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Urinary retention or ileus may also occur. Motor symptoms
usually are present early in disease; cranial nerves are
affected first with blurred vision, diplopia, ptosis, and
photophobia. Bulbar nerve dysfunction causes dyearthria,
dysphonia, and dysphagia. This is followed by a symmetrical,
descending, progressive weakness of the extremities along with
weakness of the respiratory muscles. Development of
respiratory failure may be abrupt.

On physical examination, the patient is alert, orientated,
and afebrile. Postural hypotension may be present. Ocular ~
findings may include ptosis, extraccular muscle paralysis, and
fixed and dilated pupils. Mucous membranes of the mouth may be
dry and crusted. Neurological examination shows flaccid muscle
weakness of the palate, tongue, larynx, respiratory muscles,
and extremities. Deep tendon reflexes vary from intact to
absent. No pathologic reflexes are present, and the sensory
examination generally is normal (although reports suggest that
obtundation or sensory involvement may sometimes occur).

DIAGNOSIS

Routine Laboratory Findings. Routine laboratory findings
are of no value in diagnosis. The cerebrospinal fluid is
normal.

Differential Diagnosis. The occurrence of an epidemic
with large numbers of afebrile patients with progressive
ocular, pharyngeal, respiratory, and muscular weakness and
paralysis hints strongly at the diagnosis. Single cases may
be confused with various neuromuscular disorders such at
atypical Guillian-Barre syndrome, myasthenia gravis, or tick
paralysis. The edrophonium (tensilon) test may be
transiently positive in botulism. Other considerations
include enteroviral infections; but in these patients, fever
is present, paralysis is often asymmetrical, and the
cerebrospinal fluid is abnormal. In the present setting, it
will be necessary to distinguish nerve-agent and atropine
poisoning from botulinum intoxication. Briefly,
organophosphate nerve agent poisoning results in biotic
pupils and copious secretions. In atropine poisoning, the
pupils are dilated and mucous membranes are dry, but central
nervous system excitation with hallucinations and delirium
is present. See Section IV for a more comprehensive
differential.

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