Cranial nerves functions

Impairment of eighth cranial nerve function is the most important adverse effect of streptomycin. Vestibular function is most frequently affected, but hearing may also be impaired. Audiometric testing should be performed in patients who must receive streptomycin for more than 2 months. Streptomycin occasionally causes nephrotoxicity. 

Nervous system disorders are diagnosed by examining the patient s mental status, cranial nerve function, motor system reflexes, and sensory systems. An electroencephalogram (EEG) tests higher brain and nervous system functions. 

Monitoring renal and eighth cranial nerve function at onset of therapy is essential for patients with known or suspected renal impairment and also in those whose renal function is initially normal but who develop signs of renal dysfunction. 

Retrobulbar neuritis is the major adverse effect noted in patients treated with ethambutol, Patients usually complain of a change in visual acuity and/or inability to see the color green. Vision testing should be performed on all patients who must receive ethambutol for more than 2 months. Impairment of eighth cranial nerve function is the most important adverse effect of streptomycin, Vestibular function is most frequently affected, but hearing may also be impaired. Audiometric testing should be performed in patients who must receive streptomycin for more than 2 months. Streptomycin occasionally causes nephrotoxicity. 

TABLE 52—2. Cranial Nerve Function and Examples of Testing... 

Thiamine is used to diminish Wernicke-Korsakoff encephalopathy, which is characterized by confusion, memory loss, and loss of cranial nerve function resulting from chronic alcohol abuse. 

Tetanus occurs when Cl. tetani, ubiquitous in the soil and faeces, contaminates wounds, especially deep puncture-type lesions. These might be minor traumas such as a splinter, or major ones such as battle injury. At these sites, tissue necrosis and possibly microbial growth reduce the oxygen tension to allow this anaerobe to multiply. Its growth is accompanied by the production of a highly potent toxin which passes up peripheral nerves and diSuses locally within the central nervous system. It acts like strychnine by affecting normal function at the synapses. Since the motor nerves of the brain stem are the shortest, the cranial nerves are the first affected, with twitches of the eyes and spasms of the jaw (lockjaw). 

The so-called inferior group (B1-B4) projects mainly to brainstem nuclei, the head nuclei of some cranial nerves and the spinal cord. This means that these neurons are well placed for serving a key role in regulation of motor activity, autonomic function and nociception. In addition, there are numerous interconnections between the different... 

The medulla (myelencephalon) is the most caudal part of the brain stem, and is continuous with the spinal cord. It contains several cranial nerve nuclei and part of the reticular formation, which regulates cardiovascular function, respiration, and skeletomotor tone (figure 2.8). The reticular formation consists of several nuclei that form the core of the entire... 

Paresthesias, weakness and paralysis of lower extremity, hypotension, high or total spinal block, urinary retention or incontinence, fecal incontinence, headache, back pain, septic meningitis, meningismus, arachnoiditis, shivering cranial nerve palsies due to traction on nerves from loss of CSF, and loss of perineal sensation and sexual function Rare... 

When a molecule binds with its receptor site the olfactory cells become stimulated and send an impulse along the olfactory nerve. The olfactory nerve is the first cranial nerve. Cranial nerves that carry impulses into the brain are called sensory, while those that carry impulses away are called motor. Sensory information from the olfactory receptors of the nose is carried as a sensory impulse in the olfactory nerve to an area of the brain called the olfactory bulb. It is the olfactory regions of the brain that interpret this sensory information and distinguish different smells. Structures associated with the sense of smell are located in an area of the fore-brain (at the front) called the rhinencephalon. The rhinencephalon is not fully understood and its function is not restricted to olfaction or smelling. The olfactory tract then connects with another area called the neocortex that allows us to be aware of and to recognise odours or smells... 

The PNS is defined as that part of the nervous system external to the brain and spinal cord (Figure 30.1). As such, the PNS includes the cranial nerves, dorsal and ventral spinal roots, spinal nerves and their branches, and ganglia. The primary function of the PNS is to convey sensory and motor information, including informa-... 

The midbrain, pons, cerebellum, and medulla constitute the brainstem (Figure 3.2). The brainstem has three general functions. The first is to receive sensory information from cranial structures and to control muscles of the head. This function of the brainstem is similar to that of the spinal cord. The cranial nerves are constituents of the PNS that provide the sensory and motor innervation of the head and therefore are analogous... 

Encephalopathy, peripheral neuropathy, cerebellar syndromes, autonomic neuropathy, and cranial nerve toxicity represent the range of neurological complications associated with cancer chemotherapy. Dose, route of administration, age of the patient, hepatic and renal function, prior and/or concomitant use of other neurotoxic drugs, and the concurrent use of cranial or CNS radiotherapy can each influence the incidence rate and severity of neurologic symptoms associated with selected chemotherapy drugs. 

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