Case presentation:
A 61-year-old right-handed male, non-smoker, with no known past medical
history, presented to the emergency department with five months history
of progressive episodic unprovoked dysarthria of 10-15 seconds that
occurred up to 30-40x day with intact awareness and comprehension. No
specific aggravating factors and episodes do not exhibit diurnal
variability. No history of preceding illness, trauma, and no
constitutional symptoms were present. A review of systems revealed no
extra-neurological manifestations, no mouth, genital ulcers, or blurred
vision. No relevant family history, namely PDA, cerebellar ataxia,
stammering, or stuttering.
Initial vitals were within normal parameters, temperature of 36 °C,
respiratory rate of 19 breaths per minute, blood pressure of 120/62mmHg,
oxygen saturation of 98%, and weight of 75 kg. His neurological
examination was significant only for right dysmetria, dysdiadokokinesia,
and inability to tandem. During the consultation, episodes were
witnessed of 10-20 seconds stereotyped ataxic dysarthria with dysprosody
and none unintelligible, pointing towards paroxysmal ataxia and
dysarthria (PAD). Neuropsychological assessment was unrevealing, with
normal Mini-Mental State Examination (MMSE) 29/30.
Initial workup; MRI head with contrast, showed 5 x 8 x 6 mm homogenously
enhancing midbrain lesion a midline lesion with suspicious thickening
and increased enhancement of left third cranial nerve, that raised the
suspicion of underlying neoplastic vs. inflammatory etiology, such as
lymphoma, glial tumors, or neuro-sarcoidosis or neuro-Bechet’s disease
(Figure 1 A-D). Subsequent, full-body positron emission tomography (PET)
and skeletal survey scan only showed a midline midbrain lesion with
relative hypermetabolism otherwise unrevealing, excluding malignancy or
other inflammatory processes. PET scan. Three months follow-up MRI head
showed regression of the lesion (Figure 2 A-D), indicative of likely
inflammatory process, and less likely glioma and metastasis, considering
the interval minimal regression in size.
Lumbar puncture was performed, showed no pleocytosis, normal
cerebrospinal fluid (CSF) biochemistry, culture for bacteria, and nPCR
assays for a broad panel of viruses were negative. No malignant cells
visible on cytology, and flow cytometry was not done due to paucity of
cells, and no oligoclonal bands were detected. Blood tests were within
normal parameters, including autoimmune workup and angiotensin
converting enzyme level (ACE) 61 U/L (16-85 is normal reference range).
Despite the possible differential of glial tumor or lymphoma, a brain
biopsy was deferred and not advised by the Neurosurgery team due to high
risk. Due to anatomical location and radiological features, a possible
diagnosis of neuro-Bechet’s was considered. The ophthalmology
examination was normal, with no evidence of anterior or posterior
uveitis on slit-lamp examination. Further HLA B-51 (Allele 2) analysis
was requested (usually takes 3-4 weeks).
The patient was started on pulsed steroids with one gram of intravenous
methylprednisolone for five days with a tapered dose (IVMP), which did
not note any significant improvement in the frequency of his paroxysmal
ataxia and dysarthria episodes. He was started on 200mg Carbamazepine
and discharged home with regular follow-ups in the General Neurology
clinic.
On four weeks follow-up, the patient developed fever, deranged liver
function test (LFT), and severe skin maculopapular rash on more than
one-third surface area, suggestive of Anti-convulsant Hypersensitivity
Syndrome (AHS), significant enough to discontinue Carbamazepine and was
switched to Baclofen. His PDA episodes were not adequately under
control; hence a trial of Lacosamide 50mg BID controlled his PDA
episodes.
1
On five weeks follow up, HLA B-51 results reported positive, raising the
diagnosis of PAD in neuro-Behcet’s with atypical radiological and
clinical findings. Per Behcet’s syndrome Japanese Ministry of health and
welfare criteria, our patient has one minor criterion due to a
symptomatic central nervous system (CNS) lesion. A three-month follow-up
MRI head showed slight interval regression in the midline midbrai1n
lesion size to 4 x 7 x 5 mm in maximum AP, with decreased perilesional
edema (Figure 2 A-B).