Sensory Ataxia

Original Editor - Shreya Vaghela Top Contributors - Olajumoke Ogunleye, Kim Jackson, Lucinda hampton and Shreya Vaghela

Introduction

ATAXIA is a general term used to describe the combined influence of cerebellar and sensory dysfunction on gait, posture, and patterns of movement.

Ataxia due to Sensory Impairment.

Sensory Ataxia (SA) is a form of Ataxia caused by the impairment of the somatosensory nerve, leading to the interruption of sensory feedback signals. It is characterized by postural instability and incoordination that diminish due to visual input contributing to functional deficits and gait impairments. SA leads to a lack of muscle movement coordination caused by a loss of the sense of where different parts of the body are located to each other and the ground.

Causes are:

• Peripheral nerve: Peripheral neuropathy (especially Diabetic, Alcoholic and Nutritional), Peripheral neuritis.
• Posterior root: Tabes dorsalis.
• Posterior column: Subacute combined degeneration of the cord, Demyelination changes of the posterior column.

Mechanism/ Pathophysiology

SA is caused by interference in the sensory transmission to the cerebellum caused by a lesion. It is the sensory damage to the posterior column due to loss of connection between the cerebellum and spinal cord and lack of proprioceptive information.

Clinical Presentation

The presence of the following are associated with SA:

• Kinetic Tremors which appear only on the closure of the eyes.

• Psuedoathetosis is the random finger movements seen on outstretched hands with eyes closed and may occur in sensory neuronopathy affecting the upper limbs.

• Deep Sensory Loss such as - proprioception, kinesthetic awareness, vibration sense.

• Positive Rhomberg's Test - when the patient stands with his feet close together & his eyes closed, his body sways & he may fall if not supported. The visual system can provide compensation information when the eyes are open, so the patient can remain upright and stable; Visual compensation would disappear when the eyes are closed, and patients will not be able to maintain upright stability.

• Sensory Gait/High Stepping Gait/Feet Slapping Gait - when who does not have SA walks, the sensory nerve would be stimulated when the sole touches the ground, then the relevant information is transmitted to indicate the position of the feet. Since the patients with sensory ataxia lose the input of the stimulus, to know the time and place the feet land, the patient would put his feet on the ground heavily. The key to this gait is that when patients can’t see their feet (e.g., in the dark), stepping will increase obviously. This gait is sometimes referred to as a stepping gait, because patients may lift their legs to a very high position.
  • Heavy strike of the ground on walking due to lost deep sensation.
  • High-stepping gait due to associated motor weakness
  • Feet-slapping gait - to assist with sound-induced sensory feedback.

Diagnosis

Sensory ataxia can be diagnosed clinically using a combination of strategies that may include medical history, family history, and a complete neurological evaluation. Laboratory tests may also be carried out, including:

• Imaging studies such as CT scans and MRI. This is used to know the integrity of the cerebellum and other brain structures.
• Lumbar puncture
• Genetic testings

Treatment

The main focus of sensory ataxia treatment is to stop the progress of the nerve damage, alleviate symptoms, increase independence and minimize the risk of falls. If a cause is found, then treatment, where possible, will address the underlying cause. For example, vitamin B12 deficiency is treated with vitamin B12 supplementation (typically starting with injections then switching to oral); diabetic neuropathy is managed by maintaining tight sugar control.

Physiotherapy Management

There is little literature regarding the efficacy of Physiotherapy (PT) in this population; however, persons with sensory ataxia experience significant activity limitations that require PT interventions.

• Physical therapy to help your coordination and enhance your mobility
• Occupational therapy to help you with daily living tasks, such as feeding yourself
• Speech therapy to improve speech and aid swallowing