\documentclass[10pt]{article}

\usepackage{fullpage}
\usepackage{setspace}
\usepackage{parskip}
\usepackage{titlesec}
\usepackage[section]{placeins}
\usepackage{xcolor}
\usepackage{breakcites}
\usepackage{lineno}
\usepackage{hyphenat}





\PassOptionsToPackage{hyphens}{url}
\usepackage[colorlinks = true,
            linkcolor = blue,
            urlcolor  = blue,
            citecolor = blue,
            anchorcolor = blue]{hyperref}
\usepackage{etoolbox}
\makeatletter
\patchcmd\@combinedblfloats{\box\@outputbox}{\unvbox\@outputbox}{}{%
  \errmessage{\noexpand\@combinedblfloats could not be patched}%
}%
\makeatother


\usepackage{natbib}




\renewenvironment{abstract}
  {{\bfseries\noindent{\abstractname}\par\nobreak}\footnotesize}
  {\bigskip}

\titlespacing{\section}{0pt}{*3}{*1}
\titlespacing{\subsection}{0pt}{*2}{*0.5}
\titlespacing{\subsubsection}{0pt}{*1.5}{0pt}


\usepackage{authblk}


\usepackage{graphicx}
\usepackage[space]{grffile}
\usepackage{latexsym}
\usepackage{textcomp}
\usepackage{longtable}
\usepackage{tabulary}
\usepackage{booktabs,array,multirow}
\usepackage{amsfonts,amsmath,amssymb}
\providecommand\citet{\cite}
\providecommand\citep{\cite}
\providecommand\citealt{\cite}
% You can conditionalize code for latexml or normal latex using this.
\newif\iflatexml\latexmlfalse
\providecommand{\tightlist}{\setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}%

\AtBeginDocument{\DeclareGraphicsExtensions{.pdf,.PDF,.eps,.EPS,.png,.PNG,.tif,.TIF,.jpg,.JPG,.jpeg,.JPEG}}

\usepackage[utf8]{inputenc}
\usepackage[english]{babel}



\usepackage{float}








\begin{document}

\title{A Rare Incidence of Hypoxic-ischemic Encephalopathy Due to
Benzodiazepine Poisoning : A Case Report}



\author[1]{Uneeb Ullah Khan}%
\author[2]{Afshan Mumtaz}%
\author[3]{Muhammad Raheel Abdul Razzaque}%
\author[4]{Aabiya Arif}%
\author[3]{Sameer Tebha}%
\author[5]{Abubakr Yosufi}%
\affil[1]{Ziauddin University}%
\affil[2]{Karachi Medical and Dental College}%
\affil[3]{Jinnah Medical and Dental College}%
\affil[4]{Ziauddin Medical University}%
\affil[5]{Kabul University of Medical Sciences Abu Ali Ibn Sina}%


\vspace{-1em}



  
  \date{June 14, 2024}


\begingroup
\let\center\flushleft
\let\endcenter\endflushleft
\maketitle
\endgroup








\sloppy


\textbf{Introduction:~~}

Benzodiazepines are a class of sedative-hypnotic drugs often used by
people suffering from anxiety, sleep disorders, stress reactions, panic
disorders, obsessive-compulsive disorders, and mania due to their
anticonvulsant, anxiolytic, and muscle relaxant properties {[}1,2{]}.
Between the year 1996 to 2013, the percentage of US adults filling
benzodiazepine prescriptions rose from 8.1 million to 13.5 million (67\%
increase), and the cumulative quantity of benzodiazepines served over
the years surged by 140\% {[}3{]}. However, this rise in treatment using
benzodiazepines heavily contributed to an increase in the number of
cases of benzodiazepine overdose-related deaths, from 0.58 to 3.07 per
100,000 adults. This value soon reached a plateau in early 2010 but
continued to increase among the elderly and the Hispanic and African
American communities {[}3{]}. It is worth noting that nearly 75\% of
these deaths were not caused by benzodiazepines alone but by the added
effects of alcohol, opioids, or amphetamines {[}3{]}.

In mention to its relation with age, the use and misuse of
benzodiazepines vary, with individuals between the ages of 50 to 64
years having the highest prescription-based use, whereas young adults of
ages 18 to 25 years presented with the highest statistics for
non-prescription based use, highlighting the misuse and abuse of
benzodiazepines, according to a study conducted in the United States
{[}4{]}.

