Sensory deficits

This chapter will consider methods and devices used to present visual, auditory, and tactual (touch) information to persons with sensory deficits. Sensory atigmentation systems such as eyeglasses and hearing aids enhance the existing capabilities of a functional human sensory system. Sensory substitution is the use of one human sense to receive information normally received by another sense. Braille and speech synthesizers are examples of systems that substitute touch and hearing, respectively, for information that is normally visual (printed or displayed text). 

Association of Pain, neuropathic pain is defined as pain initiated or caused by a primary lesion, dysfunction in the nervous system". Neuropathy can be divided broadly into peripheral and central neuropathic pain, depending on whether the primary lesion or dysfunction is situated in the peripheral or central nervous system. In the periphery, neuropathic pain can result from disease or inflammatory states that affect peripheral nerves (e.g. diabetes mellitus, herpes zoster, HIV) or alternatively due to neuroma formation (amputation, nerve transection), nerve compression (e.g. tumours, entrapment) or other injuries (e.g. nerve crush, trauma). Central pain syndromes, on the other hand, result from alterations in different regions of the brain or the spinal cord. Examples include tumour or trauma affecting particular CNS structures (e.g. brainstem and thalamus) or spinal cord injury. Both the symptoms and origins of neuropathic pain are extremely diverse. Due to this variability, neuropathic pain syndromes are often difficult to treat. Some of the clinical symptoms associated with this condition include spontaneous pain, tactile allodynia (touch-evoked pain), hyperalgesia (enhanced responses to a painful stimulus) and sensory deficits. 

Neurologic focality Symptomatic sensory or motor deficits that point to specific lesions or dysfunction in the brain. 

Helgren, M. E., Cliffer, K. D., Torrento, K. et al. Neurotrophin-3 administration attenuates deficits of pyridoxine-induced large-fiber sensory neuropathy. J. Neurosci. 17 372-382,1997. 

Botulism. Clinical features include symmetric cranial neuropathies (i.e., drooping eyelids, weakened jaw clench, and difficulty swallowing or speaking), blurred vision or diplopia, symmetric descending weakness in a proximal to distal pattern, and respiratory dysfunction from respiratory muscle paralysis or upper airway obstruction without sensory deficits. Inhalational botulism would have a similar clinical presentation as food-borne botulism however, the gastrointestinal symptoms that accompany foodborne botulism may be absent. 

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