Definition

Dorsal root syndrome (posterior radicular syndrome) is a collection of symptoms caused by damage to the posterior root. The posterior root is a structure composed of nerve cells that function to transmit sensory sensations from sensory receptors in the human senses to the brain. If there is a disturbance in the posterior root, a person will experience difficulties in feeling pain, knowing body position, and sensing heat or cold partially or completely. This condition can be caused by various factors, including genetic causes, infections, immune disorders, drug intoxication, and others.

Causes

To transmit and process information, our body has two important structures, the anterior root and the posterior root. These two structures are directly connected to the spinal cord and have different functions. The anterior root functions to transmit signals from the brain to target organs, while the posterior root functions to transmit signals from the body's senses to the brain. Sensory stimuli are captured by receptors in the human senses and transmitted through nerves. These nerves converge to form the posterior root. Once transmitted through the posterior root, the information reaches the spinal cord, is classified by type, and sent to the brain through different pathways. The brain processes this information, allowing humans to feel sensations such as pain, cold, heat, and touch. Additionally, the posterior root is responsible for transmitting information related to body position, muscle stretch, and vibration.

The posterior root is more susceptible to damage due to its thinner barrier structure, making it more easily exposed to toxins, inflammatory processes, and infections. In cases of infection or malignancy in the body, immune cells attempt to resolve the condition through inflammation. The effects of inflammation, while alleviating infection, can also damage organs, including the posterior root. Immune cells like T lymphocytes, B lymphocytes, and macrophages can damage the myelin sheath of the posterior root, leading to injury. Other factors such as aging, mechanical compression of the posterior root, autoimmune conditions, and reduced blood supply to the posterior root can also cause damage. When damage occurs, a person will experience symptoms collectively referred to as dorsal root syndrome.

Disorders of the posterior root can be caused by:

• Autoimmune conditions, such as sarcoidosis, Sjögren's syndrome, systemic lupus erythematosus (SLE)
• Degenerative processes (aging)
• Spinal injuries
• Compression of nerves and blood vessels leading to decreased blood supply
• Infections such as syphilis, leprosy, hepatitis C
• Metabolic diseases such as diabetes, hyperlipidemia
• Toxic substances such as alcohol
• Cancer. One antibody implicated in posterior root damage is the anti-Hu antibody found in lung, prostate, ovarian, and breast cancer patients

Risk factor

Factors that increase the risk of someone developing dorsal root syndrome include:

• Old age, as degenerative processes can damage the posterior root
• Spinal injuries
• Autoimmune conditions
• Cancer
• HIV/AIDS
• Cancer therapy (cisplatin)
• Vitamin B6 deficiency
• Alcohol consumption

Symptoms

Symptoms of dorsal root syndrome include:

• Inability or reduced ability to feel sensory stimuli, such as pain, temperature, body position, and vibration
• Difficulty maintaining position (ataxia)
• Reduced body reflexes
• Autonomic signs, such as orthostatic hypotension, digestive disorders, and erectile dysfunction
• Tingling sensations and electric shock-like feelings
• Numbness, especially in diabetes patients

Diagnosis

The doctor will inquire about your complaints and previous medical history that are risk factors for dorsal root syndrome.

Diagnosis of this condition can be made through neurological examinations. Sensory skin tests can be performed to assess the ability to feel touch, vibration, pain, and proprioceptive (body position) sensations. Sensory tests can help estimate the location of the damage. Tests are conducted by comparing the right and left sides of the body. If there is damage on both sides, sensory tests become more difficult to perform. Motor examinations generally do not reveal weakness in limbs, but body reflexes may be reduced.

Several supporting examination modalities can be used to establish a diagnosis, including:

• Electromyography (EMG). In EMG examinations, neuropathy conditions can show decreased sensory nerve action potentials. However, this examination can also yield normal results.
• Skin biopsy. This examination is the gold standard in diagnosing dorsal root syndrome. Its sensitivity and specificity for diagnosing this condition are 90% and 97%, respectively. The sample is taken from the foot, about 10 cm from the ankle. In dorsal root syndrome, there is a reduced number of nerve cells, immune cell clusters (Nageotte nodules), and ganglion cell degeneration.
• Imaging examinations. Imaging examinations such as MRI can be performed to evaluate the anatomy of the spinal cord, especially in individuals with long-standing complaints.

Management

Currently, there are no specific guidelines for treating this condition. Some studies show that medications such as anticonvulsants, serotonin-norepinephrine reuptake inhibitor (SNRI) antidepressants, tricyclic antidepressants, opioids, and botox injections can help reduce symptoms compared to placebo. However, further research is needed.

Treatment of dorsal root syndrome mainly focuses on symptom management. If pain is present, your doctor will prescribe pain relievers such as paracetamol and non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen. Antidepressants and anticonvulsants can help patients tolerate pain.

Other treatments that can be used include acupuncture, relaxation techniques, and heat or cold therapy. Physical therapy can help manage ataxia.

Complications

Complications from poorly managed dorsal root syndrome include:

• Injuries. Reduced sensation and the body's ability to detect harmful stimuli, such as heat or sharp objects, can lead to injuries.
• Infection. Individuals with dorsal root syndrome may not realize they have an injury, allowing it to become infected. This infection can lead to gangrene (tissue necrosis/death) and potentially life-threatening sepsis.
• Falls. Patients with dorsal root syndrome can experience difficulties processing their body position (proprioceptive function), making them more prone to falls, especially in the elderly.

Outcomes for dorsal root syndrome vary depending on the degree of nerve damage and the underlying cause. For instance, patients with uncontrolled blood sugar levels can see improvement if their blood sugar is managed. Generally, pain and temperature sensations are the first to return.

Prevention

• Manage your medical conditions. Keeping blood sugar levels within normal limits and taking medications for autoimmune conditions can reduce the risk of developing dorsal root syndrome.
• Use protective gear. To prevent complications from dorsal root syndrome, avoid injuries by using protective gear. Check your hands and feet daily for any injuries.
• Improve your lifestyle. Consuming a balanced diet and engaging in physical activity can maintain nerve health and prevent conditions that can lead to dorsal root syndrome, such as diabetes and vitamin B6 deficiency.
• Reduce alcohol consumption. Alcohol is a risk factor for dorsal root syndrome. Reducing or stopping alcohol consumption can prevent this condition.

When to see a doctor?

If you experience symptoms of sensory loss and have other medical conditions that can lead to dorsal root syndrome or have a family history of the syndrome, seek medical attention at a nearby healthcare facility.