Overdoses induced by benzodiazepines rarely present as an emergency and
are often aggravated further by additional ingestion of other drugs
{[}5{]}. In people with long-term benzodiazepine use, immediate
retirement from the drug may induce a severe withdrawal syndrome,
resulting in anxiety, confusion, sleep disorders, and in extreme cases,
seizures {[}6{]}. The most widely used benzodiazepine, Alprazolam, has
much greater side effects from withdrawal, including mania, psychosis,
delirium, and hyperadrenergic states {[}7{]}. Furthermore, tapering of
benzodiazepines has been linked to Takotsubo cardiomyopathy {[}8{]}.

This article reports a case regarding a Pakistani patient with no
previous history of drug abuse that voluntarily overdosed on
benzodiazepines (Alprazolam) alone and was later diagnosed with
hypoxic-ischemic (anoxic) encephalopathy.

\textbf{Case Presentation:}

A 32-year-old Pakistani male was presented to the emergency department
in an unconscious and gasping condition. His mother had found him in an
unresponsive, comatose state. The patient had a history of epilepsy,
anxiety, and depression. The remainder of his past medical history was
unremarkable, and any admissions made during childhood had no recrudesce
in adulthood.

At the emergency department, the patient suffered multiple seizure
episodes, and remained unconscious, maintaining a GCS of 3/15. Upon
physical examination, unresponsive bilateral pinpoint pupils were noted;
the neck of the patient was found to be supple, and the bilateral
plantar reflexes were normal, suggesting active involuntary movement.
His abdomen was soft and nontender, and his chest was found to be
unremarkable.

On the first day of admission, a complete blood count revealed a low
hemoglobin count of 12.9 g/dl, leukocytosis (white blood cell count of
14.0 x 10\^{}9/L), neutrophilia (neutrophil at 93\%), hyperglycemia
(glucose concentration at 93 mg/dl) and hyperproteinemia (proteins: 66.1
mg/dl), while displaying a minor decrease in the hematocrit levels. The
test for plasma lactate levels was normal, resting at 15.5; however,
lactate dehydrogenase levels produced a low result of 21 U/L (the normal
range is 135 -- 225 U/L). The above-mentioned laboratory investigations
have been summarized in Table 1. Arterial blood gases revealed high
anion gap metabolic acidosis. On the second day of admission, a urine
test revealed a positive result for benzodiazepine overdose
(\textgreater{}200 ng/ml) while testing negative for amphetamines,
cannabinoids, barbiturates, and cocaine metabolites, as mentioned in
Table 2.~ Enzyme-linked immunosorbent assay for human immunodeficiency
virus (HIV) antibodies and tests for the presence of Hepatitis B and C
virus revealed negative results. The gram stain showed no organisms. On
the fifth day, a test for C-reactive protein (CRP) revealed a CRP of
15.62 mg/l (normal range is less than 6), suggesting the presence of an
inflammation reaction. His respiratory examination displayed acute
hypercapnic respiratory failure (type II).

A CT scan, which was also conducted on the first day, revealed no
intraparenchymal hemorrhage, cerebral edema, or midline shift. Grey and
white matter differentiation were intact, and the basal ganglia and
thalami showed normal density. This was viewed through multiple axial
images obtained from the base up to the vertex of the skull without
intravascular contrast.

Initial treatment for hypercapnic respiratory failure and seizures was
initiated, as these were the presenting symptoms when our patient had
arrived in the ER. He was intubated, aided by a pressure-synchronized
intermittent mandatory ventilation (P-SIMV) mode ventilator, and
transferred to the ICU for intensive care and monitoring. The patient
was administered anti-inflammatory glucocorticoids, intravenous lactam
antibiotics (meropenem, and tazobactam with piperacillin), levetiracetam
for the treatment of seizures, and half normal saline with 2 amps of KCL
at 75 ml/hr via a nasogastric tube as an immediate course of treatment.

On the third day, the patient had self-extubated but maintained an
oxygen saturation of 99\% and was supplied with 5 L/min oxygen via
facemask at a respiratory rate of 22/min. The patient's GCS topped
15/15, and reintubation was considered unnecessary. The patient was
drowsy, but was physically responsive and fully capable of conversing
with the consultant. On this day the patient was diagnosed with
benzodiazepine poisoning. The patient admitted to intentionally
overdosing on Alprazolam, a type of benzodiazepine, with suicidal
intentions, despite not having any history of using the drug or any
other illicit substances previously. He was later diagnosed with major
depressive disorder by the neurologist that overlooked the case.

Further in regards to the patient's condition, anion gaps returned to
normal, and no further seizures occurred. The patient remained fatigued,
but mobilization out of bed was prescribed. The patient had a
physiotherapy session in which chest physiotherapy was conducted. The
patient was kept in an ICU setting for another day before being
transferred to a normal monitoring setup.

