Cephalic tetanus This form of tetanus follows wounds of the face and head. The incubation period is short, 1 or 2 days as a rule. The affected muscles (most often facial) are weak or paralyzed. Nevertheless, during accessions of tetanic spasm, the palsied muscles are seen to contract. Apparently, the disturbance in the facial motoneurons is sufficient to prevent voluntary movement but insufficient to prevent the strong reflex impulses that elicit facial spasm. The spasms may involve the tongue and throat, with persistent dysarthria, dysphonia, and dysphagia. Ophthalmoparesis is known to occur but is difficult to verify because of severe blepharospasm. In a strict sense, these cephalic forms of tetanus are examples of local tetanus that frequently becomes generalized. Many cases prove fatal.
This is made from the clinical features and a history of preceding injury. The latter is sometimes disclosed only after careful questioning, the injury having been trivial, forgotten and entirely healed. The organisms may or may not be recovered from the wound by the time the patient receives medical attention; other laboratory tests, apart from the EMG, are of little value. Serum CK may be moderately elevated if the rigidity is generalized. The EMG recorded from muscles in spasm shows continuous discharges of normal motor units like those recorded from a forceful voluntary muscle contraction. Most characteristic of tetanus, as mentioned earlier, is a loss of the physiologic silent period that occurs 50 to 100 ms after reflex contraction. This pause, normally produced by the recurrent inhibition of Renshaw cells, is blocked by tetanus toxin. In generalized tetanus the loss of the silent period can almost always be demonstrated in the masseter, and it is found in a muscle affected by local tetanus. Interestingly, the silent period is preserved in the stiff man syndrome (see Chap. 45).
Tetany caused by hypocalcemia, the spasms of strychnine poisoning or black widow spider bite, trismus as a result of painful conditions in and around the jaw, the dysphagia of rabies, hysterical spasms, rigidity and dystonic spasms caused by neuroleptic drugs, and the spasms of the stiff man syndrome all resemble the spasms of tetanus but should not be difficult to distinguish when all aspects of these disorders are considered. Nonetheless, the diagnosis is difficult to bring to mind in a nonendemic area.
The death rate from tetanus is approximately 50 percent overall; it is highest in newborns, heroin addicts, and patients with the cephalic form of the disease. The patient usually recovers if there are no severe generalized muscle spasms during the course of the illness or if the spasms remain localized.
This is directed along several lines. At the outset, a single dose of antitoxin (3,000 to 6,000 U of tetanus human immune globulin) should be given along with a 10-day course of penicillin (1.2 million U of procaine penicillin daily), metronidazole (500 mg q6h intravenously or 400 mg rectally), or tetracycline (2 g daily). These drugs are effective against the vegetative forms of C. tetani. Immediate surgical treatment of the wound (excision or debridement) is imperative, and the tissue around the wound should be infiltrated with antitoxin.