Discussion
Most cases of unilateral LMN facial nerve palsy are idiopathic, referred
to as Bell’s palsy. However, cases of bilateral LMN facial nerve palsy
are predominantly attributed to underlying systemic conditions [4].
GBS is an autoimmune-mediated polyradiculoneuropathy characterized by
rapidly evolving ascending weakness, mild sensory loss, and hypo- or
areflexia, progressing to a nadir over up to four weeks. Evaluation of
cerebrospinal fluid demonstrates albuminocytologic dissociation in 90%
of cases. Acute inflammatory demyelinating polyneuropathy (AIDP) is the
most common form of GBS in which the immune attack is directed at
peripheral nerve myelin. Besides this classic presentation, there are
clinical variants based on the types of nerve fibers involved (motor,
sensory, sensory and motor, cranial or autonomic), the predominant mode
of fiber injury (demyelinating versus axonal), and the presence of
alteration in consciousness (5). Acute motor axonal neuropathy (AMAN) is
unique as there is no sensory involvement, and the reflexes are
preserved. Acute Motor and Sensory Axonal Neuropathy (AMSAN), Miller
Fisher Syndrome (MFS), Bickerstaff encephalitis,
pharyngeal-cervical-brachial weakness, pan-dysautonomia, pure sensory
GBS, sixth nerve palsy with paresthesia and facial diplegia with
paresthesia (FDP) are the other rare variants of GBS [6]. Isolated
facial diplegia is a rare variant of GBS, with only a few cases
described so far. Deep tendon reflexes are generally absent but rarely
can be present or even exaggerated (7) As in the case of our patient,
ankle reflexes were absent, and knee and upper limb reflexes were
decreased. Diagnosis of GBS is based on clinical examination, CSF
analysis and neurophysiological studies. CSF shows albuminocytological
dissociation as also seen in our case. NCV and EMG are helpful in
establishing a diagnosis of GBS [8], however may often have
nonspecific EMG findings in patients with facial diplegia. Treatment of
GBS includes supportive care and disease modifying therapy with
intravenous immunoglobulin (IVIG) or plasma exchange (PE) [9].
Commonly, bilateral FN palsy will initially start from one side and
progress to involve the other side subsequently. Our case is rare due to
the synchronous presentation of bilateral facial involvement on the
initial presentation. Approximately 80% of patients diagnosed with GBS
are able to independently walk at six months with complete recovery of
motor strength in 60% of patients at one year [10]. Up to 10% of
patients with GBS may experience relapses with increased weakness. Our
case was unique as the onset of facial palsy was sudden on both sides
and not associated with any distal paresthesia and later progressed to
absent ankle reflexes and decreased knee and upper extremity reflexes.
Absence of deep tendon reflexes, albuminocytological dissociation of
CSF, nerve conduction study findings, and improvement with IVIG favored
a diagnosis of GBS variant, while all other possible differentials were
ruled out through appropriate tests.