Sodium-glucose co-transporter type-2 inhibitors: pharmacology and peri-operative considerations.

Sodium-glucose co-transporter 2 (SGLT2) inhibitors are an emerging class of oral hypoglycaemic agents with therapeutic benefits beyond better glycaemic control. A major concern of the sodium-glucose co-transporter 2 inhibitors is their propensity to cause euglycaemic ketoacidosis in the peri-operative period and the potential for this critical diagnosis to be delayed or missed entirely. This review attempts to collate the case reports of sodium-glucose co-transporter 2 inhibitor ketoacidosis associated with surgery to highlight and put a perspective on this peri-operative issue. Preventive strategies and the management of the ketoacidosis are discussed.

Puffer fish poisoning: a potentially life-threatening condition.

Puffer fish poisoning has been documented rarely in Australia. It results from ingesting tetrodoxtoxin found in the liver, ovaries, intestines and skin of the fish. Over a recent 16-month period, 11 cases of puffer fish poisoning were reported to the NSW Poisons Information Centre. Symptoms of poisoning may include paralysis, respiratory failure, numbness, paraesthesia, nausea and ataxia. Health professionals should be aware of the condition so as to institute early and appropriate management.

Consensus neuropathological diagnosis of common dementia syndromes: testing and standardising the use of multiple diagnostic criteria.

The aim of this study was to assess the variation between neuropathologists in the diagnosis of common dementia syndromes when multiple published protocols are applied. Fourteen out of 18 Australian neuropathologists participated in diagnosing 20 cases (16 cases of dementia, 4 age-matched controls) using consensus diagnostic methods. Diagnostic criteria, clinical synopses and slides from multiple brain regions were sent to participants who were asked for case diagnoses. Diagnostic sensitivity, specificity, predictive value, accuracy and variability were determined using percentage agreement and kappa statistics. Using CERAD criteria, there was a high inter-rater agreement for cases with probable and definite Alzheimer's disease but low agreement for cases with possible Alzheimer's disease. Braak staging and the application of criteria for dementia with Lewy bodies also resulted in high inter-rater agreement. There was poor agreement for the diagnosis of frontotemporal dementia and for identifying small vessel disease. Participants rarely diagnosed more than one disease in any case. To improve efficiency when applying multiple diagnostic criteria, several simplifications were proposed and tested on 5 of the original 20 cases. Inter-rater reliability for the diagnosis of Alzheimer's disease and dementia with Lewy bodies significantly improved. Further development of simple and accurate methods to identify small vessel lesions and diagnose frontotemporal dementia is warranted.

Butterfly lesion of the corpus callosum due to Schilder's disease.

A 50 year old woman developed memory impairment and confusion over a 2 week period. CT scans of the brain showed a 'butterfly lesion' of the corpus callosum extending into the frontal lobes bilaterally. Stereotactic biopsy determined the lesion to be du e to demyelination. Further diagnostic investigations and the subsequent clinical course support the diagnosis of Schilder's disease.

Adult-onset exercise intolerance due to phosphorylase b kinase deficiency.

Muscle-specific phosphorylase b kinase deficiency is an unusual form of glycogen storage disorder. The majority of patients are male with an age at diagnosis between 15 to 36 years. Clinical features include exercise intolerance, myalgia and muscle weakness. A forearm ischaemic exercise test is usually normal and histochemical staining for myophosphorylase positive. The demonstration of reduced muscle phosphorylase b kinase activity by biochemical assay confirms the diagnosis. We report a 36 year old male with phosphorylase b kinase deficiency and symptom onset in adult life.

Bilateral optic disk pallor after unilateral internal carotid artery occlusion.

Bilateral pallor of the optic disks was observed in a 52-year-old man after dissection of an internal carotid artery. Diffuse pallor of the ipsilateral optic disk reflected infarction of the ipsilateral optic nerve and "bow-tie" atrophy of the contralateral optic disk reflected infarction of the ipsilateral optic tract. The findings were due to an occlusion of the internal carotid artery proximal to the origin of the ophthalmic artery, resulting also in insufficiency in the area of supply of the anterior choroidal artery.

Supranuclear disorders of eye movement.

