Craniofacial Muscles

16 Spastic Facial Muscle Disorders
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Another agent that has been investigated for chemodenervation is ricin-mAb35
(Hott et al. 1998 ; Christiansen et al. 2003 ) . Ricin, a potent ribosomal toxin, is conjugated
to a monoclonal antibody to the alpha subunit of the nicotinic acetylcholine
receptor. The agent has been extensively studied in extraocular muscles, with excellent
results. The toxin paralyzes the extraocular muscles for at least 6 months with
no histologic evidence of long-term muscle damage.
16.8.4.3 Selective Facial Nerve Ablation (Neurectomy or Reynolds
Procedure, Differential Section of the Seventh Nerve [CNVII])
Selective facial nerve (CNVII) ablation may be considered in cases refractory to
BoNT and myectomy (Fante and Frueh 2001a ). Among the branches of the facial
nerve, temporal, and zygomatic branches are selectively ablated. This also can be
done by percutaneous thermolysis of the nerve. Recurrence rate is high, and 50% of
patients treated with this technique require more than one operation to control their
spasms. Even in these patients, 50% of the patients have a recurrence of spasms 2
or more years after surgery (Fante and Frueh 2001b ). Its use has declined with the
introduction of BoNT injection as well as the high incidence of complications.
Hemifacial paralysis frequently results from facial nerve dissection. Consequently,
the patients may permanently suffer from dif fi culty in controlling facial expression
and in eating and speaking. Other complications include transient parotid fi stula and
recurrent spasm (Frueh et al. 1992 ; Gillum and Anderson 1981 ; McCord 1984 ) .
16.8.4.4 Superior Cervical Ganglion Block
In some patients in whom BoNT treatment fails, the reason for failure may be the
persistence of severe photophobia (photooculodynia) despite weakening of the
orbicularis muscle. It suggests that the sympathetic nervous system may play a role
in maintaining the afferent loop of the disease.
Photooculodynia can be identi fi ed using a simple clinical test. If patients complain
of signi fi cant spasm and pain with a 25-W light bulb at a distance of 3 ft, a
diagnosis of photooculodynia can be made. These patients are not likely to respond
to myectomy and are referred to a pain clinic for a superior cervical ganglion block
to chemodenervate the orbital sympathetic nerves. It was reported that two-thirds of
patients with photooculodynia had a symptomatic improvement with this treatment
(McCann et al. 1999 ; Fine and Digre 1995 ) .
In summary, although the pathophysiology of blepharospasm is unclear, and there
is no known cure for it, several effective modes of treatment, including botulinum
toxin injection, oral medication, and surgery are currently available. Cumulative success
rates for the treatment of BEB are approximately 85% with BoNT/A injections, 97%
for BoNT/A in conjunction with protractor myectomy, and 98% for a combination of
BoNT/A, myectomy and selective facial nerve ablation (Mauriello et al. 1996 ; Fante
and Frueh 2001 a). Ultimately, most patients (70%) continue to receive BoNT
injections, while 7–11% of the patients spontaneously improve.