In regards to the radiological tests taken following the initial CT
scan, an echocardiography, electroencephalography (EEG) and a general
abdomen ultrasound were taken on the third day. Echocardiography
revealed atypical septal motion and an ejection fraction of 55\%;
however, all other findings were normal, with an absence of thrombi or
pericardial effusions. EEG reported fast beta activity of 15-18 Hz in
the background rhythm and muscle stiffness due to ventilation; however,
photic stimulation was normal, and no focal or generalized epileptic
discharges were noted. Since idiopathic epilepsy appears normal on an
interictal EEG, the technician had advised that a diagnosis be made
after clinical correlation. The abdominal ultrasound showed a slightly
altered texture with raised echogenicity of the liver; however, the rest
of the abdomen was unremarkable. On the fifth and sixth days of
admission, a brain MRV/DWI and MRA were conducted to accurately view the
condition of the brain. MRA revealed a comparatively attenuated right
vertebral artery with normal hyperintensity within the right and left
vertebral, basilar, and bilateral posterior cerebral arteries. No
evidence of stenosis or abnormal dilation of the hyperintense arteries
was seen. The MRV presented evidence of bilateral symmetrical abnormal
signal intensity areas seen in the basal ganglia, predominantly in the
globus pallidus, which appears hyperintense on T2/FLAIR images while
showing restriction on the DWI images. The superior sagittal, inferior
sagittal, transverse, and straight sinuses appeared unremarkable, and no
venous segment filling was detected to show signs of thrombosis. Another
MRV, which was taken 24 hours after the first one, presented the Dural
sinuses as normal. The MRI, MRA, and MRV imaging, with DWI protocol,
demonstrates ischemic hypoxic insult involving bilateral globus
pallidus, which was later understood to be linked to the benzodiazepine
intoxication.

Upon gaining consciousness, the patient admitted to intentionally
overdosing on Alprazolam with suicidal intentions, despite not having
any history of using the drug or any other illicit substances
previously. He was later diagnosed with major depressive disorder by the
neurologist that overlooked the case.

On the final day, the patient possessed the following vitals: blood
pressure of 130/80, a pulse of 76/min, respiratory rate of 21/min, and
oxygen saturation of 99\% in the absence of oxygen support. The abdomen,
respiratory and cardiovascular examinations were completely normal. The
patient had fully gained consciousness, was well-oriented in time,
place, and person, and held a GCS of 15/15, with an attenuated right
vertebral artery under CNS findings. He was discharged after staying at
the hospital for 6 days and was instructed to return for a follow-up
after 1 week.

During the follow-up, the patient presented with no cognitive
deterioration and was completely responsive and healthy. The patient
presented with no personality changes and sustained a GCS of 15/15.

