years.
- Supratentorial tumors may also cause ataxia when it involves the input fibers from the frontal lobes to the cerebellum.
Cerebellar astrocytoma
- They are the most common posterior fossa tumors in children.
- These slow-growing tumors arise in the cerebellar hemisphere and typically consist of a large cyst with a mural nodule.
- Headache, signs of raised ICP, and ataxia are the commonest features.
- The head may remain tilted to one side - torticollis. (This is the earliest symptom to develop).
- Brain imaging is useful for diagnosis and treatment consists of surgical removal. -Emergency shunting may be required in case of life-threatening hydrocephalus.
- Majority of the tumors are low-grade with good long-term survival rates.
Ependymoma of the fourth ventricle
- It is derived from the cells that line the roof and floor of the 4th ventricle.
- Patients may develop raised ICP over months and may develop truncal ataxia.
- CT or MRI is useful in diagnosis and treatment consists of surgical removal along with radiation therapy.
Medulloblastoma
- It is a high-grade embryonal tumor arising from the cerebellar vermis or fourth ventricle.
- Medulloblastoma is the most common primary malignant brain tumor in children.
- Patients present with signs of hydrocephalus, rapidly evolving raised ICP, and truncal ataxia due to the aggressive growth of the tumor.
- Treatment consists of surgical removal, radiation, and chemotherapy.
Cerebellar Hemangioblastoma
- Hemangioblastoma is a rare, benign, highly vascular tumor that can occur sporadically or as part of von Hippel-Lindau syndrome(VHL), a neurocutaneous disorder with autosomal dominant inheritance.
- Multiple tumors and cystic lesions involving several organs are seen in VHL.
- While a majority of the patients are diagnosed in the third to a fourth decade, Hemangioblastomas of the cerebellum and retina may be seen in children less than 18 years and should prompt a workup for VHL.
- Treatment of cerebellar hemangioblastomas is by surgical removal. Malignant transformation of CNS lesions is rare.
Hereditary Ataxias
- Inherited ataxias are a heterogenous group of disorders characterised by slow, progressive gait ataxia and other features of cerebellar dysfunction.
- Several disorders have spinal cord involvement, neuropathy which contribute to the gait imbalance.
- Additional neurological features are present - seizures, spasticity, retinopathy which may help in identifying the specific disease type.
- Brain imaging frequently shows cerebellar hypoplasia or progressive atrophy.
- Hereditary ataxias have been classified according to mode of inheritance, with disorders continuing to be added as newer genes get identified.
Spinocerebellar Ataxia:
The autosomal dominant ataxias are now collectively called Spinocerebellar ataxia (SCA) and are numbered in the order they were identified. All the SCAs have considerable overlap and therefore genetic testing is required to determine the type of SCA. SCA3 is most common worldwide. SCA2 is quite common in India.
Most SCAs are due to trinucleotide repeat expansion and several show anticipation, which means that cerebellar dysfunction occurs at an earlier age and with increasing severity in successive generations.
They generally present in adulthood with gait ataxia which is progressive, along with dysarthria, dysmetria, and nystagmus.
Friedreich's ataxia(FRDA):
- It is the most common autosomal recessive ataxia.
- Majority of the cases are due to trinucleotide repeat expansion of the FXN gene.
- The symptoms begin in the first decade of life as unsteady gait with rapid progression.
- Gait imbalance is due to spinocerebellar tract as well as posterior column involvement.
- The deep tendon reflexes are absent or depressed. patients have an impaired vibration & position sense and positive Romberg’s test.
- Extensor plantar reflex and spasticity is present due to involvement of the cortical tracts. Patients always develop dysarthria.
- Along with CNS involvement, skeletal deformities such as scoliosis, flexion contractures of the knees, and pes cavus are seen.
- Cardiomyopathy is seen in two-third of individuals with FRDA.
- These patients also have an increased susceptibility to develop diabetes.
- Optic atrophy, hearing loss, lower urinary tract problems are associated features.
- Diagnosis is confirmed by genetic testing. Nerve conduction study shows reduced sensory nerve action potential.
Neuroimaging in advanced disease shows cerebellar and cervical spinal cord atrophy. Findings may be normal at symptom onset.
- The patients are usually confined to the wheelchair by the early twenties.
- Treatment is only supportive.
Ataxia Telangiectasia:
- It is a rare, autosomal recessive disorder due to mutation in the ATM gene which plays a key response in DNA damage repair.