Eye movements are the result of activity in discrete systems. Saccades and smooth pursuit movements respond to target position and target velocity respectively. Compensatory responses to movements that alter the position of the eyes in space depend upon the vestibular and optokinetic systems. Vergence movements allow fusion and binocular vision. Eye movement abnormalities of supranuclear origin may be divided into nystagmus, other ocular oscillations, saccadic dysfunction, smooth pursuit dysfunction, gaze palsy, tonic deviation, and vergence disability. An algorithm for the analysis of supranuclear eye movement disorders is presented.

Neuropathological findings in a case of chronic inflammatory polyneuropathy.

A 52-year-old woman presented with increasing pain, weakness, and paraesthesiae of four months' duration in the lower limbs. She suffered from chronic obstructive airways disease and hypertension. Neurological examination revealed wasting of the quadriceps muscles, weakness of the lower limbs, and absent ankle jerks. The sensory examination was normal. Full blood count, ESR, biochemical, immunological, and viral studies, urinary heavy metal assays, and cerebrospinal fluid examination were normal. Nerve conduction studies were consistent with a sensorimotor neuropathy, and electromyographic sampling was consistent with acute denervation. A sural nerve biopsy showed axonal degeneration and segmental demyelination. One month after admission, she developed carbon dioxide retention. Her weakness spread to affect the upper limbs, and she could not be resuscitated after a cardiac arrest three months after admission. General autopsy examination revealed bronchopneumonia. Neuropathological examination showed a lymphocytic infiltrate in the nerve roots of the cauda equina, the lumbosacral plexus, and the sural and vagal nerves. Increased cellularity and collagen were evident in these nerves. A diagnosis of chronic inflammatory polyneuropathy was made. The neuropathology of this entity is discussed.

Intermittent claudication of one cerebral hemisphere.

A 13-year-old girl consistently developed unilateral sensory and motor symptoms on hyperventilation, suggesting the diagnosis of hysteria. Investigation disclosed hypoplasia of one internal carotid artery and part of the circle of Willis, responsible for compromising blood flow to one hemisphere sufficiently to produce ischemic deficit during hypocapnia.

Neuropathological findings in a case of coexistent progressive supranuclear palsy and Alzheimer's disease.

A 66-year-old man was investigated for increasing forgetfulness and frequent falls. Following appropriate investigations, the cause was presumed to be senile dementia of the Alzheimer type. He was reviewed one year later and found to have impaired vertical gaze and a hoarse voice. Progressive dementia, nuchal rigidity, anarthria, and sphincteric incontinence developed subsequently. A diagnosis of progressive supranuclear palsy was made. He died four years after the initial assessment. Neuropathological examination revealed changes characteristic of progressive supranuclear palsy, and suggestive of Alzheimer's disease. Globose tangles, granulovacuolar bodies and gliosis were present in the midbrain, the pons, the dentate nucleus of the cerebellum, and the globus pallidus. Senile plaques and occasional neurofibrillary tangles and granulovacuolar bodies were found in the hippocampus, amygdala, and temporal cortex. The coexistence of two disease processes resulting in dementia is discussed.

Phoria adaptation to prisms. A cerebellar-dependent response.

Horizontal prism placement in normal subjects results in an apparent change in phoria by an amount equal in power and opposite in direction to the prisms used. However, the measured phoria gradually returns toward the value preceding the placement of prisms. This is termed phoria adaptation. This response was measured in five normal subjects and five patients with cerebellar deficit. The magnitude of the response was significantly reduced in the patient group. Visual acuities and fusional reserves were comparable in the two groups. The mean age was greater, and the stereoscopic acuity decreased, in the patient group. These factors were unlikely to account for the reduced response in patients. The results suggest that the phoria adaptation response in normal subjects depend on the integrity of the cerebellum.

A physiological approach to motor disorders.

Spasticity in man is presented as a disinhibition of spinal cord mechanisms, the responses to stretch depending on the interaction of the reflex effects of group Ia with those of group II afferent fibres. The reflex responses to muscle stretch and shortening in Parkinson's disease do not depend on an abnormality of spinal reflex mechanisms. The superimposition of physiological tremor or alternating tremor in rigidity produces the classical cog-wheel sensation. The phase lead of the action tonic stretch reflex was found to be reduced in patients with athetosis and cerebellar disease, thus diminishing damping of unwanted movements. The more complex transmission characteristics of the action tonic stretch reflex of normal man are absent in patients with spasticity and cerebellar lesions, presumably due to interference with long-loop pathways. In normal subjects gain of the reflex loop increases with voluntary contraction but in spasticity gain remains high irrespective of contraction level.