\textbf{Table 1}\selectlanguage{english}
\begin{longtable}[]{@{}llllll@{}}
\toprule
\textbf{Summary of complete blood picture (CP)} & \textbf{Summary of
complete blood picture (CP)} & \textbf{Summary of complete blood picture
(CP)} & \textbf{Summary of complete blood picture (CP)} &
\textbf{Summary of complete blood picture (CP)} & \textbf{Summary of
complete blood picture (CP)}\tabularnewline
\textbf{Investigations} & \textbf{Day 3} & \textbf{Day 4} & \textbf{Day
5} & \textbf{Day 6} & \textbf{Normal ranges}\tabularnewline
Hemoglobin (g/dl) & 12.9 & 11.9 & 11.9 & 12.8 & 13.7 -
16.3\tabularnewline
Red blood cell count (10\^{}12/L) & 4.08 & 3.77 & 3.76 & 4.04 & 4.5 -
6.5\tabularnewline
White blood cell count (10\^{}9/L) & 14 & 11.1 & 9.28 & 8.4 & 4.00 -
11.00\tabularnewline
Neutrophils (\%) & 93 & 92 & 76 & 76 & 40 -- 75\tabularnewline
Lymphocytes (\%) & 4 & 5 & 18 & 20 & 20 -- 45\tabularnewline
Platelet count (10\^{}9/L) & 195 & 188 & 190 & 158 & 150 --
450\tabularnewline
Urea (mg/dl) & - & - & - & 22 & 10.0 - 50.0\tabularnewline
Creatinine (mg/dl) & - & - & - & 0.89 & 0.9 - 1.3\tabularnewline
Sodium (mmol/L) & - & - & - & 145 & 136 -- 145\tabularnewline
Potassium (mmol/L) & - & - & - & 3.4 & 3.5 - 5.1\tabularnewline
Chloride (mmol/L) & - & - & - & 102 & 98 -- 107\tabularnewline
Bicarbonate (mmol/L) & - & - & - & 30 & 25 -- 29\tabularnewline
TSH (ulU/ml) & - & - & 0.854 & - & 0.4 - 4.2\tabularnewline
C reactive proteins (mg/l) & - & - & 15.62 & - &
\textless{}06\tabularnewline
Plasma lactate & 15.5 & - & - & - & 4.5 - 19.8\tabularnewline
\textbf{Cerebrospinal fluid (CSF) analysis} & \textbf{Cerebrospinal
fluid (CSF) analysis} & \textbf{Cerebrospinal fluid (CSF) analysis} &
\textbf{Cerebrospinal fluid (CSF) analysis} & \textbf{Cerebrospinal
fluid (CSF) analysis} & \textbf{Cerebrospinal fluid (CSF)
analysis}\tabularnewline
pH & - & 7 & - & - & 7.35 - 7.45\tabularnewline
Protein (mg/dl) & - & 66.1 & - & - & \textless{}45\tabularnewline
Glucose (mg/dl) & - & 90 & - & - & 30 -- 35\tabularnewline
LDH (U/L) & - & 21 & - & - & 135 -- 225\tabularnewline
LDH - Lactate Dehydrogenase & LDH - Lactate Dehydrogenase & LDH -
Lactate Dehydrogenase & LDH - Lactate Dehydrogenase & LDH - Lactate
Dehydrogenase & LDH - Lactate Dehydrogenase\tabularnewline
TSH - Thyroid stimulating hormone & TSH - Thyroid stimulating hormone &
TSH - Thyroid stimulating hormone & TSH - Thyroid stimulating hormone &
TSH - Thyroid stimulating hormone & TSH - Thyroid stimulating
hormone\tabularnewline
\bottomrule
\end{longtable}\selectlanguage{english}
\begin{longtable}[]{@{}ll@{}}
\toprule
\textbf{Table 2} &\tabularnewline
\midrule
\endhead
\textbf{Summary of urine test} &\tabularnewline
\textbf{Investigations} & \textbf{Results}\tabularnewline
Amphetamine & Negative\tabularnewline
Urinary cannabinoids & Negative\tabularnewline
Urinary barbiturates & Negative\tabularnewline
Urinary benzodiazepines* & Positive\tabularnewline
Urinary opiates & Negative\tabularnewline
Urinary cocaine metabolites & Negative\tabularnewline
\textbf{(*) test was rechecked} &\tabularnewline
\bottomrule
\end{longtable}

\textbf{Discussion:~}

The syndrome of hypoxic-ischemic encephalopathy (HIE), also referred to
as anoxic encephalopathy, is often caused by brain injury due to
asphyxia; it can be divided into acute and subacute classes. The patient
discussed in this report was admitted due to an acute case of
intentional benzodiazepine poisoning, presenting in a comatose state
with type II acute respiratory failure, hypotension, metabolic acidosis,
seizures, and developed hypoxic-ischemic encephalopathy (HIE) secondary
to benzodiazepine poisoning. In most cases, HIE is seen in adults who
are patients of cardiac arrest.

Common symptoms of benzodiazepine overdose include ataxia and
unresponsiveness, and a physical examination often reveals nystagmus,
respiratory depression, hypotension, and coma. These symptoms are seen
as a result of central nervous system (CNS) depression due to the
agonist action of benzodiazepines on GABA-A receptors, causing an influx
of chloride ions into the neuron and facilitating hyperpolarization.

Due to the hypercapnic state of the patient, possessing a PaCO2 of more
than 50 mmHg, acute respiratory failure was established and is followed
by hypoxemia if air at atmospheric pressure is breathed in. Hence
patients often require intubation and ventilation. Due to the necessity
for intubation and ventilation, the patient was supplied with oxygen via
a P-SIMV mode ventilator, which aided in maintaining a set number of
breaths, allowing for the reversal of hypercapnia and restoring PaCO2
and pH levels to normal.

