Loss of Position Sense (Impaired Proprioception)

What proprioception is

Proprioception is the body's sense of its own position and movement. Sensors called proprioceptors in muscles, tendons and joint capsules detect stretch and tension. Their signals travel through large, fast peripheral nerve fibers to the spinal cord, up the dorsal columns (the back of the cord) to the brainstem, cerebellum and finally the sensory cortex.

Balance relies on three inputs: vision, the inner ear (vestibular system) and proprioception. When proprioception fails, people rely on vision. That is why problems appear in the dark, in the shower with eyes closed, or when washing the face.

Symptoms of lost position sense

• unsteadiness, especially in the dark or on uneven ground
• needing to watch your feet while walking
• a wide-based, stamping gait (slapping the feet down to feel the floor), called sensory ataxia
• falls
• clumsy hands, difficulty with buttons, keys or handwriting
• fingers moving involuntarily when the arms are held out with eyes closed (pseudoathetosis)
• often with numbness, tingling or reduced vibration sense

Causes

Peripheral nerve causes

• Peripheral neuropathy: especially from diabetes, alcohol, chemotherapy (cisplatin, oxaliplatin) and high-dose vitamin B6.
• Sensory neuronopathy (ganglionopathy): damage to sensory nerve cell bodies, seen with Sjogren's syndrome, paraneoplastic syndromes and cisplatin. It can cause severe, widespread loss of position sense including the arms.
• Miller Fisher syndrome and Guillain-Barre syndrome.
• Inherited neuropathies and Friedreich's ataxia.

Spinal cord causes

• Vitamin B12 deficiency: causes subacute combined degeneration of the dorsal columns, with tingling, loss of position and vibration sense, and later weakness. Nitrous oxide misuse inactivates B12 and can trigger it rapidly. Copper deficiency (after gastric surgery or excessive zinc) causes the same picture.
• Spinal cord compression: from cervical spondylosis, disc herniation, tumors or abscess.
• Multiple sclerosis: inflammation in the dorsal columns.
• Tabes dorsalis: a late form of neurosyphilis, now rare.
• HIV-associated myelopathy and other infections.

Brain causes

Strokes or tumors affecting the thalamus or parietal cortex can cause one-sided loss of position sense, usually with other signs.

Aging and other factors

Proprioception declines gradually with age, contributing to falls. Joint injuries and arthritis can also impair joint position sense locally, for example after an ankle sprain.

How doctors test position sense

• Joint position test: with your eyes closed, the examiner moves your big toe or finger up or down by a few millimeters and asks which direction it moved.
• Romberg test: you stand with feet together, first with eyes open, then closed. If you are steady with eyes open but sway or fall with eyes closed, the test is positive, pointing to a proprioceptive (sensory) cause rather than a cerebellar one.
• Vibration sense with a tuning fork, which travels in the same pathway.
• Finger-to-nose and heel-to-shin testing, which worsens with eyes closed in sensory ataxia.
• Reflexes and strength: absent ankle reflexes suggest neuropathy; brisk reflexes and stiffness suggest spinal cord disease. B12 deficiency can produce both.

Tests to find the cause

• blood tests: vitamin B12 (with methylmalonic acid and homocysteine), folate, copper, glucose and HbA1c, thyroid function, syphilis serology, HIV, protein electrophoresis
• nerve conduction studies and EMG
• MRI of the cervical and thoracic spine, and of the brain if MS is suspected
• sometimes a lumbar puncture or antibody testing for paraneoplastic disease

Treatment

• Treat the cause: B12 injections for deficiency (start promptly, as damage can become permanent), copper replacement, stopping nitrous oxide, alcohol or toxic drugs, controlling blood sugar, surgery to relieve spinal compression, MS treatment.
• Physical therapy: balance and gait training, strengthening and proprioceptive exercises help the brain use other senses to compensate.
• Occupational therapy: aids for buttons and fine tasks.
• Fall prevention: night lights, grab bars in the bathroom, removing trip hazards, a cane or walker, sturdy shoes.

Frequently asked questions

What does loss of position sense mean?

It means your brain is not receiving accurate information about where your limbs and joints are. You may feel unsteady, especially with your eyes closed or in the dark, and have trouble with fine hand movements. It is caused by damage to sensory nerves or the spinal cord pathways.

What is the Romberg test?

The Romberg test checks balance with your feet together, first with eyes open and then closed. If you stay steady with eyes open but sway or fall with eyes closed, it suggests a loss of position sense rather than a problem in the cerebellum.

Can vitamin B12 deficiency cause loss of proprioception?

Yes. B12 deficiency damages the spinal cord's dorsal columns and peripheral nerves, causing tingling, loss of position and vibration sense, and unsteady walking. It is treatable, but nerve damage can become permanent if replacement is delayed, so testing is important.

Can proprioception be improved?

Yes, often. Treating the cause can allow recovery, and balance training with a physical therapist helps the brain make better use of vision and inner ear signals. Exercises like standing on one leg, tai chi and walking on varied surfaces can improve stability.

Why am I unsteady in the dark?

In the dark, you lose visual input and rely more on position sense from your feet and legs. If that input is reduced, for example from neuropathy or B12 deficiency, you become unsteady. Inner ear problems can also cause this. A doctor can test which system is affected.