Discussion:
GBS manifests itself in a variety of ways, ranging from typical
peripheral 4 limb weakness with areflexia to numerous variants that
complicate diagnosis and management. Typical GBS usually presents with
ascending limb weakness with hyporeflexia/areflexia with minor sensory
symptoms and usually involves the 4 upper limbs [4]. Besides the
typical presentation of GBS, clinical variants are based on the types of
nerve fibers involved (motor, sensory, sensory, and motor, cranial, or
autonomic) and the mode of fiber injury (demyelinating vs axonal) [5,
6]. The most common mode of nerve fiber injury is demyelinating, while
axonal motor and axonal sensory variants have been described [6] and
are associated with rapid progression and poor prognosis [7]. Axonal
variants are usually preceded by campylobacter jejune infection [8].
GBS typically has ascending weakness, but descending variants have been
described, including the Miller-Fischer variant, which consists of
ophthalmoplegia, ataxia, and areflexia [9]. Another cranial variant
is the Bickerstaff brainstem encephalitis, which is characterized by
alteration in consciousness, hyperreflexia, ataxia, and ophthalmoplegia
[10].
A less common paraparetic motor variant affects the legs selectively
with areflexia, mimicking an acute spinal cord lesion, and is associated
with back pain [11]. In most cases, the paraparetic variant is
usually milder compared to the classical GBS, and in 50% of the cases,
there are abnormalities in upper limb nerves observed in NCS [12].
While the sensory symptoms in GBS are typically mild, pure sensory
variants have been described and are usually characterized clinically by
exclusive sensory symptoms and signs that reach their nadir in a maximum
of 6 weeks without related systemic disorders and other diseases or
conditions [13].
Our case is a 62-year-old lady who presented with progressive ascending
lower limb weakness with areflexia in addition to the sensory level of
T6. MRI excluded spinal cord compression and demyelination. CSF studies
showed albumin-cytological dissociation. NCS showed absent F-waves of
both the perineal and tibial nerves. She was given intravenous
immunoglobulin followed by five days of IV methylprednisolone, and her
symptoms improved over four weeks. Our most likely diagnosis was GBS
based on the presentation of acute flaccid paralysis, areflexia,
preceding diarrheal illness, CSF studies, and lack of evidence of
demyelination and cord compression on MRI, in addition to the duration
and course of her illness. We think that our case is like the case
reported by Khoo et al. and may represent a new variant of GBS [14].
It is important to note that typical NCS findings are not always present
in GBS as it is affected by timing and multiple studies at different
times are needed [15].
Another argument is the possibility of transverse myelitis provided that
our patient has sensory level and with the onset of symptoms typical of
transverse myelitis, but the diagnostic criteria [16] don’t apply in
our case as there is an absence of demyelination in repeated MRI and no
CSF leukocytosis.