MRI findings in our case presented abnormal bilateral signal intensity
areas, particularly in the globus pallidus of the basal ganglia, and
attenuated cerebral blood flow in the right vertebral artery. No other
forms of damage were noted. Such findings align with MRI assessments of
previous adult hypoxic-ischemic brain injury cases. As stated in the
literature, increased signal intensities in the basal ganglia,
cerebellar hemispheres, or the peri Rolandic and occipital cortices of
the cerebral cortex are seen in DWI taken in the initial 24 hours of the
injury {[}9{]}. Certain studies have also mentioned that regions of the
thalami, hippocampi, or brain stem may also be involved {[}9,10,11{]}.
The reason why such specific regions of the brain are involved in the
damage is because hypoxic-ischemic injury particularly attacks the
sensitive grey matter of the brain, which is abundant in the cerebral
cortex, cerebellum, basal ganglia, thalami, and hippocampi {[}9,12{]}.
Due to the abundance of glutamate receptors on the post-synaptic
dendrites, these regions are particularly susceptible to glutamate
excitotoxicity, providing an explanation for the pathophysiology behind
grey matter injury. When placed concerning age groups, cerebellar damage
is seen more commonly among the elderly, despite its presence in
neonates as well. This is due to the presence of immature Purkinje
cells, which protect the neurons of the cerebellar cortex from ischemic
damage {[}13{]}.

CT findings of hypoxic-ischemic brain injury seen in adults generally
present with edema formation in spaces containing cerebrospinal fluid,
decreased attenuation of the cortical grey matter, and reduced to
complete loss of the grey-to-white matter differentiation {[}12{]}. None
of these findings were seen in our patient. This may be due to the
underlying fact that our patient is, firstly, of a younger age group
than patients that showed such symptoms, and secondly, the extent of the
injury was relatively mild. Adults who suffer a severe hypoxic injury
often display symptoms of reversal sign and white cerebellum sign
{[}11{]}. The reversal sign presents with hypoattenuation of white
matter and diffuse cortical swelling. In contrast, the white cerebellum
sign presents with elevated attenuation of the brain stem and cerebellum
compared to that of the cerebral cortex due to the posterior shunting of
blood following anoxia; the prognosis for both, the reversal sign and
the white cerebellum sign are poor {[}14{]}. Our patient presented with
neither of these findings on his CT scan, suggesting that his level of
injury was far from severe.

It is well understood that the main treatment method for benzodiazepine
poisoning is supportive care and management, which is necessary as
mortality second to sedative-hypnotic overdose is commonly seen due to
cardiorespiratory arrest. For effective systemic maintenance,
immunoassay screening is paramount, along with the test for arterial
blood gas (ABG), electrocardiogram (ECG), blood glucose level
(especially if the patient is in an altered state of mind), serum
electrolytes, ethanol concentrations, and acetaminophen levels. Upon
conducting a urine analysis, the patient presented positive for
benzodiazepines alone, with an absence of acetaminophen and ethanol. As
previously stated, benzodiazepines do not present fatal symptoms on
their own, however in the case of our patient, HIE secondary to
poisoning was diagnosed, revealing a new understanding of the various
toxic presentations of benzodiazepine overdose.

The patient was also tested for HIV antibodies and the presence of HBV
and HCV, which all revealed negative results. Along with being used as
an anticonvulsant, benzodiazepines are commonly abused and used for
recreational purposes. Patients brought in with benzodiazepine overdose
are screened for HIV and HCV to verify if the patient presents
'risk-taking behaviors' and often indulges in the misuse of drugs,
unsafe injection usage, and unprotected sexual behaviors {[}16,17{]}.
According to a study conducted in 2015,~ Because the mentioned patient
presented a negative result for the HIV antibodies, and HBV and HCV
tests, it can be assumed that the patient is not a frequent drug user,
and even if so, does not part-take in acts of misuse or drug abuse.

Further highlighting the aspect of treatment, single-dose activated
charcoal, and orogastric lavage are known treatment options when
considering benzodiazepine poisoning; however, these methods are greatly
discouraged and not considered as first-line treatment as the extent of
risk outweighs their benefits. Additionally, flumazenil is an
FDA-approved benzodiazepine antagonist which is used to reverse the
sedative action of benzodiazepines under conscious sedation and general
anesthesia {[}18,19{]}. It acts by competitively inhibiting the binding
of benzodiazepines to the benzodiazepine receptor on the GABA receptor
complex, and it is known to reverse the effects of sedation, antagonize
memory loss, and recover psychomotor activity. However, there are great
contraindications and adverse effects linked to flumazenil, including
hypertension, bradycardia, nausea, hypersensitivity reactions, hearing
loss, panic attacks, psychotic disorders, diaphoresis, seizures, and
arrhythmias {[}20{]}. Furthermore, the patient requires extensive
monitoring after administration in case of respiratory depression,
benzodiazepine withdrawal, and other residual effects, especially for
the first 2 hours {[}21{]}. Due to this reason, flumazenil is not
commonly used to treat benzodiazepine overdose. Due to self-extubation
and the various adverse effects listed above, the patient mentioned in
this report was not given flumazenil. His poisoning was entirely treated
by monitoring and managing ABGs, electrolytes, and seizures until the
patient recovered.

