Landau-Kleffner Syndrome, Attention-Deficit/Hyperactivity Disorder (ADHD), and Viral/Autoimmune Encephalitis: Challenges in the Diagnosis and Management of a Six-Year-Old Boy.

In this case, we discuss the difficulties and challenges faced when diagnosing and treating a six-year-old boy presenting with abnormal behaviors and difficulty in concentration and inattentiveness, followed by regression of expressive language. These symptoms were then followed by hyperactivity, bouts of anger, and difficulty sleeping. The patient was seen by a psychiatrist, and he was diagnosed with attention-deficit/hyperactivity disorder (ADHD) initially and treated with little to no improvement. He was then recommended to see a neurologist by his psychiatrist and underwent a series of investigations, which included the following: brain MRI with contrast, magnetic resonance (MR) spectroscopy, cerebrospinal fluid (CSF) routine, CSF N-methyl-D-aspartate (NMDA) receptor antibody and glutamate decarboxylase (GAD) antibody analysis, and a CSF meningitis multiplex polymerase chain reaction, thyroid function, ammonia, lactate, creatine kinase, liver function, and metabolic screening of urine organic acids (UOAs), all of which revealed no abnormalities. Vitamin D was low at 38 ng/ml (>50). An electroencephalogram (EEG) done under standard conditions and provocative stimulation was abnormal with bilateral central and frontal discharge and more activity on the right side, revealing a background activity of moderately organized alpha waves (8-13 Hz) and bursts of sharp and slow wave activities that were accentuated by photic stimulation. Polysomnography showed poor sleep efficiency of 84.7%, and rapid eye movement (REM) stage was not reached due to interrupted sleep. He was then diagnosed with epileptic encephalopathy and Landau-Kleffner syndrome (LKS). The patient was prescribed sodium valproate, intravenous immunoglobulin (IVIG), and pulse steroids, with no major improvement, risperidone was added but was poorly tolerated, and the dose tapered off and eventually discontinued. Methylphenidate was the prescribed starting at 5 mg, and the dose was gradually increased to 20 mg/day given separately as 10 mg twice a day. A week later, melatonin 2 mg was added. Three months, later the EEG was repeated and was normal, and sodium valproate was tapered off and eventually discontinued. Later on that year, he was diagnosed with COVID-19 and developed acute myositis as a complication, methylphenidate was stopped, and only sertraline and melatonin were continued. MRI was repeated only this time, showing evidence of viral/autoimmune encephalitis (AIE) sequela, and IV corticosteroids were given alongside IVIG. He was discharged on prednisolone, and a month later, major improvements were seen in all aspects.