- Ataxia, predominantly truncal, starts early in childhood. Parents note that the child has started to fall soon after learning how to walk independently.
- Oculomotor apraxia is a key feature.
- Speech becomes slurred and there is difficulty with fine motor movements.
- Telangiectasiae may be present at 2 years of age but become apparent at 4-6 years. They appear first on bulbar conjunctiva and then spread in a butterfly distribution on the face, ears, and neck,
- These children have recurrent sinopulmonary infections, especially with pneumococci, and serum immunoglobulinlevels are decreased or absent.
Serum IgM levels maybe elevated. Thymus has embryonic appearance.
- There is an increased risk of malignancy, particularly leukemia and lymphoma.
- There is increased sensitivity to Xrays and certain cancer chemotherapy agents and therefore should be avoided.
- Alpha-fetoprotein (AFP) level above 10 ng/ml is seen in almost all patients.
- Confirmation of the diagnosis is by genetic testing. Treatment is supportive. Prevention of infection, surveillance for malignancy is essential.
Caveats:
1. AFP levels above 10 ng/ml can be seen as a normal finding in unaffected children until the age of 2 years, hence levels should not be interpreted in isolation.
2. Lymphoid tissue hypoplasia is a constant feature. Therefore enlarged, palpable lymph nodes in a child with AT should raise suspicion for lymphoma.
X-linked Ataxias:
Fragile X tremor/ataxia syndrome (FXTAS) - most common type of X-linked ataxia. Onset of symptoms is in adulthood. The condition is distinct from Fragile X syndrome and occurs in premutation carriers of the FMR1 gene.
Spastic Ataxias:
Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS):
- The classic triad of ARSACS includes cerebellar ataxia, lower limb spasticity, and axonal-demyelinating peripheral neuropathy.
- Brain MRI is characteristic - hypointensities in the pons representing involvement of the corticospinal tracts, and cerebellar atrophy, predominantly of the superior vermis.
- Symptoms occur around the age of 3-4 years and are progressive.
- Treatment is supportive.
Ataxia with Mitochondrial disorders: Mitochondrial disorders such as NARP (neuropathy, pathy, ataxia, retinitis pigmentosa) syndrome have ataxia as a clinical feature. Other mitochondrial disorders with a mutation in the nuclear DNA can also have ataxia as one of the neurological signs.
Congenital malformations
Basilar invagination: It is a craniocervical junction abnormality in which the odontoid process projects above the foramen magnum. As a result, there is pressure over the brainstem structures. Compression of the medulla leads to ataxia and lower cranial nerve palsies. Hydrocephalus and syringomyelia can occur due to obstruction of CSF flow. Diagnosis is made on MRI and treatment includes surgical decompression.
Basilar impression is used interchangeably for basilar invagination. However, in the former, there is additional softening of the bone around the foramen magnum and flattening of the base of the skull.
Chiari Malformation
It describes a group of congenital deformities of the lower brainstem and cerebellum. Spinal cord involvement is primary, as in Chiari II (myelomeningocele) or secondary (syringomyelia due to obstruction of CSF glow). Subtypes range from downward descent of cerebellar tonsils (type I) to occipital encephalocele and cerebellar herniation (type III). The posterior fossa is small. Symptoms are due to crowding and subsequent herniation of the brainstem as well as cerebellar compression. Gait ataxia, lower cranial nerve palsies, signs of brainstem herniation, headaches worsening with Valsalva maneuver are seen. Management includes surgical decompression in symptomatic patients.
Dandy-Walker Malformation (DWM)
This term is used to describe a triad of posterior fossa anomalies - inferior vermian hypoplasia, cystic dilation of the fourth ventricle, and elevation of the torcula and tentorium cerebelli. The posterior fossa appears large, as compared to Chiari malformation where it is small. Milder variants also have been described. In spite of cerebellar involvement, clinical presentation rarely includes ataxia or other cerebellar signs. Hydrocephalus, associated neurological symptoms are commonly seen instead. DWM is seen as part of several genetic syndromes, with congenital rubella, fetal alcohol exposure. Management is symptomatic.