\textbf{Pathophysiology of hypoxic-ischemic encephalopathy (HIE)}

The syndrome of hypoxic-ischemic encephalopathy (HIE), also referred to
as anoxic encephalopathy, is often caused by brain injury due to
asphyxia; it can be divided into acute and subacute classes. HIE can be
caused by various conditions or insults, including cardiac arrest,
hypoxic arrest, and carbon monoxide (CO) poisoning. In this section, the
pathophysiology of HIE due to a purely hypoxic event will be discussed,
and how it applies to the patient involved in this report.

Due to its rapid decline in activity and response as a result of poor
oxygen supply, metabolic instabilities, and energy indigence, the brain
parenchyma is seen as vulnerable to any sort of injury or insult. It
begins with the blockage of blood flow to the brain parenchyma via the
cerebral arteries, which is generally a result of poisoning (drug
overdose or carbon monoxide poisoning), vascular injury, and in certain
cases, cardiac arrest {[}22{]}.

Generally, encephalopathy is often reworded as HIE following an event of
resuscitation. However, HIE can be further divided into brain injury
following cardiac arrest, brain injury due to hypoxic arrest, and brain
injury following carbon monoxide intoxication; each subsets'
pathogenesis and etiology are relatively different. Furthermore, the
extent of hypoxia is determined by the duration and type of
insult/injury; cardiac arrest is a common cause of global hypoxia,
whereas vascular injury commonly presents a localized extent to the
hypoxia {[}23{]}.

In the case of a purely hypoxic event, severe brain damage is rare,
especially when global circulation is maintained, but the difference in
neuronal function and microscopic damage is commonly seen. It is due to
this reason that patients presented in the emergency department
following a pure hypoxic event are unresponsive or in a comatose state.
Obstruction of the airway and intoxication/overdose (due to drugs or
toxins) are common causes of a purely hypoxic syndrome. Partial
pressures of carbon dioxide in the blood increase, decreasing the pH as
a consequence of hypoxia, inducing acidosis. Vasodilation is seen due to
cerebral homeostatic autoregulation, increasing the flow of blood to
continually supply the neurons with glucose and other nutrients while
removing the toxin or drug and their metabolites from the surrounding
tissue fluid. In addition, astrocytic swelling of glial cells due to
increased acidosis and hypercapnia is also a common phenomenon that
leads to brain edema {[}24{]}. A hypoxic attack generally acts on the
synapse of neurons, creating a deficit of GABA molecules, due to which
seizures and myoclonus often follow.

Global brain ischemia is also commonly seen due to the shift from
aerobic to anaerobic respiration, leading to the fall of ATP levels in
the cerebral blood and an accumulation of lactic acid. This leads to
membrane damage. Furthermore, an influx of calcium ions into the
postsynaptic neurons leads to further membrane damage, activation of
various cytotoxic processes, and triggering the membrane phospholipase,
producing oxygen free radicals. Mitochondrial membrane damage may
insure, causing the leakage of cytochrome enzymes. The extent of ATP
depletion is a contributing factor to the death of the cell; if the
depletion is grand, the cell often dies via necrosis; however, if the
neurons survive the initial hypoxic insult and the extent of energy
depletion is far less, apoptosis ensues after a certain period.

Another syndrome under HIE is delayed post-hypoxic leukoencephalopathy;
an uncommon condition that develops in patients exposed to hypoxia for a
considerable period, inciting severe damage to the brain cortical and
deep white matter {[}25,26{]}. When presented, patients are generally
comatose but soon recover and reestablish neuronal function and maintain
normal cognitive behavior, however these later decline, following a
period of approximately 10 days, after which the patient shows poor
motor function and a sudden change in personality (agitated, confused
and easily irritable). Tests reveal extensive demyelination of neurons
within the white matter while maintaining sufficient cerebral blood
flow, leading to leukoencephalopathy. Edema formation during
demyelination is uncommon as it subsides naturally 2 to 4 days following
the initial hypoxic insult {[}25{]}. The true pathogenesis of
demyelination is not yet understood and requires further attention. In
the case of our patient, no personality or cognitive changes were noted
upon follow-up, suggesting that the patient did not suffer from
post-anoxic leukoencephalopathy following the initial hypoxic insult.

