Background and Importance STIFF syndrome is a rare disease with genetic mutation Cr 5 GLRA1. It is characterised by a neurological disorder with stiffness and muscle spasms, which affects the quality of life of these patients.

Aim and Objectives Describe the diagnostic and therapeutic management of a neonatal patient with Stiff syndrome.

Material and Methods Literature review of cases described with similar clinical features by the pharmacy and neonatology service of a tertiary hospital. Tests were requested for differential and confirmatory diagnosis (whole genome sequencing). The Pharmacy Service collaborated in the search for a possible effective treatment and in adapting it to a paediatric patient.

Results Premature patient (41+2) hospitalised the 16 of August 2022 in a tertiary hospital due to respiratory distress and abnormal neurological signs, followed by a hypertonic seizure with generalised rigidity. A bolus of midazolam 0.1 mg/kg was administered without improvement, followed by phenobarbital 3 mg/kg/24h without clinical response. After negative tests, the genetic study detected an alteration of the GLRA1 gene in the patient, and a heterozygous mutation in the mother. A metabolic study was performed, detecting elevated levels of glutamic acid.¹ A therapeutic trial was started the 28 of August with oral Clonazepam at 0.1 mg/kg every 8 hours.¹ As this was a compounding preparation, the pharmacy prepared the suspension at a concentration of 0.1 mg/ml from 2 mg tablets.² Due to the improvement in stiffness and hypereplexia since the start of treatment, clonazepam was maintained at discharge, and continues being active at 0.3 mg/kg/8 hours. At follow-up at 11 months of age, the patient was in good general condition. The condition had attenuated, with less startle and reflexes.

Conclusion and Relevance Stiff syndrome is a disease that is difficult to diagnose and to treat due to its low prevalence. The favourable clinical response after starting treatment with clonazepam should be highlighted. The preparation of a pharmaceutical formulation from the Pharmacy Service allowed to individualise the dose according to the patient‘s weight and clinical evolution.

References and/or Acknowledgements 1. Sainia AG, Pandey S. Hyperekplexia and other startle syndromes. J Neurol Sci.2020,216:117051.

2. Polonini HC, Loures S, Lima LC, et al. Stability of Atenolol, Clonazepam, Dexamethasone, Diclofenac Sodium, Diltiazem, Enalapril Maleate, Ketoprofen, Lamotrigine, Penicillamine-D, and Thiamine in SyrSpend SF PH4 Oral Suspensions. Int J Pharm Compound. 2016;20:167–74.

Conflict of Interest No conflict of interest.