Dissociated sensory loss
Encyclopedia
Dissociated sensory loss is a pattern of neurological
damage caused by a lesion
to a single tract in the spinal cord
which involves selective loss of fine touch and proprioception
without loss of pain and temperature
, or vice-versa.
Understanding the reason this is possible requires a brief discussion of the anatomy
involved.
Loss of pain and temperature are due to damage to the lateral spinothalamic tract
s, which cross the central part of the cord close to the level where they enter it and travel up the spinal column on the opposite side to the one they innervate (i.e. they ascend contralaterally). Note that a lesion of the lateral spinothalamic tract at a given level will not result in sensory loss for the dermatome of the same level; this is due to the fibers of the tract of Lissauer which transmit the neuron one or two levels above the affected segment (thus bypassing the segmental lesion on the contralateral side).
Loss of fine touch and proprioception are due to damage to the dorsal column
s, which do not cross the cord until the brainstem, and so travel up the column on the same side to the one they innervate (i.e. they ascend ipsilaterally).
This means that a lesion of the dorsal columns will cause loss of touch and proprioception below the lesion and on the same side as it, while a lesion of the spinothalamic tracts will cause loss of pain and temperature below the lesion and on the opposite side to it.
Dissociated sensory loss always suggests a focal lesion within the spinal cord or brainstem.
The location of cord lesions affects presentation - for instance, a central lesion (such as that of syringomyelia
) will knock out second order neurons of the spinothalamic tract as they cross the centre of the cord, and will cause loss of pain and temperature without loss of fine touch or proprioception.
Other causes of dissociated sensory loss include:
Neurology
Neurology is a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue,...
damage caused by a lesion
Lesion
A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...
to a single tract in the spinal cord
Spinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
which involves selective loss of fine touch and proprioception
Proprioception
Proprioception , from Latin proprius, meaning "one's own" and perception, is the sense of the relative position of neighbouring parts of the body and strength of effort being employed in movement...
without loss of pain and temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
, or vice-versa.
Understanding the reason this is possible requires a brief discussion of the anatomy
Anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...
involved.
Loss of pain and temperature are due to damage to the lateral spinothalamic tract
Spinothalamic tract
The spinothalamic tract is a sensory pathway originating in the spinal cord. It transmits information to the thalamus about pain, temperature, itch and crude touch...
s, which cross the central part of the cord close to the level where they enter it and travel up the spinal column on the opposite side to the one they innervate (i.e. they ascend contralaterally). Note that a lesion of the lateral spinothalamic tract at a given level will not result in sensory loss for the dermatome of the same level; this is due to the fibers of the tract of Lissauer which transmit the neuron one or two levels above the affected segment (thus bypassing the segmental lesion on the contralateral side).
Loss of fine touch and proprioception are due to damage to the dorsal column
Posterior column-medial lemniscus pathway
The posterior column-medial lemniscus pathway is the sensory pathway responsible for transmitting fine touch, vibration and conscious proprioceptive information from the body to the cerebral cortex; as well as tactile pressure, barognosis, graphesthesia, stereognosis, recognition...
s, which do not cross the cord until the brainstem, and so travel up the column on the same side to the one they innervate (i.e. they ascend ipsilaterally).
This means that a lesion of the dorsal columns will cause loss of touch and proprioception below the lesion and on the same side as it, while a lesion of the spinothalamic tracts will cause loss of pain and temperature below the lesion and on the opposite side to it.
Dissociated sensory loss always suggests a focal lesion within the spinal cord or brainstem.
The location of cord lesions affects presentation - for instance, a central lesion (such as that of syringomyelia
Syringomyelia
Syringomyelia is a generic term referring to a disorder in which a cyst or cavity forms within the spinal cord. This cyst, called a syrinx, can expand and elongate over time, destroying the spinal cord. The damage may result in pain, paralysis, weakness, and stiffness in the back, shoulders, and...
) will knock out second order neurons of the spinothalamic tract as they cross the centre of the cord, and will cause loss of pain and temperature without loss of fine touch or proprioception.
Other causes of dissociated sensory loss include:
- Diabetes mellitusDiabetes mellitusDiabetes mellitus, often simply referred to as diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced...
- SyringomyeliaSyringomyeliaSyringomyelia is a generic term referring to a disorder in which a cyst or cavity forms within the spinal cord. This cyst, called a syrinx, can expand and elongate over time, destroying the spinal cord. The damage may result in pain, paralysis, weakness, and stiffness in the back, shoulders, and...
- Brown-Séquard syndromeBrown-Séquard syndromeBrown-Séquard syndrome, also known as Brown-Séquard's hemiplegia and Brown-Séquard's paralysis, is a loss of sensation and motor function that is caused by the lateral hemisection of the spinal cord...
- Lateral medullary syndromeLateral medullary syndromeLateral medullary syndrome is a disease in which the patient has a constellation of neurologic symptoms due to injury to the lateral part of the medulla in the brain, resulting in tissue ischemia and necrosis.-Signs and symptoms:This syndrome is characterized by sensory deficits affecting...
aka Wallenberg's syndrome - Anterior spinal arteryAnterior spinal arteryIn human anatomy, the anterior spinal artery is the blood vessel that supplies the anterior portion of the spinal cord. It arises from branches of the vertebral arteries and is supplied by the anterior segmental medullary arteries, including the artery of Adamkiewicz, and courses along the anterior...
thrombosisThrombosisThrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss... - Tangier diseaseTangier diseaseTangier disease is a rare inherited disorder characterized by a severe reduction in the amount of high density lipoprotein , often referred to as "good cholesterol," in the bloodstream.-Diagnosis:...
- Subacute combined degeneration
- Multiple sclerosisMultiple sclerosisMultiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
- Tabes dorsalisTabes dorsalisTabes dorsalis is a slow degeneration of the sensory neurons that carry afferent information. The degenerating nerves are in the dorsal columns of the spinal cord and carry information that help maintain a person's sense of position , vibration, and discriminative touch.-Cause:Tabes dorsalis is...
- Friedreich's ataxiaFriedreich's ataxiaFriedreich's ataxia is an inherited disease that causes progressive damage to the nervous system, resulting in symptoms ranging from gait disturbance to speech problems; it can also lead to heart disease and diabetes....
(or other spinocerebellar degeneration)