\textbf{Mechanism of action of benzodiazepines}

The mechanism of action of benzodiazepines and the extent of their
effects have been well studied. Benzodiazepines belong to a class of
drugs that act agonistically on the gamma-aminobutyric acid (GABA)
receptors, specifically the GABA-A receptors, by acting on the
benzodiazepine receptors, which are formed by the extracellular portions
of the alpha and gamma subunits of the GABA-A receptors.

Benzodiazepines are known agonists of the gamma-aminobutyric acid (GABA)
receptors, specifically the GABA-A receptors. They bind to the
benzodiazepine binding sites formed by the alpha and gamma subunits of
the GABA-A receptors (ligand-gated ion channels), causing a
conformational change in the central pore structure of the GABA-A
receptors, channeling an influx of chloride ions in the neuron,
resulting in hyperpolarization of the neuron and generalized depression
of the central nervous system (CNS) {[}27{]}. An inhibitory effect is
seen due to a decrease in the resting potential of the neuron because of
the increased inclusion of a negative charge. It is worth noting that
benzodiazepines are nearly non-functional in the absence of GABA
molecules and require the presence of GABA on the GABA-A receptors to
initiate the increased influx of chloride ions {[}28{]}.

Decreased concentrations of GABA between neurons results in an increased
occurrence of psychiatric conditions such as anxiety, schizophrenia,
autism spectrum disorder, and major depressive disorder. At a level of
clinical significance, GABA-A receptor agonists are not considered to be
the first line of treatment for psychiatric disorders linked to GABA
suppression due to their addictive properties and major consequences of
overdose (intentional or accidental) {[}29,30{]}.

A study conducted by Schur et al. investigated the relation between
known patients of psychiatric illnesses and altered brain GABA levels
measured using proton magnetic resonance spectroscopy (1H-MRS) across 40
(N=1,591), involving cases of bipolar disorder, major depressive
disorder, schizophrenia, autism spectrum disorder, panic disorder,
posttraumatic stress syndrome, and attention-deficit/hyperactivity
disorder. It was concluded that patients with autism spectrum disorder
and major depressive disorder were the only groups to show visible
depression in brain GABA levels. Patients with autism spectrum disorder
(p-value: 0.001) and major depressive disorder who are actively
depressed (p-value: 0.005) were statistically significant and showed
lower brain GABA levels when compared to healthy controls, whereas
remitted patients of major depressive disorder showed no significance
(p-value: 0.310) {[}30{]}.

\textbf{The link to Suicide}

The relation between psychiatric illnesses and decreased levels of brain
GABA is an underlying cause for the prevalent usage of benzodiazepines
as a mode of treatment; however, due to their sedative nature and ease
in accessibility, the use of benzodiazepines is often abused for
self-pleasure leading to addiction or suicide. The patient mentioned in
this article stated that he had intentionally overdosed on
benzodiazepines Alprazolam due to unemployment and familial pressures.

Statistics regarding the total number of deaths due to suicide,
particularly suicide by poisoning, are unreliable because Pakistan, a
developing Muslim country, is scarce and neither compiles such reports
nor publishes them annually {[}31{]}. Approximately 19,331 deaths were
estimated by the WHO in 2019, with acts of self-harm possessing an
elevation of approximately 10 to 20 times the estimated number of deaths
{[}32{]}. Furthermore, the act of suicide or any other form of self-harm
is disparaged and denounced religiously and considered illegal in the
country, such that survivors can be prosecuted in a court of law. In
Pakistan, all suspected cases of suicide or parasuicide are titled
''medicolegal'' and must be investigated by medicolegal officers (MLOs)
that are stationed at medicolegal centers (MLCs) within all
government-funded hospitals. In contrast, privately funded hospitals are
given leverage as to whether they wish to report such cases, providing a
reason why most cases of attempted suicide are predominantly found in
privately funded hospitals.

A study conducted by Khan et al. investigated the use of
benzodiazepines, such as diazepam, among attempted suicide cases over
the course of 5 years. Results showed that from the total of 447
patients, 73\% of the cases were through the overdose of
over-the-counter medication. Of the total 274 patients who overdosed on
benzodiazepines (69\% used diazepam), 91\% overdosed on benzodiazepines
alone, whereas only 9\% used it in concomitance with other drugs or
physical methods. 80\% of patients that overdosed on benzodiazepines
showed no signs of complication and were discharged within 3 days. None
of these cases led to mortality {[}33{]}. This further verifies that
overdose on benzodiazepines alone is rarely fatal, and most studies show
that if mortality has been exhibited, it is due to the overdose of
benzodiazepines in concurrence with other drugs such as opioids,
alcohol, and amphetamines.