Joubert Syndrome
It is a condition with brainstem and cerebellar malformation that gives rise to the ‘molar tooth' sign on MRI. Ataxia, hypotonia, developmental delays are frequently seen. Breathing abnormalities - apnea, tachypnea are noted in the neonatal period. Eye movement abnormalities - oculomotor apraxia, nystagmus are also seen. Diagnosis is by clinical features and neuroimaging. Prominent interpeduncular fossa, thickened and elongated superior cerebellar peduncles, and hypoplasia of the cerebellar vermis cause the brainstem to have the appearance of a molar tooth on axial view on MRI. . Renal and hepatic involvement may occur in some cases, routine surveillance is important. Several genes causing Joubert Syndrome have been identified. Treatment is supportive.
Some of the Treatable Causes of Ataxia:
Most ataxias, whether acquired or hereditary do not have any specific treatment; management is supportive. However, a few are potentially treatable.
- Hartnup disease:
It is an autosomal recessive metabolic error associated with massive aminoaciduria and nicotinamide deficiency. Tryptophan, instead of being converted to nicotinamide is converted to indole derivatives. Patients present with pellagra like itching eruptions on visible parts of the skin, ataxia, nystagmus, double vision, and exaggerated deep tendon reflexes. Mental changes in form depression, confusion, hallucination may also be seen. Treatment is by giving large doses of oral nicotinamide along with a high protein diet.
- Ataxia with Vitamin E deficiency (AVED)
Rare, autosomal recessive disorder presenting between the age of 5 years to adolescence. Neurological features are similar to Friedrich’s ataxia. Low levels of Vitamin E, normal lipid profile, and lipoprotein levels are seen. Neuroimaging findings are not specific for AVED. Cerebellar atrophy and T2 white matter hyperintensities are seen. Neuropathy is present with abnormal somatosensory evoked poentials(SSEP), reflecting posterior column involvement. Diagnosis is confirmed by genetic testing. Treatment is lifetime supplementation of a high dose of Vitamin E (40 mg/kg).
- Cerebrotendinous xanthomatosis (CTX)
Lipid storage disorder with neurological and psychiatric features, cataracts, and diarrhea. Key finding is the presence of xanthomas, typically over the Achilles tendon. Neurological symptoms generally occur in adulthood. Brain MRI shows hyperintensity of the dentate nuclei and cerebellar white matter, cerebral and cerebellar volume loss. Biochemical features include high plasma and tissue cholestanol concentration, normal-to-low plasma cholesterol concentration, decreased chenodeoxycholic acid. Treatment is life-long supplementation with chenodeoxycholic acid.
Common Causes of Ataxia in Different Age Groups
Ataxia in children before 1 year of age:
- Congenital malformations
- Mild arrested hydrocephalus
- Cerebral Palsy
- Marinesco - Sjogren syndrome
Ataxia in children between 1-5 years of age:
- Drug Ingestion
- Acute cerebellar ataxia
- Opsoclonus Myoclonus Ataxia syndrome (OMA/OMS)
- Inborn errors of Metabolism
- Brain tumors
- Ataxia Telangiectasia
- Refsum's disease
Ataxia in Children between 5-10 years
- Drug Ingestion
- Acute Cerebellar Ataxia
- Brain tumors
- Wilson's disease
- Adrenoleukodystrophy
- Hereditary Ataxias
Ataxia in children above 10 years of age:
- Friedreich's Ataxia
- Miller Fisher Syndrome
- Cerebellar hemorrhage
- Multiple Sclerosis
- Olivopontocerebellar degeneration
- Hereditary Ataxias
Presentation
- With Rapid Improvement
- With Prolonged or Intermittent Course
- With Insidious Onset and Slow Progression
Investigations in Acute Cerebellar Ataxia
Workup should be tailored depending on the suspected condition
Investigations include:
Management:
- Management of ataxia is supportive. Few conditions are potentially treatable; specific supplementation or medication may halt progression of disease with recovery in some.
- Therapy - occupational therapy, physiotherapy for gait imbalance, fine movement coordination.
- Speech therapy helps for dysarthria
- Use of walking aids
Summary:
- Pediatric ataxia is seen in several neurological disorders - acquired and hereditary
- More than a 100 metabolic disorders can present with ataxia, in addition to other neurological features.
- For assessment of ataxia - a detailed history including family history, onset of symptoms (acute, subacute, intermittent, chronic) and thorough neurological exam, with special attention to mental status, tendon reflexes, cerebellar signs,pyramidal and extrapyramidal signs, proprioceptive and vestibular exam is essential.
- Look out for the treatable causes of ataxia
- Conditions that should not be missed - OMA/OMS and brain tumors