Sensory ganglionopathy

 

 

Sensory neuronopathy, also known as sensory ganglionopathy.

 

 

A rare subgroup of peripheral nervous system diseases.

 

 

Characteristics: primary and selective destruction of the dorsal root ganglia neuron in the spinal cord and the trigeminal ganglia neuron in the skull.

 

Patients often report a lack of coordination of muscle movements. 

 

Most cases of sensory ganglionopathy syndrome evolve over a period of days or weeks and is more rapid than typical peripheral neuropathy, and tends to become severe, affecting tactile sensibility to degree that can lead to swallowing reflex impairment because of loss of pharyngeal sensation.

 

The most common cause of sensory neuronopathy is thought to be immune-mediated damage to the dorsal root ganglion neurons. 

 

The sensory ganglia abnormalities are associated with Sjogren’s syndrome, with checkpoints inhibitors. 

 

Sensory ganglionopathy is associated with underlying systemic disease, usually inflammatory or neoplastic, which is often manifested after the development of neurologic symptoms.

In approximately 50% of cases the disorder remains idiopathic.

 

Idiopathic sensory ganglionopathy is also likely be mediated by cytotoxic T cells.

Sensory ganglionopathies are confined to sensory neurons and do not cause weakness. 

 

The sensory ganglia contain cell bodies of the sensory nerves and lie alongside both sides of the spinal cord, appended to the dorsal root of each spinal nerve. 

 

The sensory ganglia contain the cell bodies of sensory nerves and lie alongside both sides of the spinal cord. 

 

The sensory ganglia are appended  to the dorsal root of each spinal nerve.

 

The sensory ganglia  proximal projections are in the sensory nerve roots that into the spinal cord, and the peripheral projections of the sensory fibers of peripheral nerves.

 

Sensory loss occurs when the sensory ganglia are diseased,

 

The sensory ganglia  are associated with general medical disorders and paraneoplastic disorders, in particular. 

 

The typical findings of proximal sensory symptoms and sensory loss with ataxia, and preserved strength in combination is  diagnostic of sensory ganglionopathy syndrome.

 

The most common polyneuropathies result from axonal damage with diabetes and lead to degeneration in the distal parts of the longest nerves and symptoms that begin in the toes, ascend to  the legs, and only later appear in the fingers and proximal parts of the body.

 

Sensory ganglionopathies are not dependent on the length of the axons, and sensory features can start in any of or all territories innervated by sensory neurons, particularly the face, scalp, oral mucosa, trunk, and proximal limbs.

 

Sensory ganglia may be susceptible to autoimmune attacks because of their fenestrated endothelial cells  that form a permeable blood-nerve barrier.

 

Paraneoplastic sensory ganglia abnormalities can be caused by  cytotoxic T cell stimulated by antigens in the tumor that cross react with epitopes on sensory neurons.

 

The proximal projections are sensory nerve roots into the spinal cord, and the peripheral projections of the sensory fibers of peripheral nerves.

 

Associated with sensory loss that occurs when the sensory ganglion is diseased and has close association with general medical disorders and paraneoplastic disorders.

 

The most common cancers associated with sensory ganglianopathy is small cell lung cancer, but the syndrome has been associated with breast, ovary, prostate, colon, gastric cancers, lymphoma, neuroendocrine tumors and others.

 

Sensory symptoms can be acute or insidious in onset and may precede the diagnosis of malignancy by weeks or months. 

 

Other paraneoplastic syndromes may develop such as myelitis, motor neuropathy, Lambert-Eaton myasthenic syndrome, encephalitis, or cerebellar deterioration.

 

Most patients with paraneoplastic sensory gangliionopathy have anti-neuronal antibodies against a 35-40-KD protein of complex for proteins, the Hu antigen, anti-collapsin response mediator protein 5 antibody, or amphophysin found in serum or CSF.

 

Most sensory ganglionopathies affect large nerve fibers and are associated with loss of touch, vibration perception, proprioception, pseudoathetoid  posturing,  a positive Romberg sign, and loss of tendon reflexes.

 

Less frequently, ganglionopathirs can affect small sensory fiber neurons with burning, tingling, and stabbing pains, revealing impaired pinprick and temperature perception but preservation of large fiber sensory functions and reflexes. 

 

 

Less frequently ganglionopathies affect neurons of small sensory  fibers with burning, tingling, and stabbing pains with physical examination revealing impaired pin prick and temperature perception but preservation of large fiber sensory functions and reflexes.

 

The affect of sensory ganglia diseases often also damages the autonomic ganglia, so patients with sensory ganglionopathies may have dysautonomia with orthostatic hypotension, cardiac rhythm, gastric dysmobility, and sweating disturbances.

 

Ganglia may be susceptible to autoimmune attack because of fenestrated endothelial cells that form permeable blood-nerve barrier. 

 

The proximal projections of sensory ganglion cells form the posterior spinal roots containing spinocerebellar fibers and may cause ataxia that simulates cerebellar disease but without dysarthria and nystagmus.

 

 

Paraneoplastic sensory ganglion may be caused by cytotoxic T cells stimulated by antigens in the tumor that cross react with epitopes on sensory ganglia neurons. 

 

It is associated with Sjögren syndrome with checkpoint inhibitors and idiopathic sensory  ganglionopathy are also mediated by cytotoxic T cells.

 

There are rare hereditary sensory ganglionopathies and autonomic neuropathies.

 

Sensory ganglionopathies are confined to sensory neurons and do not cause weakness. 

 

Common polyneuropathies results from axonal damage which leads to degeneration in the distal portion of the longest nerves and symptoms that begin in the toes, ascend the legs, and only later appear in the fingers in proximal parts of the body.

 

Sensory ganglionopathies are not dependent on the length of axons, and sensory features can start in all the areas elevated by sensory neurons, particularly the face, scalp, oral mucosa, trunk, and proximal limbs. 

 

Most sensory ganglionopathies affect the neurons of large nerve fibers and associated with loss of touch, vibration, proprioception, pseudo-athetoid posturing that represents a search for a position in space, Romberg’s sign, and loss of tendon reflexes.

 

It affects both the central and peripheral neurons and their projections, rather than specific sections seen  in  other polyneuropathies. 

 

Causes include: genetic susceptibility, adverse drug reactions and infections.

 

Neuron damage has been linked to abnormal blood supply via the capillaries, leading to the entry of inflammatory cells, proteins and other toxins into the neurons. 

 

CD8 T lymphocytes and some antibodies may be involved in the pathology of the condition.

 

Autopsies show inflammation and loss of ganglion cells in the dorsal root ganglia and Wallerian degeneration of the posterior columns in the spinal cord.

 

Symptoms of sensory neuronopathy are multifocal: often linked to ataxia, lack of voluntary muscle movement coordination and abnormal gait. 

 

Other symptoms may include:

 

Areflexia

 

Pseudoathetotic hand movements

 

Allodynia

 

Tonic pupils

 

Orthostatic hypotension

 

Gastrointestinal effects

 

Erectile dysfunction

 

Memory deficits

 

Behavioral changes

 

Sensory ganglionopathies may impact of all senses modalities including: pain, temperature, position and vibration.

 

Diagnosis: unique symptoms aid in the diagnosis of the condition, suggest a sensory neuronopathy.

 

Nerve conduction studies are the most useful tool to confirm the diagnosis.

 

 

Asymmetric responses are typically seen with sensory neuronopathy.

 

 

Magnetic resonance imaging (MRI) can help identify patients with subtle damage to the dorsal root ganglion neurons.

 

 

Patients suffering from sensory neuronopathy are more likely to be affected by other autoimmune diseases.