\textbf{Conclusion:}

The symptoms and adverse effects regarding benzodiazepine poisoning
alone are poorly understood and require further investigation as to what
symptoms present upon immediate action of the drug and the progression
of symptoms over the course of time. Furthermore, it is worth
investigating the extent of acute benzodiazepine overdose-induced anoxia
on the various sections of the brain, particularly the gray matter, and
the extent of behavioral deterioration seen over a period following the
initial hypoxic injury.

\textbf{Acknowledgments}

None

\textbf{Data Availability Statement}

Not applicable

\textbf{Ethics Statement}

Informed consent was acquired from the patient and/or guardian for the
publication of this case report and all relevant images.

\textbf{Funding Statement}

No funding was acquired

\textbf{Conflict of Interest Statement~~}

Authors declare no conflicts of interest

\textbf{References:~}

\begin{enumerate}
\tightlist
\item
  Prescription and non-prescription sleep product use among older adults
  in the United States
\item
  Prevalence and correlated of benzodiazepine use, misuse and use
  disorders among adults in the United States
\item
  Increasing Benzodiazepine Prescriptions and Overdose Mortality in the
  United States, 1996--2013
\item
  Benzodiazepine use and misuse among adults in the United States
\item
  A Retrospective Review of Morbidity and Mortality Associated with
  Acute Benzodiazepine Withdrawal at a Midwestern Academic Medical
  Center
\item
  Treatment for benzodiazepine dependance
\item
  A review of alprazolam, use, misuse and withdrawal
\item
  Takotsubo cardiomyopathy secondary to benzodiazepine tapering: An
  underreported complication.
\item
  Diffusion weighted MR imaging of global cerebral anoxia.
\item
  Value of MR imaging of the brain in children with hypoxic coma
\item
  Hypoxic brain damage: cortical laminar necrosis and delayed changes in
  white matter at sequential MR imaging.
\item
  Early CT findings of global central nervous system hypoperfusion
\item
  Selective vulnerability and the cerebellum in neonate
\item
  The reversal sign
\item
  Benzodiazepines induce hyperglycemia in rats by affecting peripheral
  disposal of glucose
\item
  Sex differences in benzodiazepine use in the HIV-infected population
\item
  Prescription drug misuse and risk behaviors among young injection drug
  users
\item
  Pharmacological interventions for benzodiazepine discontinuation in
  chronic benzodiazepine users
\item
  Structure of a human synaptic GABAA receptor.
\item
  Adverse Events Associated with Flumazenil Treatment for the Management
  of Suspected Benzodiazepine Intoxication--A Systematic Review with
  Meta-Analyses of Randomised Trials.
\item
  A Pharmacokinetic-Pharmacodynamic Study of Intravenous Midazolam and
  Flumazenil in Adult New Zealand White-Californian Rabbit
\item
  Hypothermia after Cardiac Arrest Study Group. Mild therapeutic
  hypothermia to improve the neurologic outcome after cardiac arrest
\item
  Hyperthermia after cardiac arrest is associated with an unfavorable
  neurologic outcome.
\item
  The effect of acute hypoxia and hypercapnia on the ultrastructure of
  the central nervous system
\item
  Delayed neurological deterioration after anoxia
\item
  Hypoxic-ischemic leukoencephalopathy in man
\item
  Anxiolytics targeting GABAA receptors: Insights on etifoxine.
\item
  Structure, function, and modulation of GABA(A) receptors.
\item
  GABA, gamma-hydroxybutyric acid, and neurological disease
\item
  Brain GABA levels across psychiatric disorders: A systematic
  literature review and meta-analysis of (1) H-MRS studies.
\item
  Suicide and deliberate self-harm in Pakistan: a scoping review
\item
  World Health Organization. Suicide worldwide in 2019: global health
  estimates. Geneva World Health Organization; 2021
\item
  Benzodiazepine Self-Poisoning in Pakistan: Implications for Prevention
  and Harm Reduction
\end{enumerate}

\textbf{Hosted file}

\verb`Table-1.docx`  available at \url{https://authorea.com/users/677118/articles/674329-a-rare-incidence-of-hypoxic-ischemic-encephalopathy-due-to-benzodiazepine-poisoning-a-case-report}

\textbf{Hosted file}

\verb`Table-2.docx`  available at \url{https://authorea.com/users/677118/articles/674329-a-rare-incidence-of-hypoxic-ischemic-encephalopathy-due-to-benzodiazepine-poisoning-a-case-report}

\selectlanguage{english}
\FloatBarrier
\end{document}

